Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Executive Summary 2
and repetitive damage. This plan aligns with federal and state hazard mitigation planning regulations and requirements to ensure eligibility for pre- and post-disaster mitigation funding through the Federal Emergency Management Agency (FEMA) for all jurisdictions that participated as Planning Partners:
• City of Palos Verdes Estates
• City of Rancho Palos Verdes
• City of Rolling Hills
• City of Rolling Hills Estates
• Klondike Canyon Geologic Hazard
Abatement District
• Abalone Cove Landslide Abatement
District
BUILDING THE PLANNING TEAMS
The Palos Verdes Peninsula cities and special purpose districts brought together a diverse and inclusive group of individuals to participate, develop, and implement the MJHMP. A Core Planning Team, Planning Committee, and Planning Partnership oversaw the planning process and were responsible for coordinating, overseeing, and executing the planning process.
CORE PLANNING TEAM HAZARD MITIGATION
PLANNING COMMITTEE PLANNING PARTNERSHIP
The Core Planning Team was
made up of key personnel from the
cities and discipline leads from the
City of Rolling Hills Estate’s
contract consultant, Black &
Veatch.
The Planning Committee consisted
of a variety of personnel from
Palos Verdes Peninsula city
departments and agencies, local
jurisdictions, and stakeholders that
guided the cities and participating
jurisdictions through the process
of updating the MJHMP.
The Planning Partnership included
jurisdictional representatives
seeking DMA 2000 compliance.
They participated throughout the
process, reviewed information,
provided input, informed the risk
assessment, developed mitigation
strategies, and adopted the
MJHMP.
OUTREACH STRATEGY
The Core Planning Team (CPT) implemented a multimedia public involvement strategy that was approved by the Hazard Mitigation Planning Committee (HMPC). The strategy included a community hazard mitigation awareness survey; a project web page; and multiple in-person events promoting hazard awareness. Additionally, the HMPC helped amplify public outreach efforts to their networks.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Executive Summary 3
RISK ASSESSMENT
A risk assessment is the process of measuring the potential loss of life resulting from natural hazards, as well as personal injury, property damage, and environmental damage. The assessment determines a community’s overall vulnerability to hazard events. The HMPC used the risk assessment to gauge the potential impacts of natural hazards identified as “hazards of concern” for this plan.
Risk assessment models for hazards of concern were based on current data and technologies. The assessment of each hazard of concern includes discussion of the following:
• Hazard identification and profile.
• The exposure of population, property, and the environment to the hazards. • The estimated cost of potential damage, where applicable.
Based on the risk assessment, the hazards of concern were ranked for the risk they pose to the Planning Area. Palos Verde Peninsula-wide results are as follows:
In addition to assessing the hazards of concern, this plan provides a review of “hazards of interest.” The HMPC determined that these other hazards, though not required to be evaluated under federal guidelines for hazard mitigation plans, are important to recognize qualitatively in this plan. Hazard profiles, without quantitative risk assessments, are provided for the following hazards of interest:
• Groundwater Seepage
• Human-Caused
• Hazardous Materials
• Utility Related
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Executive Summary 2
CAPABILITY ASSESSMENT
A robust assessment of mitigation capabilities was completed by each participating jurisdiction to identify gaps that may need to be addressed so mitigation actions can be successfully implemented.
The following capability types were analyzed:
• Planning and Regulatory
• Development and Permitting
• Administrative and Technical
• National Flood Insurance Program
(NFIP) Compliance
• Public Outreach
• Fiscal
• Participation in Other Programs
• Adaptive Capacity
MITIGATION STRATEGY
The HMPC developed mitigation goals to reflect the current focus of Palos Verde Peninsula and its participating jurisdictions. The HMPC determined the following goals for this MJHMP:
• Goal 1. Reduce risk to life, property, community
lifelines, the environment, and infrastructure from
natural hazards and climate change.
• Goal 2. Expand and improve public awareness of
hazards, risk, and mitigation strategies.
• Goal 3. Strengthen partnerships and
communication among government agencies,
private sector businesses, community-based, and
nonprofit organizations.
• Goal 4. Integrate mitigation principles into
regulations, policies, programs, and guidance to
support equitable outcomes to benefit the whole
community.
• Goal 5. Conserve, enhance, rehabilitate, and
protect natural and cultural resources from
hazards to provide a more resilient and
sustainable community.
Mitigation actions presented in this plan are designed to reduce or eliminate losses resulting from natural hazard events. The development process resulted in the identification of nearly 200 mitigation actions for implementation by individual Planning Partners, as presented in the jurisdictional annexes in Volume 2 of this MJHMP. Several of these actions are within the current capabilities of each jurisdiction, resulting in a high priority for implementation over the next 5 years.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Executive Summary 5
IMPLEMENTING, ADOPTING, AND MAINTAINING THE PLAN
Implementing the mitigation actions in this MJHMP will take time and resources over its 5-year performance period. The CPT developed an implementation and maintenance strategy that includes the following:
• Monitoring mitigation action implementation.
• Progress reporting.
• A strategy for continued public involvement.
• Plan integration with other relevant plans and programs.
This MJHMP is designed with an adaptive management approach that can evolve along with funding sources and state and federal mandates. The Palos Verde Peninsula Planning Partners will assume responsibility for adopting the recommendations of this plan and committing resources toward implementation. The framework established by this plan will enable the Planning Partnership to pursue FEMA Hazard Mitigation Assistance (HMA) grant funding for feasible, eligible, cost-effective actions. The Planning Partnership developed this plan with extensive opportunities for public involvement and input.
Public support of the mitigation actions identified in this MJHMP will ensure its success.
Paddock in Rancho Palos Verdes (Photo Credit: Megan Brotherton) Part 1
Introduction and Planning
Process
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Introduction 1-1
1. INTRODUCTION
1.1 WHY PREPARE THIS PLAN?
Palos Verdes Peninsula Bluffs (Photo Credit: Adobe Stock) The Palos Verdes Peninsula cities and two special purpose districts, the Planning Partnership, prepared this MJHMP update to better protect the residents, property, and assets throughout the Palos Verdes Peninsula from the effects of natural hazards.
Hazard mitigation plays a crucial role in emergency management by working to reduce the impacts of disasters on individuals, communities, and important assets. By implementing mitigation measures, we can help prevent the same areas from being repeatedly impacted by disasters. Mitigation is part of the emergency management cycle, which is divided into the following four phases:
• Preparedness is when we develop or update activities, programs, and systems before an event happens. These activities are often tested (or exercised) in non-emergency situations. This tests their effectiveness. Emergency managers also assess potential risks, hazards, and vulnerabilities in this phase.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Introduction 1-2
• Response focuses on the immediate and short-term effects of a disaster. It is usually focused on life safety and preventing immediate damage.
• Recovery is a long-term phase that
looks to return a community to normal,
or to a more resilient state, after a
disaster.
• Mitigation focuses on building (or
rebuilding) in ways that reduce the risk
more permanently. It is an activity that
can occur at any point in the emergency
management cycle. For example,
communities can undertake mitigation
actions before a disaster (the
preparedness phase) or while
rebuilding after a disaster (the recovery
phase) (FEMA, 2023).
This multi-jurisdictional hazard mitigation plan (MJHMP) update highlights the dedication of the Palos Verdes Peninsula Planning Partnership to reducing risk from hazards, enhancing overall resilience, and providing a practical tool for decision makers to incorporate mitigation into daily operations.
1.1.1 Federal Eligibility
Disaster Mitigation Act
In an effort to reduce the nation's mounting natural disaster losses, the U.S. Congress passed the Disaster Mitigation Act of 2000 (DMA 2000), which amended the Robert T.
Stafford Disaster Relief and Emergency Assistance Act.
Section 322 of DMA 2000 emphasizes the need for state
and local government entities to closely coordinate on
mitigation planning activities and requires an HMP for any local government applying for federal mitigation grant
funds. These funds primary fall under the Federal
Emergency Management Agency (FEMA) Hazard Mitigation
Assistance (HMA) program. Grant programs under HMA
include the following:
• Flood Mitigation Assistance
• Hazard Mitigation Grant Program (HMGP)
Entities with an adopted and federally-approved HMP are pre-positioned to receive available mitigation funds before and after the next disaster strikes. The plan was developed to make the Planning Partnership eligible for pre- and post-disaster FEMA grants.
Hazard mitigation is any sustained
action taken to reduce or eliminate
long-term risk to life and property from
hazards.
FEMA defines a Hazard Mitigation
Plan as a community-driven process
to help state, local, tribal, and territorial
governments plan for hazard risk. By
planning for risk and setting a strategy
for action, governments can reduce
the negative impacts of future
disasters.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Introduction 1-3
1.1.2 Purposes for Planning
This MJHMP update highlights the Palos Verdes Peninsula Planning Partnership's dedication to reducing risk from hazards, enhancing overall resilience, and providing a practical tool for decision makers to incorporate mitigation into daily operations. The Planning Partnership prepared this DMA-compliant MJHMP to identify resources, information, and strategies for reducing risk from natural hazards.
Elements and strategies in the plan were selected because they meet a program requirement and the intent of the Palos Verdes Peninsula and its residents to mitigate hazards. The plan will help guide mitigation activities throughout the Planning Area. It was developed to meet the following needs:
• Meet or exceed program requirements specified under DMA; • Enable the Palos Verdes Peninsula Planning Partnership to apply for federal grant funding to reduce hazard risk through mitigation;
• Fulfill state and federal requirements for hazard mitigation planning; • Create a risk assessment that focuses on the hazards of concern in the Palos Verdes Peninsula Planning Partnership’s Planning Area; and
• Coordinate existing plans and programs so high-priority projects to mitigate potential disaster impacts are funded and implemented.
An HMP is a living document that jurisdictions use to reduce vulnerability to natural hazards. It serves as the groundwork for a jurisdiction’s long-term plan to lessen disaster impacts and establishes a framework for decision-making to mitigate harm to individuals, assets, and the economy from future natural disasters. Mitigation projects include a broad range of actions to help reduce vulnerability, allowing Palos Verdes Peninsula to bounce back more quickly from disasters. This ongoing effort ensures that the Palos Verdes Peninsula Planning Partnership has the necessary information to create and implement a successful mitigation strategy, reduce the impacts of natural disasters, and enhance overall resilience.
1.2 PLAN UPDATES
1.2.1 Previous Plans
The Palos Verdes Peninsula cities have shown dedication to reducing disaster impacts by adopting the following local hazard mitigation plans:
• City of Palos Verdes Estates Local Hazard Mitigation Plan, 2018 • City of Rolling Hills Hazard Mitigation Plan, 2019
• Rancho Palos Verdes and Rolling Hills Estates Multi-Jurisdictional Hazard Mitigation Plan, 2020
1.2.2 Why Update
The prior plans needed to be updated for funding eligibility and to encompass a diverse Planning Partnership that included a unified plan for all the cities on the Peninsula and two special purpose districts. Throughout the planning process, the plan was developed with a focus on assessing changes in vulnerability caused by hazard events, evaluating capabilities and their utilization in implementing hazard mitigation measures, reviewing the prior mitigation strategies, and identifying new initiatives to enhance overall resilience across the Planning Area.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Introduction 1-4
Federal and State Requirements
In response to the requirements of the DMA 2000, which requires local governmental agencies to develop and update its hazard mitigation plan every 5 years, this plan serves as the 2026 update to the prior Local Hazard Mitigation Plans developed by the Planning Partners. The Palos Verdes Peninsula MJHMP update is in alignment with FEMA’s Local Mitigation Planning Policy Guide (April 2025), FEMA’s Local Mitigation Planning Handbook (June 2025), and the State of California planning requirements.
Changes in Hazards
The 2026 Palos Verdes Peninsula MJHMP update includes the previously identified hazards in the respective plans developed by the Planning Partners, along with one additional hazard of concern (italicized), as follows:
• Drought
• Earthquake
• Flood
• Heat Wave
• Landslide
• Strong Wind
• Wildfire
Changes in Development and Population
Local Plan Requirement E1—44 CFR Part 201.6(d)(3)
A local jurisdiction must review and revise its plan to reflect changes in development.
Tracking previous and future growth in potential hazard areas provides an overview of increased exposure to hazards within a community. This requirement ensures that the mitigation strategy continues to address the risk and vulnerability of existing and potential development and takes into consideration possible future conditions that could impact vulnerability.
As of January 2025, the reported population for the Planning Area was 63,948, representing a slight decrease of 2.3 percent from the 2020 reported population (California Department of Finance, 2025).
Based on development permit data provided by the municipal Planning Partners (refer to Volume 2), permits were issued for the construction of new structures over the past 5 years.
This plan assumes that some of this new development occurred in hazard areas. All such new development would have been regulated pursuant to local programs and codes, such as the International Building Code and flood damage prevention requirements of the National Flood Insurance Program (NFIP). Therefore, it is assumed that hazard vulnerability did not measurably increase, even if exposure did. Palos Verdes Peninsula municipalities have general plans that govern land-use decisions and policymaking, as well as building codes and flood-management regulations based on state and federal mandates.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Introduction 1-5
1.2.3 The Updated Plan - What Has Changed?
The overall planning process and the 2012 HMP have been improved and revised for this 2025 MJHMP in response to changes in planning requirements and overall improvements. Key changes are outlined as follows:
• Plan Integration – Goals and objectives have been established for the updated MJHMP to align with current Planning Partner initiatives and programs, as well as to meet identified state priorities.
• Updated Hazards of Concern – The list of assessed hazards was updated to reflect the most current community experience and concerns.
• Socially Vulnerable Populations – The 2026 MJHMP update defines vulnerable populations based on the Planning Area’s demographic and geographic characteristics and includes a dedicated subsection for each identified hazard of concern. • Climate Change Impacts – The 2026 MJHMP update dedicates a subsection for each hazard of concern to the issue of climate change and its effects on state-identified climate-related hazards.
1.3 HOW TO USE THIS PLAN
The 2026 Palos Verdes Peninsula MJHMP was prepared to align with FEMA’s Local Mitigation Planning Policy Guide (April 2025), FEMA’s Local Mitigation Planning Handbook (June 2025), and the State of California planning requirements. The MJHMP is organized into two volumes as follows:
1.3.1 Volume 1
• Executive Summary
• Part 1 - Introduction and Planning Process
• Part 2 - Risk Assessment
• Part 3 - Mitigation Strategy
• Part 4 - Maintaining the Plan
• Appendix A – Public Outreach
• Appendix B – Hazard Selection
• Appendix C – Meeting Documentation
• Appendix D – Risk Assessment Methodology
• Appendix E – Federal and State Agencies, Programs, and Regulations • Appendix F – Plan Maintenance Agendas
• Appendix G – FEMA Approval and Planning Partner Adoption
1.3.2 Volume 2
• Federally required jurisdiction-specific elements, in annexes for each participating jurisdiction. • Description of the participation requirements confirmed by the CPT and HMPC.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Introduction 1-6
1.3.3 Planning Requirement Icons
Throughout this plan, FEMA’s local hazard mitigation planning requirements and state-specific compliance are identified using the icons below. These provide a pathway to show where the MJHMP meets each requirement.
FEMA Mitigation Plan Requirement – 44 CFR Part 201.6
Used to identify the requirements met for a local hazard mitigation plan.
California Senate Bill Compliance
Used to identify where the plan complies with California Senate Bills related to hazard mitigation planning.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-1
2. PLANNING PROCESS
Local Plan Requirement A1 – 44 CFR Part 201.6(c)(1)
The plan shall document the planning process used to develop the plan, including how it was prepared, who was involved in the process, and how the public was involved.
2.1 INTRODUCTION
The following section describes the overall process for the MJHMP, including how it was prepared, who was involved, and how stakeholders and the public participated. To adhere to the requirements of the DMA 2000 and ensure that the planning process received wide and robust support from the participating jurisdictions, regional and local stakeholders, and the public, the approach to the planning process and plan documentation included the following:
• The Palos Verde Peninsula MJHMP considers all natural hazards that pose a threat to the Planning Area. This satisfies the natural hazards requirements specified in DMA 2000 and Element B of FEMA’s Local Mitigation Planning Policy Guide (April 2025). • The City of Rolling Hills Estates served as the lead agency for the Palos Verde Peninsula MJHMP and selected a contract consultant, Black & Veatch, to assist with the development and implementation of the plan.
• A Core Planning Team (CPT) was formed to lead the planning effort, as shown in Table 2-1. • The City of Rolling Hills Estates invited all jurisdictions located within the Planning Area to participate in the MJHMP update. The four cities of the Palos Verde Peninsula and two special districts agreed to participate and meet participation expectations, where appropriate, as shown in Table 2-1.
• This MJHMP was developed and updated following the process outlined by DMA 2000, FEMA’s Local Mitigation Planning Handbook (June 2025), FEMA’s Local Mitigation Planning Policy Guide (April 2025), and the State of California planning requirements. Following these processes ensures that all requirements have been met and supports state and federal reviews of the MJHMP.
The planning process for this MJHMP update as shown below consisted of the following six steps:
1. Organize Resources.
2. Assess Risk.
3. Engage the Public.
4. Plan Mitigation Strategy.
5. Plan Maintenance Strategy.
6. Assemble and Adopt the Plan.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-12
2.2 DEFINING THE PLANNING AREA
The Planning Area consists of the Palos Verde Peninsula which includes the City of Palos Verdes Estates, City of Rancho Palos Verdes, City of Rolling Hills, City of Rolling Hills Estates, and Unincorporated Los Angeles County. Relevant Planning Area characteristics are described in Chapter 3 (Palos Verdes Peninsula Profile) and in each jurisdictional annex in Volume 2. The risk assessment for this MJHMP is performed for the entire Planning Area.
2.3 FUNDING
Funding for this MJHMP was fully funded through Cal OES HMGP DR-4683 with a local match.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-13
2.4 FORMATION OF THE PLANNING TEAMS
A successful planning effort includes active participation and buy-in from the whole community – individuals and communities, all levels of government, private and nonprofit sectors, non-governmental establishments, community lifelines, and members of the public.
CORE PLANNING TEAM HAZARD MITIGATION
PLANNING COMMITTEE PLANNING PARTNERSHIP
The Core Planning Team was
made up of key personnel from
the cities and discipline leads
from the City of Rolling Hills
Estate’s contract consultant,
Black & Veatch.
The Planning Committee
consisted of a variety of
personnel from Palos Verdes
Peninsula city departments and
agencies, local jurisdictions,
and stakeholders that guided
the cities and participating
jurisdictions through the
process of updating the
MJHMP.
The Planning Partnership
included jurisdictional
representatives seeking DMA
2000 compliance. They
participated throughout the
process, reviewed information,
provided input, informed the
risk assessment, developed
mitigation strategies, and
adopted the MJHMP.
2.4.1 Core Planning Team
The Core Planning Team was made up of discipline leads from the City of Rolling Hills Estate’s contract consultant, Black & Veatch, and key personnel from each of the cities.
Table 2-1 lists the cities’ Core Planning Team members. They were responsible for monitoring plan progress milestones and identifying input need for the Planning Committee and Planning Partnership.
2.4.2 Planning Committee
The Planning Committee consisted of a variety of personnel from City departments and agencies, local jurisdictions, and stakeholders that guided the Planning Partnership through the process of updating the MJHMP.
Table 2-1 lists the Planning Committee members. They were responsible for participating throughout the process, reviewing information, providing input, informing the risk assessment, and developing mitigation strategies.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-14
2.4.3 Planning Partnership
The Planning Partnership was made up of jurisdictional representatives seeking DMA 2000 compliance.
They were responsible for participating throughout the process, reviewing information and providing input, informing the risk assessment, developing mitigation strategies, and adopting the HMP.
The City of Rolling Hills Estates notified Planning Area municipalities and special districts of the planning process and invited them to participate. They were asked to formally notify the City by letter of intent to participate and to identify points of contact to represent the jurisdiction and participate throughout the planning process. The contacts each jurisdiction identified in the letter of intent to participate were informed of the planning process, attended meetings, provided direct input, and reviewed plan documents.
Table 2-1 lists the Planning Partnership members and Appendix C (Meeting Documentation) identifies the individuals who represented their jurisdictions during the planning effort. Members of the Planning Partnership were responsible for participating throughout the process, reviewing information, providing input, informing the risk assessment, and developing mitigation strategies.
Jurisdictional involvement is demonstrated through the completion of an annex in Volume 2 of this plan.
Each annex was developed with input gathered during the planning process and includes points of contact, risk assessments for relevant hazards, evaluation of capabilities for mitigation, identification and prioritization of mitigation measures, and ultimately, adoption of the updated plan through a resolution.
Table 2-1. Palos Verde Peninsula Hazard Mitigation Planning Participation Jurisdiction / Organization Name
Core Planning Team MemberPlanning Committee MemberPlanning Committee Member (Alternate)Ad Hoc CommitteePlanning Partnership Member City of Palos Verdes Estates
Kristen Jo, Emergency
Preparedness & Community
Outreach Coordinator
◼ ◼ ◼ ◼
City of Palos Verdes Estates George Gabriel, Deputy City Manager
◼ ◼
City of Rancho Palos Verdes
Luna Mohammad,
Emergency Management
Coordinator
◼ ◼ ◼ ◼
City of Rolling Hills Samantha Crew,
Management Analyst ◼ ◼ ◼ ◼
City of Rolling Hills Estates Jessica Slawson, Assistant to the City Manager ◼ ◼ ◼ ◼
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-15
Jurisdiction / Organization Name
Core Planning Team MemberPlanning Committee MemberPlanning Committee Member (Alternate)Ad Hoc CommitteePlanning Partnership Member Abalone Cove Landslide
Abatement District
Jim Knight, Retired, Former
Mayor
◼
Abalone Cove Landslide
Abatement District Gordon Leon ◼
City of Rancho Palos Verdes Deanna Fraley, Principal
Engineer
◼
City of Rancho Palos Verdes
Megan Barnes,Senior
Administrative Analyst
(PIO)
◼
City of Rolling Hills Estates Gabby Swain,
Administrative Aide (PIO) ◼
City of Rolling Hills Estates Whitney Berry,Senior
Planner ◼
Palos Verdes Peninsula Land
Conservancy
Cris Sarabia, Conservation
Director ◼
Palos Verdes Peninsula Unified
School District
Cheryl Dawson, Emergency
Preparedness Consultant ◼
Palos Verdes Peninsula Unified
School District
Brenna Terrones, Assistant
Superintendent ◼
PVPCERT, NART Georgiann Keller (Chair) ◼
Rolling Hills Community
Association Kathryn Bishop ◼
Southern California Edison Connie Turner, Regional
Manager – Public Affairs ◼
Southern California Gas Co. Ben Steinberger, Public
Affairs Advisor ◼
California Water Service Company Tracy Maestro,
Superintendent ◼
City of Rancho Palos Verdes Ara Mihranian, City
Manager
◼
City of Rancho Palos Verdes Paul Seo, City Council
Member ◼
City of Rolling Hills Estates Greg Grammer, City
Manager
◼
City of Rolling Hills Karina Banales, City
Manager
◼
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-16
Jurisdiction / Organization Name
Core Planning Team MemberPlanning Committee MemberPlanning Committee Member (Alternate)Ad Hoc CommitteePlanning Partnership Member City of Palos Verdes Estates David McGowan, City
Council Member ◼
City of Rolling Hills Estates Kerry Kallman, City
Manager
◼
City of Rolling Hills Velveth Schmitz, City
Council Member ◼
Black & Veatch Rob Flaner, Project
Manager
◼
Black & Veatch Megan Brotherton, Lead
Planner ◼
Black & Veatch Carol Baumann, Risk
Assessment Lead ◼
Black & Veatch Erin Schanen, Planner ◼
2.5 STAKEHOLDER COORDINATION AND INVOLVEMENT
Local Plan Requirement A2 – 44 CFR Part 201.6(b)(2)
The planning process shall include an opportunity for neighboring communities, local and regional agencies involved in hazard mitigation activities, and agencies that have the authority to regulate development, as well as businesses, academia and other nonprofit interests to be involved in the planning process.
Outreach to stakeholders was conducted in a timely manner and maintained throughout the planning process. This section outlines the stakeholders who were involved in the creation of this MJHMP and outlines their participation.
2.5.1 Types of Stakeholders
Stakeholders consist of individuals and groups that mitigation actions or policies affect. For this MJHMP, businesses, private organizations, public entities, and neighboring communities were identified and invited to participate. The Planning Partnership made conscientious efforts to ensure diverse regional, County, and local representation in the planning process.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-17
2.5.2 Stakeholder Participation
Throughout the entire planning process, stakeholders were invited to participate via email notifications informing them of the planning effort and giving them an opportunity to get involved. Stakeholders were invited to participate as follows:
• Participate as a member of the Steering
Committee and/or as a Planning Partner.
• Take a Public Hazard Awareness Survey.
• Attend Planning Committee meetings.
• Share public outreach information within their
organization.
• Comment on the draft plan.
Below is a summary of the stakeholders' involvement in
the planning process, demonstrating the extensive
outreach efforts made by the Planning Partnership. Key
elements of stakeholder outreach include the following:
• Seven stakeholders agreed to serve as members
of the Steering Committee.
• The web link to the draft plan was emailed to all
stakeholders and neighboring communities,
inviting them to comment on the draft plan.
Federal and State Agencies
The following section lists the government agencies that were involved during the planning process.
Table 2-2 describes how federal and state agencies participated in the Palos Verdes Peninsula MJHMP update. Those listed in the table below were directly or indirectly involved in the process and provided crucial information to update the plan.
Table 2-2. Federal and State Agencies
Agency/Department Federal State Participation
FEMA Region 9 ◼ FEMA provided updated planning guidance; provided summary and detailed NFIP data for
the Planning Area; presented preliminary
regulatory flood products to municipalities and
the public; and conducted plan review.
FEMA National Risk Index (NRI) ◼ FEMA’s NRI was used as a baseline for natural hazard selection for this MJHMP.
National Centers for Environmental
Information (NCEI)
◼ NCEI’s online tools were accessed to obtain
information regarding hazard identification,
hazard details, and risk assessments to
incorporate into the MJHMP update.
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Agency/Department Federal State Participation
CAL FIRE ◼ Provided updated maps for Local Responsibility Areas that were used in the wildfire risk
assessment.
Cal OES – Mitigation Planning
Division
◼ Oversaw the planning process; reviewed the
draft plan.
Local Stakeholders and Neighboring Communities
Area stakeholders and neighboring communities were invited to participate in the MJHMP update process. Agencies and organizations provided input in a variety of ways. Those that served on the HMPC and as a Planning Partner, that provided services to vulnerable populations, and that were informed of the planning process are noted in Table 2-1.
2.5.3 Draft Plan Review
All the entities listed above were provided an opportunity to review and comment on the draft plan during the public comment period, primarily through the link on the MJHMP web page. Each entity was sent an email informing them that the draft plan was available for comment and included a link to the web page and online comment tool. Additional invitations to review the draft plan were released through social media posts.
The public draft review period extended from February 12–25, 2026. TBD comments were received on the draft plan.
Upon completion of a public comment period, the complete draft plan was sent to the California Governor’s Office of Emergency Services (Cal OES) and FEMA Region 9 for a review to ensure program compliance.
2.6 PUBLIC PARTICIPATION
Local Plan Requirement A3 – 44 CFR Part 201.6(b)(1)
The planning process shall include an opportunity for the public to comment on the plan during the drafting stage and prior to plan approval.
An important component of the mitigation planning process involved public participation. Input from the public provides the Planning Partnership with a greater understanding of local concerns and increases the likelihood of successfully implementing mitigation actions by developing community “buy-in” from those directly affected by the decisions of Planning Area officials. Public awareness is a key component of a successful mitigation strategy and is aimed at making the community safer from the potential effects of hazards.
Public involvement during the development of the Palos Verdes Peninsula MJHMP was sought using a public survey, which permitted open comment; and a digital copy of the draft plan was made available on the project web page and advertised for public review and comment. Comments received were incorporated in the draft plan as applicable.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-19
2.6.1 Hazard Mitigation Plan Web Page
At the beginning of the planning process, a hazard mitigation web page was established on PVPReady.gov to provide information about the process. The web page was used to keep the public informed about milestones and public participation opportunities and to solicit input.
Figure 2-1. Hazard Mitigation Web Page
2.6.2 Public Meetings
Each of the Hazard Mitigation Planning Committee meetings was open and advertised for public attendance (Figure 2-2). Refer to Section 2.9, Plan Development Milestones, for descriptions and details of the Hazard Mitigation Planning Committee meetings.
2.6.3 Public Events
Peninsula-wide public events promoted the MJHMP planning process including the Prepared Peninsula Expo in October 2025, with hundreds of community members in attendance. Additionally, the local station RPVtv broadcasts interviews on the planning process (Figure 2-3).
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-20
Figure 2-2. Public Meeting Participation
Photo Credit: Megan Brotherton
Figure 2-3. Prepared Peninsula Expo Featuring Coverage by RPVtv
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-21
2.6.4 Public Survey
The CPT developed and posted a public survey early in the planning process. The survey was designed to capture information from members of the public. The survey was posted from August 2025 through January 2026. A link to the survey was posted on the planning web page and distributed through multiple social media platforms. A link to the electronic public survey was also shared with Planning Committee members, Planning Partners, and Stakeholders. RPVtv broadcast a public service announcement informing community members of the opportunity to provide input (RPVtv Public Service Announcement - "Palos Verdes Peninsula Hazard Mitigation Survey").
Figure 2-4. Survey Promotion on RPVtv
Summary of Survey Results
During the 6-month period that the survey was open, 431 members of the public completed the public survey. The complete survey and detailed results are included in Appendix A (Public Outreach).
Incorporation of the Public Survey Into the Hazard Mitigation Plan Survey participants, including those from socially vulnerable communities, suggested actions the Planning Partners should continue to do or should start doing to reduce or eliminate risk of future hazard events. Of those suggestions, all are included in the mitigation action plan, or are existing core capabilities that the Planning Partners will continue to carry out. Refer to Table 2-3 for examples of the suggestions and how they were incorporated in the MJHMP update.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-22
Table 2-3. Public Survey Comment Examples and MJHMP Incorporation Public Comment 2026 MJHMP Incorporation
TBD TBD
TBD TBD
2.6.5 Public Review Period
Members of the public were provided an opportunity to comment on the draft plan for 2 weeks in February 2026. The PVPReady.gov web page included a link to the draft plan and an online tool that allowed community members to submit comments. In addition to the website, the public comment period was promoted on social media.
2.7 IDENTIFICATION AND OUTREACH TO EQUITY PRIORITY COMMUNITIES Due to the demographic and geographic composition of the Palos Verdes Peninsula, the HMPC determined that those who may be more vulnerable to hazards include residents 65+ years of age, those with access and functional needs, and those who live in neighborhoods with only one point of evacuation.
These community members were included in the planning process through digital, social media, in-person, and broadcast outreach.
2.8 REVIEW AND INCORPORATION OF EXISTING PROGRAMS
Local Plan Requirement A4 – 44 CFR Part 201.6(b)(3)
Review and incorporation, if appropriate, of existing plans, studies, reports, and technical information.
The Planning Partnership utilized the most current technical information, plans, studies, and reports during the planning process to assist in hazard profiling, risk and vulnerability assessment, reviewing mitigation capabilities, and identifying, developing, and prioritizing mitigation strategies at the local levels.
• Overall Planning Process – The 2025 FEMA Local Mitigation Planning Policy Guide and Handbook were reviewed and used to develop this MJHMP. The 2023 California State HMP was reviewed for alignment with mitigation goals, identified hazards, risk assessments, and mitigation actions. In addition, neighboring jurisdiction mitigation plans were reviewed for alignment with identified hazards and mitigation actions.
• Risk Assessment – Asset and inventory data collected was used to complete the risk assessment of the MJHMP. This included local, state, and federal hazard technical information (e.g., US Geological Survey [USGS] earthquake data, CAL FIRE wildfire data, FEMA disaster declarations). Details of the data used, along with how the data was used, is presented in Chapter 1 and throughout the hazard profiles (Chapters 6 through 0). • Capability Assessment – Numerous plans, reports, regulations, codes, and technical information were obtained from the HMPC, and stakeholders involved in the planning process, as well as
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-23
through independent research conducted by the planning consultant. The Planning Partners were responsible for providing the inventory of their Planning and Regulatory capabilities in each jurisdictional annex in Volume 2, and noted relevant planning and regulatory documents as needed.
• Mitigation Strategy – The Planning Partnership developed nearly 200 mitigation actions to address the results of the risk assessment and input received from the public and local stakeholders. These actions considered the current capabilities of the Planning Partners to implement each strategy.
2.9 PLAN DEVELOPMENT MILESTONES
Table 2-4 summarizes the planning process activities, efforts, and key milestones conducted to prepare the MJHMP. Meeting documentation (e.g., presentations, agendas, meeting minutes) are located in Appendix C (Meeting Documentation). The table only identifies formal meetings held during the plan update; it does not reflect all planning activities conducted by individuals and groups throughout the planning process.
Table 2-4. Plan Development Milestones
Date Event Description Attendance
Support Contractor Secured N/A
Organize Resources CPT formed N/A
April 17, 2025 Project Kickoff Meeting • Introductions
• HMP Overview
• Scope & Schedule
• Core Planning Team
• Planning Committee
• Risk Assessment
• Planning Partnership
• County Department
• Responsibilities
• Communication Protocols
June 3, 2025 CPT Meeting #1 • HMPC Membership and
Coordination
• HMPC Kickoff Meeting
• GIS/Hazard Selection
• File Sharing Access
8 June 11, 2025 HMPC Meeting #1 • Welcome & Introductions • Hazard Mitigation Planning
Overview
• Role of the Planning
Committee
• Meeting Ground Rules
• Participating Planning Partners
• Confirm Hazards
• Public Outreach Strategy
23
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-24
Date Event Description Attendance
July 1, 2025 CPT Meeting #2 • GIS
• Landslide Methodology
• Public Outreach Strategy
• Community Lifelines
• Mitigation Goals
• HMPC Meeting Agenda
9 July 8, 2025 HMPC Meeting #2 • Welcome
• Approve June Meeting
Summary
• Confirm Community Outreach
Strategy
• Define Equity Priority
Communities
• Approve Community Lifelines
Recommendations
• Discuss Mitigation Goals
20 July 15, 2025 CPT Meeting #3 • Jurisdictional Annex Overview • Landslide Subcommittee
• Public Outreach
• GIS/Equity Priority
Communities
9 July 29, 2025 CPT Meeting #4 • Finalize Landslide
Subcommittee Membership
• Public Outreach
• Hazard Mitigation Goals
7 August 2025 Public Outreach • Public Survey Opens
August 12, 2025 Landslide Subcommittee
#1
• Introductions
• Landslide Risk Assessment
Methodology
• GIS/Data Request
9 August 26, 2025 CPT Meeting #5 • Landslide Subcommittee Meeting Takeaways
• Public Outreach Update
• SWOO Strategy & Mitigation
Catalog for Planning
Committee Input
• Annex Development Needs
7 September 9, 2025 CPT Meeting #6 • Planning Committee Meeting Agenda
• SWOO Exercise
7 September 10, 2025 HMPC Meeting #3 • Approve July Meeting Summary
• Community Outreach Strategy
Updates
• Landslide Subcommittee
Update
• Planning Partner Update
• Confirm Mitigation Goals
17 September 27, 2025 Public Outreach Rancho Palos Verdes “Wildfire Home Hardening Expo”
N/A
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-25
Date Event Description Attendance
October 7, 2025 CPT Meeting #7 • Public Outreach Coordination • Landslide Analysis Overview
• Landslide Subcommittee
Meeting Schedule
• SWOO Updates
6 October 15, 2025 Landslide Subcommittee
#2
• Landslide Approach
• Landslide Risk Assessment
Results
9 October 26, 2025 Public Outreach Palos Verde Peninsula “Prepared Peninsula Expo – Learn How to be
Disaster Ready”
300
October 21, 2025 CPT Meeting #8 • Hazard Map Review and Approval
• Landslide Subcommittee
Takeaways
• Draft Natural Hazard Risk
Assessment Results
• November Planning
Committee Meeting
• Phase 2 Planning Partner
Annex Workshop
• Ad Hoc Committee Meeting
Coordination
7 November 4, 2025 CPT Meeting #9 • Community Outreach
Summary
• HMPC Meeting Coordination
• Ad Hoc Committee Meeting
Coordination
6 November 18, 2025 CPT Meeting #10 • Ad Hoc Committee Meeting Coordination
• Public Survey
• HMPC Meeting Coordination
6 November 20, 2025 HMPC Meeting #4 • Approve September Meeting Summary
• Community Outreach Updates
• Schedule and Milestones
• Risk Assessment Results
• Mitigation Action Ideas
6 December 2, 2025 Mitigation Action Workshop • Purpose of the Mitigation Strategy
• Connecting to the Mitigation
Strategy
• Where to Focus
• Mitigation Actions to Consider
• Mitigation Action Worksheet
and Online Form
• Examples
7
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Planning Process 2-26
Date Event Description Attendance
December 3, 2025 Ad Hoc Committee Meeting • HMP Planning Process Overview
• Project Schedule and
Milestones
• Community Outreach
Initiatives
• Hazard Scenarios and Risk
Assessment Results
13 December 16, 2025 CPT Meeting #11 • Upcoming Schedule and Milestone Coordination
• Action Plan Development
7 January 2026 Public Outreach • Public Survey Closes 431 January 27, 2026 CPT Meeting #12 • Landslide Chapter Feedback • Public Survey Results Overview
• Plan Maintenance Strategy
7 February 10, 2026 CPT Meeting #14 TBD TBD
February 11, 2026 HMPC Meeting #5 • Approve September & November Meeting
Summaries
• Final MJHMP Input
Opportunity
• Public Comment Period
• Next Steps and Milestones
to Plan Approval
• Concluding Comments and
Appreciations
TBD
February 12-25, 2026 Public Outreach Public Comment Period N/A February 19, 2026 Public Outreach Peninsula Public Safety Committee Meeting
TBD
Month day, 2026 Plan Submittal to Cal OES Submittal of draft plan and plan review tool to Cal OES for review
and approval
N/A
Month day, 2026 Plan Submittal to FEMA
Region 9
Submittal of draft plan to FEMA
Region 9 by Cal OES
N/A
Month day, 2026 Approval Pending Adoption Approval Pending Adoption provided by FEMA Region 9
N/A
February - March 2026
Adoption City Council and District Board
adoption of draft plan
N/A
Month day, 2026 Approval Proof of adoption documentation submitted to FEMA Region 9 and
Cal OES
N/A
Month day, 2026 Approval Final approval of the plan by FEMA Region 9
N/A
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Palos Verdes Peninsula Profile 3-1
3. PALOS VERDES PENINSULA PROFILE
This section provides general information about the Planning Area, including its historical information, physical setting, general building stock, land use, population, demographics, population trends, and community lifelines. Analyzing this information leads to an understanding of the study area, including economic, structural, and population assets at risk, and of concerns that could be related to hazards analyzed in this plan (e.g., low-lying areas prone to flooding, high percentage of vulnerable persons in an area).
3.1 OVERVIEW
3.1.1 Historical Overview
The Palos Verdes Peninsula was inhabited by the Tongva people for thousands of years prior to European settlement. In subsequent centuries, the land was used for farming and mining and passed through the ownership of the Sepulveda family and various mortgage holders. In 1913, Frank A. Vanderlip acquired the entire 16,000-acre peninsula with the desire to develop an exclusive residential community. Although progress was slowed by the Great Depression and World War II, development advanced rapidly during the 1950s and 1960s.
On December 20, 1939, the City of Palos Verdes Estates was the first of the four cities in the Planning Area to become incorporated. In 1957, the Cities of Rolling Hills Estates and Rolling Hills became incorporated. Rancho Palos Verdes was the last City to become incorporated in 1973.
Development in the Planning Area is notably mostly residential with large lots, equestrian trails, and abundant open space. The Planning Area is known for its coastal views, rolling hills, and steep slopes.
The western and southern part of the Palos Verdes Peninsula is characterized by coastal bluffs and sea cliffs that range from approximately 100 to 300 feet high.
3.1.2 Jurisdictions
The Planning Area is made up of the Cities of Palos Verdes Estates, Rancho Palos Verdes, Rolling Hills, and Rolling Hills Estates. The Planning Area is bounded by the City of Torrance to the north and the San Pedro neighborhood of the City of Los Angeles to the southeast. The central portion of the Planning Area includes the unincorporated community known as Westfield/Academy Hills.
3.1.3 Government
The Planning Area is governed by five separate bodies: Los Angeles County which provides police and fire services and the general law Cities of Palos Verdes Estates, Rancho Palos Verdes, Rolling Hills, and Rolling Hills Estates which all have council-manager government structures. Palos Verdes Estates has its own police department.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Palos Verdes Peninsula Profile 3-2
3.2 PHYSICAL SETTING
This section describes the geography, land use, and land cover of the Planning Area.
3.2.1 Location
The Palos Verdes Peninsula is located in southwestern Los Angeles County and is bordered by the City of Torrance to the north, the San Pedro neighborhood of the City of Los Angeles to the east, and the Pacific Ocean to the south and west. The Peninsula forms a distinct geographic subregion within the South Bay area of Los Angeles County, characterized by elevated coastal hills and steep bluffs overlooking the Pacific Ocean. The Peninsula was once part of the Southern Channel Islands before becoming part of the California mainland. The 80-kilometer Palos Verdes Fault Line runs along the meeting place of the San Pedro Shelf and the San Pedro Basin and roughly forms the peninsula boundary.
3.2.2 Geography and Topography
The Palos Verdes Peninsula is situated south of the Pacific Coast Highway and west of Western Avenue (Highway 213). The landscape varies widely from the sandy beaches on the southern coast to the miniature Coast Range mountainous area of the Palos Verdes Hills on the northwestern side of the Planning Area, which peaks at 1,457 feet. The steep sea cliffs of this area form coastal bluffs and tidepools. The eastern part of the Planning Area features semi-rural rolling hills and scenic canyons.
The Palos Verdes Peninsula Land Conservancy manages over 1,700 acres of natural lands and 42 miles of public hiking trails. The Planning Area is also home to many beaches, coves, and City parks. The City of Rolling Hills Estates maintains over 20 miles of equestrian trails, and the Planning Area is renowned for its stables and equestrian opportunities.
The Palos Verdes Peninsula supports a mix of native and non-native vegetation shaped by its Mediterranean climate and unique geological history. Native vegetation includes coastal sage scrub, chaparral, and remnant grasslands, with species such as California Sagebrush, California Buckwheat, Toyon, and Coyote Brush. These plants help control erosion, limit wildfire, and lessen the impacts of drought. The coastal bluffs are home to salt-tolerant plants such as coastal sage scrub that provide habitat for the endangered Palos Verdes blue butterfly. While non-native grasses and ornamental trees like eucalyptus have altered portions of the landscape, ongoing restoration efforts led by local conservancies focus on rebuilding habitats for native fauna, reducing the presences of invasive species, and preserving the Peninsula’s ecological diversity.
3.2.3 Watersheds and Surface Waters
A watershed is a geographical area that directs precipitation and snowmelt towards creeks, streams, rivers, and ultimately outflow locations such as reservoirs, bays, and the ocean. Watersheds vary in size and configuration, encompassing anything from a small body of water or County to vast regions covering thousands of square miles with numerous waterways (National Ocean Service, 2024).
The Palos Verdes Peninsula forms a distinct coastal watershed region within southwestern Los Angeles County. Because of its elevated topography and peninsular landform, most surface runoff drains directly to the Pacific Ocean through a series of short, steep coastal watersheds. The Peninsula is generally
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Palos Verdes Peninsula Profile 3-3
divided into two HUC-12 equivalent watersheds the Santa Monica Bay Watershed and the Greater Dominguez Channel Watershed Management Area that is subdivided into Los Angeles Harbor Watershed and Machado Lake watershed (Peninsula WMG, 2019).
Watershed management on the Peninsula is coordinated through the Palos Verdes Peninsula Watershed Management Group (WMG) under the Regional MS4 Permit program. The Palos Verdes Peninsula WMG consists of the City of Rancho Palos Verdes, which serves as the coordinating agency for the Enhanced Watershed Management Program (EWMP) and Coordinated Integrated Monitoring Program (CIMP) Plan development, Los Angeles County Flood Control District, the County of Los Angeles and the cities of Palos Verdes Estates and Rolling Hills Estates (Los Angeles Regional Water Board, 2026). The City of Rolling Hills does not participate in the Peninsula EWMP; however, it does participate in the Peninsula CIMP (Los Angeles Regional Water Board, 2026). Figure 3-1 presents the watersheds found within the EWMP Watersheds with existing water quality monitoring sites.
Source: (Peninsula WMG, 2019)
Figure 3-1. Palos Verdes Peninsula EWMP Watersheds
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Palos Verdes Peninsula Profile 3-4
3.2.4 Climate
The Palos Verdes Peninsula is a mild Mediterranean climate characterized by warm, dry summers and cool, wetter winters. Average annual temperatures are approximately 63° F, and average annual precipitation ranges from 12 to 15 inches, with most rainfall occurring during the winter months (NOAA NCEI, 2025). Summers are generally warm and dry, with the highest monthly average being 85° F. The coolest month of the year is December, with an average high of 68° F and an average low of 49° F.
3.3 POPULATION AND DEMOGRAPHICS
Those who live in the Planning Area are the most important asset, and this MJHMP will assess risk to people and identify mitigation strategies to protect them, including underserved and socially vulnerable populations.
3.3.1 General Population
As of January 2025, the State of California Department of Finance reported the following population estimates for each of the cities:
• Rancho Palos Verdes: 40,727
• Palos Verdes Estates: 12,999
• Rolling Hills Estates: 8,545
• Rolling Hills: 1,677
Current and Historical Population
Table 3-1 shows past population estimates for the municipalities in the Planning Area from 2000 to 2024.
Over that time, California’s population grew by 17.4 percent (California Department of Finance, 2025).
The Planning Area’s population overall has experienced a decline since 2020, though the City of Rolling Hills Estates stands as an exception to this.
Table 3-1. Recent Population by Jurisdiction
Jurisdiction
2000
Population
2010
Population
2020
Population
2024
Population
City of Palos Verdes Estates 13,317 13,444 13,328 13,014 City of Rolling Hills Estates 7,657 8,064 8,232 8,557
City of Rancho Palos Verdes 41,043 41,654 42,150 40,831 City of Rolling Hills 1,867 1,867 1,735 1,673
Total 63,884 65,029 65,445 64,075
Source: (California Department of Finance, 2025)
Future Population Projections
According to the Southern California Association of Governments (SCAG) Connect SOCAL 2024 Report, The SCAG region’s annual growth has decreased every decade since the 1980s. The region is still adding new residents, but growth is expected to continue to slow. Los Angeles County is projected to grow
7.8 percent between 2019 and 2050.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Palos Verdes Peninsula Profile 3-5
3.3.2 Equity Priority Communities
Equity priority communities may be more at-risk during hazard events due to a variety of factors, such as their physical capacity to react or respond effectively, as well as their location and lack of access to emergency services. Those with greater vulnerability may experience more severe impacts during emergencies or disasters.
The identification of socially vulnerable populations and underserved communities within the Planning Area was emphasized throughout the planning process. Refer to Section 2.7 for more information on how vulnerable communities were identified and included in the planning process.
The Planning Partnership identified the following socially vulnerable populations and underserved communities:
• Demographic Vulnerability – Residents who are 65+ years of age and/or have access and functional needs.
• Evacuation Vulnerability – Residents who live in neighborhoods with only one point of access to an evacuation route.
Table 3-2. Vulnerable Populations Exposed to Hazard of Concern City
Total
Population
Demographic
Vulnerability
Population
Demographic
Vulnerability %
of Total
Population
Evacuation
Vulnerability
Population
Evacuation
Vulnerability
% of Total
Population
Palos Verdes Estates 12,999 0 0.0% 0 0.0%
Rolling Hills Estates 40,727 10,339 25.4% 5,723 14.1%
Rancho Palos Verdes 1,677 1,677 100.0% 1,677 100.0%
Rolling Hills 8,545 3,811 44.6% 2,840 33.2%
Total 63,948 15,827 24.8% 10,240 16.0%
3.4 DEVELOPMENT PROFILE
Local Plan Requirement B2—
44 CFR Part 201.6(c)(2)(ii)(C)
Local Plan Requirement E1—
44 CFR Part 201.6(d)(3)
The plan should describe vulnerability in terms of
providing a general description of land uses and
development trends within the community so that
mitigation options can be considered in future land
use decisions.
A local jurisdiction must review and revise its plan
to reflect changes in development.
3.4.1 Land Use
Land use describes the human use of land. It represents the economic and cultural activities (e.g., agricultural, residential, industrial, mining, and recreational uses) that are practiced at a given place.
Public and private lands frequently represent very different uses (U.S. EPA 2024). Land cover describes
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Palos Verdes Peninsula Profile 3-6
how much of an area is covered by forests, wetlands, impervious surfaces, agriculture, and other land and water types. Water types include wetlands or open water (National Ocean Service 2024).
Land use varies from land cover in that certain uses may not always be immediately apparent (e.g., land utilized for timber production without harvest for an extended period and wooded areas designated as wilderness may both appear as forested areas but serve different purposes) (U.S. EPA 2024).
Additional detail on land use and development trends for each of the municipal jurisdictions can be found in Volume 2 of this MJHMP.
Palos Verdes Estates
According to the City of Palos Verdes Estates General Plan (1973), the majority of land in the City is dedicated to single-family residential uses. Because commercial development within City limits is limited, residents rely on neighboring communities for most commercial services. According to the Palos Verdes Estates General Plan (2013-2021), at the time of the report, none of the vacant lots were suitable for multi-family development. The small number of vacant lots pose various constraints such as very high land costs, topographical challenges, and potential investment needed for grading or other modifications.
Rancho Palos Verdes
According to the City of Rancho Palos Verdes General Plan Land Use Element (2018), development is constrained by designated hazard areas. Residential uses represent the City’s predominant land use, followed by Open Space Preserve as the second most common. The City is the largest on the peninsula and houses many of the schools and other institutional land uses in the Planning Area. There are 18 public parks contributing to the second highest land use, Open Space Preserve.
There are several commercial centers in the City, though few opportunities for new commercial development exist. In recent years, planning efforts have increasingly emphasized open‑space preservation, hazard avoidance (particularly landslide areas), and infrastructure maintenance.
Rolling Hills
According to the City of Rolling Hills’ General Plan Land Use Element (1990), the City’s land is predominately used for low-density or very low density, single-family development. According to the Rolling Hills Housing Element (2021-2029), the City has vacancies rates of 5 percent (rental) and 9 percent (homeowner). The City does not have any commercial land use. At the time of this MJHMP development, the City was planning for residential development.
Rolling Hills Estates
According to the Rolling Hills Estates General Plan 2040, residential development is the City’s dominant land use, covering almost 60 percent of its total land area. Parks and recreation make up the second highest land use with nearly one-quarter of the land dedicated for open space and golf courses.
Commercial development makes up less than 5 percent of City land and is primarily concentrated along Silver Spur Road. This commercial area is home to the most commercial activity in the Planning Area.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Palos Verdes Peninsula Profile 3-7
At the time of the land use element update, new developments consisted of residential care facilities for seniors, mixed-use condominiums, and single-family homes, reflecting the City’s predominantly residential character.
3.4.2 General Building Stock
Current Building Stock
According to Los Angeles County Assessor records, 22,474 buildings are in the Planning Area, with a total replacement value of $24.1 billion. Table 3-3 shows the distribution of buildings by type of use within each of the Cities.
Table 3-3. Building Count by Occupancy Class
City
Building Count by Occupancy Class
ResidentialCommercialIndustrialAgricultureReligionGovernmentEducationTotal Palos Verde Estates 5,001 38 0 1 10 5 8 5,063
Rancho Palos Verdes 13,216 112 0 2 29 8 32 13,399
Rolling Hills 703 5 0 0 0 2 0 710
Rolling Hills Estates 3,132 122 0 14 18 1 15 3,302
Total 22,052 277 0 17 57 16 55 22,474
3.5 COMMUNITY LIFELINES
FEMA released initial guidance on the community lifelines concept in 2019 to describe the assets that enable the continuous operation of critical government and business functions and are essential to human health and safety or economic security. Lifelines are the most fundamental services in the community that, when stabilized, enable all other aspects of society to function. When disrupted, decisive intervention (e.g., rapid service re-establishment or employment of contingency response solutions) is required (FEMA, 2023a).
The Planning Partnership identified lifelines that support the Paolos Verde Peninsula before, during, and after hazard events. A summary of the critical facilities or lifelines located within the Planning Area is listed in Table 3-4 and shown on Figure 3-2.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Palos Verdes Peninsula Profile 3-8
Table 3-4. Community Lifelines in the Planning Area
City
CommunicationsEnergyFood, Hydration, ShelterHazardous MaterialsHealth and MedicalSafety and SecurityTransportationWater SystemsTotal Palos Verdes Estates 11 1 0 0 1 11 1 4 29
Rolling Hills Estates 174 3 0 0 7 34 0 13 231
Rancho Palos Verdes 1 0 0 0 0 4 0 1 6
Rolling Hills 12 2 0 0 8 24 0 6 52
Total 198 6 0 0 16 73 1 24 318
Figure 3-2. Planning Area Critical Facilities
Figure will be inserted in agency review draft.
3.5.1 Safety and Security
Safety and security lifelines include law enforcement/security (e.g., police stations, correctional facilities, site security), fire service, search and rescue, government service (e.g., emergency operation centers, government offices, schools), and community safety (e.g., flood control, protective actions).
3.5.2 Food, Hydration, Shelter
Food, hydration, and shelter lifelines include food (e.g., grocery stores, food banks), hydration (e.g., water supply chain, bottled water distribution), shelter, and agriculture.
These lifelines exist within the Planning Area, but GIS data was not available for a spatial analysis or mapping. Many of these facilities, including grocery stores, are part of the general building stock analysis.
Shelters, food distribution centers, and cooling centers are included in the safety and security lifeline category (e.g., library, religious institution).
3.5.3 Health and Medical
Health and medical lifelines include medical care (e.g., hospitals, pharmacies, long-term care), public health (e.g., health surveillance, behavioral health, labs), patient movement (e.g., emergency medical service), fatality movement, and medical supply chain.
3.5.4 Energy
Energy lifelines include power grid (e.g., generation systems, transmission systems, distribution systems) and fuel (e.g., refineries, fuel storage, pipelines, gas stations).
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Palos Verdes Peninsula Profile 3-9
3.5.5 Communication
Communication lifelines include infrastructure (e.g., wireless, cable systems, television/radio, internet), alerts/warnings/messages, 911 and dispatch, responder communications, and finance (e.g., banks and electronic payment processing).
3.5.6 Transportation
Transportation lifelines include highway/roadway/motor vehicle (e.g., roads, bridges), mass transit, railway (e.g., freight, passenger), aviation, and maritime.
3.5.7 Hazardous Materials
Hazardous materials lifelines include facilities and HAZMAT, pollutants, or contaminants.
3.5.8 Water Systems
Water systems lifelines include potable water infrastructure (e.g., intake, treatment, storage, distribution) and wastewater management (e.g., collection, storage, treatment, discharge).
3.6 ECONOMY
3.6.1 Industry, Businesses, and Institutions
The Planning Area is largely residential, with most residents either commuting elsewhere for work, working from home, or retired. Because affordable housing options are scarce, many people employed on the peninsula live in surrounding communities.
Educational services, health care and social assistance, and professional, scientific, and management, and administrative and waste management services are the two largest industries in the Planning Area.
Table 3-5. Principal Employers in the Planning Area
Principal Employer Industry Location
UCLA Education Rancho Palos Verdes
Palos Verdes Peninsula High School Education Rolling Hills Estates Academy of Foreign Languages Education Rolling Hills Estates Rancho Vista Elementary School Education Rolling Hills Estates Ridgecrest Intermediate School Education Rancho Palos Verdes Point Vicente Elementary School Education Rancho Palos Verdes Miraleste Intermediate School Education Rancho Palos Verdes Soleado Elementary School Education Rancho Palos Verdes Vista Grande Elementary Education Rancho Palos Verdes
Dodson Middle School Education Rancho Palos Verdes
School of Skills Corp Education Rancho Palos Verdes
Montemalaga Elementary School Education Palos Verdes Estates Palos Verdes High School Education Palos Verdes Estates
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Palos Verdes Peninsula Profile 3-10
Principal Employer Industry Location
Valmonte Elementary School Education Palos Verdes Estates Palos Verdes Peninsula Unified School District
Office
Education Palos Verdes Estates
Institute of Internal Auditors Offices of Physicians Palos Verdes Estates Table 3-6 summarizes the breakdown of industry types in the Planning Area according to the US Census 5-year American Community Survey (2019-2023).
Table 3-6. Employment in Planning Area by Industry Sector Percentages Jurisdiction
Agriculture, Forestry, Fishing and Hunting, MiningConstructionManufacturingRetail TradeTransportation and Warehousing, UtilitiesFinance and Insurance, Real Estate, Rental and LeasingProfessional, Scientific, Management and Administrative, Waste Management ServicesEducational Services, Health Care and Social AssistanceArts, Entertainment, Recreation, Accommodation and Food ServicesOther Services (except Public Administration)Public Administration Palos Verdes
Estates 0.4% 3.9% 11.7% 5.7% 1.8% 17.7% 23.4% 17.4% 3.4% 1.5% 2.9% Rancho Palos
Verdes 0.4% 2.7% 11.5% 6.6% 9.0% 8.8% 19.3% 20.9% 4.2% 2.8% 4.6% Rolling Hills 0.5% 0.5% 7.5% 7.3% 1.5% 15.7% 23.2% 26.7% 5.8% 3.0% 0% Rolling Hill
Estates 0.4% 3.2% 11.0% 2.2% 3.4% 10.5% 14.7% 27.3% 9.8% 9.9% 1.7% Source: US Census 5-year American Community Survey (2019-2023).
Based on the State of California Employment Development Department, California’s 2024 unemployment rate was 5.5 percent. All four municipalities in the Planning Area reported lower unemployment rates.
The local economic conditions during the COVID pandemic may contribute to fluctuations in employment within 2020 through 2022.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Palos Verdes Peninsula Profile 3-11
Source: (U.S. Census, 2025)
Figure 3-3. Recent Unemployment Rates for California and the Planning Area 0%
2%
4%
6%
8%
10%
12%
2015 2016 2017 2018 2019 2020 2021 2022 2023 2024
Unemployement Rate
State of California
City of Rolling Hills
City of Rolling Hills Estates
City of Palos Verdes Estates
City of Rancho Palos Verdes
Part 2
Risk Assessment
Fred Hesse, Jr. Community Park, Rancho Palos Verdes, (Photo Credit: Megan Brotherton) Page 207 of 675 Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Hazards of Concern 4-1
4. HAZARDS OF CONCERN
4.1 WHAT IS A HAZARD OF CONCERN?
Defining the hazards that present the greatest risk to the Planning Area is the first step in assessing overall risk to the community. The CPT and PC reviewed available information to determine what types of hazards may affect the Planning Area, how often they can occur, and their potential severity.
Natural hazards are eligible for FEMA HMA grant funding and generally occur because of natural processes. Some natural hazards may also be caused by humans, such as wildfire. Human-caused hazards are not reviewed by FEMA for plan approval and are not eligible for FEMA HMA grant funding.
The CPT and PC chose to add them in the MJHMP because of their current and potential impact on the Planning Area and to align with other local plans and programs.
4.2 FEDERAL DISASTER DECLARATIONS
Federal disaster declarations are typically issued for hazard events that cause more damage than state and local governments can handle without assistance from the federal government, although no specific dollar loss threshold has been established for these declarations. A presidential disaster declaration puts federal recovery programs into motion to help disaster victims, businesses, and public entities. Some of the programs are matched by state programs. Review of presidential disaster declarations helps establish the probability of reoccurrence for each hazard and identify targets for risk reduction. Federal disaster declarations, authorized by the Stafford Act, include the following three main types:
• DR (Major Disaster) for large-scale events needing extensive aid. • EM (Emergency) for supplemental assistance to save lives and property. • FM (Fire Management) for fires threatening destruction.
Table 4-1 summarizes the Los Angeles County federal disaster declarations between 2019 and 2025.
Table 4-1. Federal Disaster Declarations in Los Angeles County Disaster Number Event Date Start Date Incident Type Title FM-5293-CA October 10, 2019 Fire Saddleridge Fire
FM-5296-CA October 24, 2019 Fire Tick Fire
FM-5297-CA October 28, 2019 Fire Getty Fire
DR-4482-CA January 20, 2020 Biological COVID-19 Pandemic EM-3428-CA January 20, 2020 Biological COVID-19
DR-4569-CA September 4, 2020 Fire Wildfires
FM-5374-CA September 13, 2020 Fire Bobcat Fire
DR-4683-CA December 27, 2022 Flood Severe Winter Storms, Flooding, Landslides, and Mudslides
EM-3591-CA January 8, 2023 Flood Severe Winter Storms, Flooding, and Mudslides
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Hazards of Concern 4-2
Disaster Number Event Date Start Date Incident Type Title DR-4699-CA February 21, 2023 Severe Storm Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides
EM-3592-CA March 9, 2023 Flood Severe Winter Storms, Flooding, Landslides, and Mudslides
DR-4769-CA January 31, 2024 Severe Storm Severe Winter Storms, Tornadoes, Flooding, Landslides, and Mudslides
FM-5537-CA September 10, 2024 Fire Bridge Fire
FM-5548-CA December 10, 2024 Fire Franklin Fire
FM-5551-CA January 7, 2025 Fire Hurst Fire
FM-5550-CA January 7, 2025 Fire Eaton Fire
FM-5549-CA January 7, 2025 Fire Palisades Fire
DR-4856-CA January 7, 2025 Fire Wildfires and Straight-Line Winds FM-5605-CA August 7, 2025 Fire Canyon Fire
Source: (FEMA, 2025)
4.3 NATURAL HAZARDS OF CONCERN AND HAZARDS OF INTEREST
Based on a review of the 2023 California State Hazard Mitigation Plan, the National Risk Index, prior hazard mitigation plans among the Planning Partnership, and input from the Steering Committee, seven hazards, listed alphabetically, were identified as natural hazards of concern affecting the Palos Verdes Peninsula and will be addressed in this plan update:
Drought Heat Wave Strong Wind
Earthquake Landslide Wildfire
Flood
Four hazards of interest listed below are discussed in a narrative but not fully assessed in the plan.
Groundwater Seepage Human-Caused
Hazardous Materials Utility Related
Please refer to Appendix B for a complete comparison of hazards included in the 2023 California State Hazard Mitigation Plan, the prior hazard mitigation plans from Planning Partnership, and this plan update.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Risk Assessment Methodology and Tools 5-1
5. RISK ASSESSMENT METHODOLOGY AND
TOOLS
5.1 ASSESSING RISK
In hazard mitigation planning, risk is the potential for damage or loss when natural hazards interact with people or assets, such as buildings, infrastructure, and resources. A risk assessment is a process used to identify potential hazards and analyze what could happen if a disaster or hazard occurs. It involves a data-driven analysis to identify potential hazards, what could happen if hazards occur, and determine vulnerabilities to hazards (FEMA, 2023).
The risk assessment process focuses on three main elements – hazard identification, exposure identification, and vulnerability identification and loss estimation.
5.2 RISK ASSESSMENT TOOLS
Local Plan Requirement A4 – 44 CFR Part 201.6(b)(3)
Review and incorporation, if appropriate, of existing plans, studies, reports, and technical information.
For this MJHMP, geographic information system (GIS) and FEMA’s Hazus software were used to conduct the risk assessment.
5.2.1 Mapping
GIS tools provide a mechanism to perform quantitative analysis. Hazards that have specified geographic boundaries permit analysis using GIS. These hazards include the following:
• Earthquake
• Flood (including sea level rise and tsunami)
• Landslide
• Wildfire
5.2.2 Modeling
FEMA’s Hazus Model 6.1 was used to evaluate the following hazards:
• Earthquake—A Level 2 analysis was performed to assess earthquake exposure and vulnerability for four scenarios: Compton M7.45, Palos Verdes M7.38, Redondo Canyon alt 2 M6.65, and the 100-yr probabilistic. The Hazus methodology uses ground motion and ground failure fragility curves to estimate damage state probabilities which are then used to estimate losses at the structure level. • Flood—A Level 2 user-defined analysis was performed for general building stock and critical facilities and infrastructure in flood zones. The effective FEMA flood mapping for the Planning Area was used
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Risk Assessment Methodology and Tools 5-2 to delineate flood hazard areas and estimate potential losses from the 1 percent annual chance flood event. To estimate damage that would result from a flood, Hazus uses predefined relationships between flood depth at a structure and resulting damage, with damage given as a percent of total replacement value. Curves defining these relationships have been developed for damage to structures and for damage to typical contents within a structure. By inputting flood depth data, estimated first floor elevations, and known property replacement cost values, dollar-value estimates of damage were generated.
• Landslide—Hazus does not model landslide, however, a Level 3 approach using Hazus protocols for a user-defined analysis was performed for general building stock in the deep-seated landslide hazard areas to estimate loss. Refer to Appendix D for a detailed description of the landslide hazard analysis methodology.
Overview
FEMA developed the Hazards U.S., or Hazus, model in 1997 to estimate losses caused by earthquakes and identify areas that face the highest risk and potential for loss. Hazus was later expanded into a multihazard methodology with new models for estimating potential losses from hurricanes and floods. The use of Hazus for hazard mitigation planning offers the following numerous advantages:
• Provides a consistent methodology for assessing risk across geographic and political entities. • Provides a way to save data so that it can readily be updated as population, inventory, and other factors change and as mitigation planning efforts evolve. • Facilitates the review of mitigation plans because it helps to ensure that FEMA methodologies are incorporated.
• Supports grant applications by calculating benefits using FEMA definitions and terminology. • Produces hazard data and loss estimates that can be used in communication with local stakeholders.
• Is administered by the local government and can be used to manage and update a HMP throughout its implementation.
Hazus is a GIS-based software program used to support risk assessments, mitigation planning, and emergency planning and response. It provides a wide range of inventory data, such as demographics, building stock, community lifelines, transportation and utility lifeline, and multiple models to estimate potential losses from natural disasters. The program can be used to map hazard data and the results of damage and economic loss estimates for buildings and infrastructure.
Level of Detail for Evaluation
Hazus provides default data for inventory, vulnerability and hazards; this default data can be supplemented with local data to provide a more refined analysis. The model can carry out the following three levels of analysis, depending on the format and level of detail of information about the Planning Area:
• Level 1—All of the information needed to produce an estimate of losses is included in the software’s default data. This data is derived from national databases and describes in general terms the characteristic parameters of the Planning Area.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Risk Assessment Methodology and Tools 5-3 • Level 2—More accurate estimates of losses require more detailed information about the Planning Area. To produce Level 2 estimates of losses, detailed information is required about local geology, hydrology, hydraulics and building inventory, as well as data about utilities and critical facilities. This information is needed in a GIS format. • Level 3—This level of analysis generates the most accurate estimate of losses. It requires detailed engineering and geotechnical information to customize it for the Planning Area.
5.3 RISK ASSESSMENT APPROACH
This plan evaluated risks associated with each identified hazard for the Planning Area. Each hazard was profiled using the following steps:
• Identify and profile each hazard – The following information is given for each hazard of concern:
o Description of the Hazard: Defining the hazard and a discussion of potential impacts. o Location: Geographic areas most affected by the hazard. o Extent: Measuring the intensity of the hazard, warning time for preparations, and the reasonable worst-case scenario.
o Previous Occurrences: Summary of past events that have impacted the Planning Area. o Future Occurrences: Probability estimates, including potential frequency and intensity shifts caused by climate change and population and development trends. • Determine exposure to each hazard – One of the following assessment approaches was used, depending on the type of information available for the hazard:
o Quantitative assessment—Performed when numerical data are available to define risk.
Available numerical hazard data may include financial impact and probability. o Qualitative assessment—Uses words to describe and categorize the likelihood and consequences of a risk when numerical data are unavailable. • Assess the vulnerability of exposed facilities – Vulnerability of exposed structures and infrastructure was evaluated by estimating the probability of occurrence of each event and assessing structures, facilities, and systems that are exposed to each hazard o Impact on Life, Health, and Safety
o Impact on General Building Stock
o Impact on Community Lifelines
o Impact on the Economy
o Impact on Historic and Cultural Resources
o Impact on Natural Resources
o Change in Vulnerability Since the Previous HMPs
• Identify potential mitigation opportunities – A range of potential opportunities for mitigating each hazard is included for jurisdictions to consider during the development of their mitigation strategies.
o Community: Mitigation actions that can be implemented by the general public. o Organizational: Mitigation actions that can be implemented by businesses and nonprofits. o Government: Mitigation actions that can be implemented by local governments.
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5.4 SOURCES OF DATA USED IN RISK ASSESSMENT
Hazard information and data were collected for all hazards from a variety of sources, described in the sections below.
5.4.1 Building and Cost Data
Parcel and building information from the Los Angeles County Assessor were used to compile a detailed, Planning Area-wide structure inventory including replacement costs. Replacement cost is the cost to replace the entire structure with one of equal quality and utility. Replacement cost is based on industrystandard cost-estimation models published in RS Means Square Foot Costs. It is calculated using the RS Means square foot cost for a structure, which is based on the Hazus occupancy class (i.e., multi-family residential or commercial retail trade), multiplied by the square footage of the structure from the tax assessor data. The construction class and number of stories for single-family residential structures also factor into determining the square foot costs.
5.4.2 Community Lifelines
An inventory of critical facilities and infrastructure was compiled from city, county, state, and national datasets. The facilities were categorized by FEMA’s Community Lifelines: Safety and Security; Food, Hydration, Shelter; Health and Medical; Energy; Communications; Transportation; Hazardous Material; and Water Systems. To protect individual privacy and the security of assets, information is presented in aggregate, without details about specific individual properties or facilities.
5.4.3 Population
2020 Census block-level data, provided with Hazus, was used to estimate the total population in each Planning Area. This data was also used to calculate the exposed population, displaced population and shelter needs for each hazard scenario.
Equity Priority Communities
Vulnerable communities for mitigation planning are defined through three categories: 65+ years of age, access and functional needs, and residents who live in neighborhoods with only one point of access to an evacuation route. In preparation for spatial overlays with the hazard data, the Planning Area was divided into three city boundaries for each member of the Planning Partnership.
Refer to Appendix D for a detailed description of the equity priority community methodology.
5.4.4 Hazus Data Inputs
The following hazard datasets were used for the Hazus analyses conducted for the risk assessment:
• Earthquake—ShakeMap data from the USGS Building Seismic Safety Council 2014 Event Set were used for the analysis of this hazard. This set of ShakeMap earthquake scenarios is the authoritative USGS collection for the continental United States. The scenario fault ruptures are derived from the latest National Seismic Hazard Model. Liquefaction zones and landslide susceptibility data from the California Geological Survey (CGS) was also incorporated into the Hazus model to replace the default data.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Risk Assessment Methodology and Tools 5-5 • Flood—A flood depth grid generated using the effective FEMA Digital Flood Insurance Rate Map (DFIRM), and USGS digital elevation model (DEM) data, was incorporated into the Hazus model.
5.4.5 Other Local Hazard Data
Local sources used in the risk and vulnerability assessment include the following:
• Landslide—Please refer to Appendix D for a full description of the data and methodology. • Sea Level Rise— Sea-level rises of 25 cm and 200 cm with 100-year storm surge data were obtained from the Our Coast Our Future website. These data were developed using USGS’ Coastal Storm Modeling System (CoSMoS) approach which projects coastal flooding due to both sea level rise and coastal storms driven by climate change. • Tsunami—An exposure analysis was conducted using tsunami hazard area data provided by the California Department of Conservation.
• Wildfire—An exposure analysis was conducted using fire hazard severity zones data from CAL FIRE. These zones were mapped based on fuel loading, slope, fire weather, and other relevant factors including winds. The zones are classified as Moderate, High, or Very High fire hazard.
5.4.6 Data Source Summary
Table 5-1 describes the data used for spatially-based exposure and vulnerability assessments.
Table 5-1. Data Source Summary
Data Source Date(s) Format(s)
City and Unincorporated
Boundaries (Legal)
Los Angeles Co. 2024 Digital (GIS) format
Countywide Building Outlines Los Angeles Co. 2025 Digital (GIS) format Los Angeles County Parcels Los Angeles Co. 2025 Digital (GIS) format Building replacement costs RS Means 2024 Digital (tabular) format American Community Survey
Evacuation routes
Compton M7.45 ShakeMap USGS 2017 Digital (GIS) format
Palos Verdes M7.38
ShakeMap
USGS 2017 Digital (GIS) format
Redondo Canyon alt 2 M6.65
ShakeMap
USGS 2017 Digital (GIS) format
CGS Map Sheet 48: Shearwave Velocity in Upper 30m
of Surficial Geology
(Vs30)/NEHRP Soils
CGS 2015 Digital (GIS) format
Liquefaction Zones CGS 2021 Digital (GIS) format
Digital Flood Insurance Rate
Map (effective 6/2/2021; last
LOMR 12/27/2024)
FEMA 2024 Digital (GIS) format
Projected flood exposure
data from the USGS Coastal
Our Coast Our Future 2018 Digital (GIS) format
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Risk Assessment Methodology and Tools 5-6 Data Source Date(s) Format(s)
Storm Modeling System
(CoSMoS v3.0) – 25cm with
100-year storm surge
Projected flood exposure
data from the USGS Coastal
Storm Modeling System
(CoSMoS v3.0) – 200cm with
100-year storm surge
Our Coast Our Future 2018 Digital (GIS) format
Tsunami Hazard Area Map,
Los Angeles County
CA Dept of
Conservation
2021 Digital (GIS) format
Landslide Catalog NASA 2019 Digital (GIS) format
CA Landslide Inventory CGS 2022 Digital (GIS) format
Redondo Beach Study CGS 1999 PDF format
San Pedro Study CGS 1999 PDF format
Torrance Study CGS 1999 PDF format
Percent Change in
Displacement Rate Map
Cotton, Shires and
Associates, Inc. 2024-2025 PDF format
CGS Landslide Zones CGS Downloaded 2025 Digital (GIS) format Fire Hazard Severity Zones in
Local Responsibility Areas
CAL FIRE 2025 Digital (GIS) format
Police Stations Hazus v6.1 Downloaded 2025 Digital (GIS) format Fire Stations Hazus v6.1 Downloaded 2025 Digital (GIS) format Emergency Centers Hazus v6.1 Downloaded 2025 Digital (GIS) format Municipal Services Los Angeles Co. Downloaded 2025
Schools, Colleges &
Universities
Los Angeles Co. Downloaded 2025 Digital (GIS) format
Schools Hazus V6.1 Downloaded 2025 Digital (GIS) format Electric Power Facilities Los Angeles County Digital (GIS) format Highway Bridges Hazus v6.1 Downloaded 2025 Digital (GIS) format Sewer Pump Stations Los Angeles Co. Downloaded 2025 Digital (GIS) format
5.5 DATA LIMITATIONS
Loss estimates, exposure assessments, and hazard-specific vulnerability evaluations rely on the best available data and methodologies. Uncertainties are inherent in any loss estimation methodology and arise in part from incomplete scientific knowledge concerning natural hazards and their effects on the built environment.
Uncertainties also result from the following:
• Approximations and simplifications necessary to conduct such a study. • Incomplete or dated inventory, demographic, or economic parameter data. • The unique nature, geographic extent, and severity of each hazard.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Risk Assessment Methodology and Tools 5-7 • Mitigation measures already employed by the participating municipalities. • The amount of advance notice residents have to prepare for a specific hazard event. • Uncertainty of climate change projections.
Hazus currently represents the industry best management practice for assessing risk in support of hazard mitigation planning. However, the Hazus model is limited by the availability of data to support its working components. The model makes assumptions where firm data are not available. Assumptions are used, for example, to estimate ground deformation caused by liquefaction. These model limitations can lead to an understatement or overstatement of risk.
These factors can result in a range of uncertainty in loss estimates, possibly by a factor of two or more.
Therefore, potential exposure and loss estimates are approximate. These results do not predict precise results and should be used to understand relative risk. Over the long term, the Planning Partnership will collect additional data to update and refine existing inventories to assist in estimating potential losses.
Potential economic loss is based on the present value of the general building stock utilizing best available data. The Planning Partnership acknowledges significant impacts may occur to critical facilities and infrastructure as a result of these hazard events causing great economic loss. However, monetized damage estimates to critical facilities and infrastructure, and economic impacts were not quantified and require more detailed loss analyses. In addition, economic impacts to industry such as tourism and the real-estate market were not analyzed.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Drought 6-1
6. DROUGHT
6.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.
6.1.1 Description of the Hazard
Defining the Hazard
Drought is defined as a deficiency in precipitation over an extended period that results in a water shortage (National Integrated Drought Information System, n.d.). It is a gradual phenomenon and occurs slowly over a period of time (California Governor's Office of Emergency Services, 2024). Drought can have devastating impacts on communities due to its cascading impacts, including but not limited to negative impacts on public health, tree mortality, water quality, and energy as well as increased wildfire risk.
The occurrence of drought is a normal phase in the climate cycle of most regions, originating from a deficiency of precipitation over an extended period, usually a season or more. This leads to a water shortage for some activity, group, or environmental sector. Drought can be characterized based on the following (National Integrated Drought Information System, n.d.):
• Meteorological Drought – When dry weather patterns dominate an area. • Hydrological Drought – When low water supply becomes evident in the water system. • Agricultural Drought – When crops become affected by drought. • Socioeconomic Drought – When the supply and demand of various commodities is affected by drought.
• Ecological Drought – When natural ecosystems are affected by drought.
Cause of the Hazard
Droughts originate from a deficiency of precipitation resulting from an unusual weather pattern. If the weather pattern lasts a short time (a few weeks or a couple of months), the drought is considered shortterm. If the weather pattern becomes entrenched and the precipitation deficits last for several months or years, the drought is considered long-term. It is possible for a region to experience a long-term pattern that produces drought, and to have short-term changes that result in wet spells within the long-term pattern. Likewise, it is possible for a long-term wet pattern to be interrupted by weather spells that result in short-term drought (National Integrated Drought Information System, n.d.).
Drought can be caused by various atmospheric conditions such as climate change, ocean temperatures, changes in the jet stream, and changes in the local landscape (National Aeronautics and Space Administration, n.d.). Droughts are long-term climatic patterns that emerge from complex interactions among global weather patterns. Persistent, upper-level high-pressure systems along the West Coast
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Drought 6-2
result in warm, dry air and reduced precipitation. Anomalies of precipitation and temperature may last from several months to several decades. How long they last depend on interactions between the atmosphere and the oceans, soil moisture and land surface processes, topography, internal dynamics, and the accumulated influence of global weather systems.
Summary of Potential Impacts
Drought can have a widespread impact on the environment and the economy, although it typically does not result in loss of life or damage to structures, as do other natural disasters.
The National Drought Mitigation Center uses three categories to describe likely drought impacts (National Integrated Drought Information System, n.d.):
• Economic Impacts—These impacts of drought cost people (or businesses) money. Farmers’ crops are destroyed; low water supply necessitates spending on irrigation or drilling of new wells; water-related businesses (such as sales of boats and fishing equipment) may experience reduced revenue.
• Environmental Impacts—Plants and animals depend on water. When a drought occurs, their food supply can shrink, and their habitat can be damaged.
• Social Impacts—Social impacts include public safety, health, conflicts between people when there is not enough water to go around, and changes in lifestyle.
The demand that society places on water systems and supplies—such as expanding populations, irrigation, and environmental needs—contributes to drought impacts. Drought can lead to difficult decisions regarding the allocation of water, as well as stringent water use restrictions, water quality problems, and inadequate water supplies for fire suppression. There are also issues such as growing conflicts between agricultural uses of surface water and in-stream uses, surface water and groundwater interrelationships, and the effects of growing water demand on uses of water.
Vulnerability of an activity to drought depends on its water demand and the water supplies available to meet the demand. The impacts of drought vary between sectors of the community in both timing and severity (National Integrated Drought Information System, n.d.):
• Water supply—The water supply sector encompasses drinking water systems that are affected when a drought depletes groundwater supplies due to reduced recharge from rainfall. • Agriculture and commerce—Impacts on the agriculture and commerce sectors include the reduction of crop yield and livestock sizes due to insufficient water supply for crop irrigation and maintenance of ground cover for grazing. In areas that depend on goods from agriculture and livestock, impacts may include increased prices for these commodities. • Environment, public health, and safety—The environmental, public health, and safety sector focuses on wildfires that are both detrimental to the ecosystem and hazardous to the public. It also includes the impact of desiccating streams, such as the reduction of in-stream habitats for native species.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Drought 6-3
Cascading Hazard Impacts
The cascading impact most associated with drought is wildfire. A prolonged lack of precipitation dries out vegetation, which becomes increasingly susceptible to ignition as the duration of the drought extends.
Drought is also often accompanied by extreme heat, exposing people to the risk of sunstroke, heat cramps, and heat exhaustion. Pets and livestock are also vulnerable to heat-related injuries.
6.1.2 Location
A drought is a regional event that is not confined to geographic boundaries; it can affect several areas at once and range in severity across those areas. Drought that affects the Planning Area would affect the entirety of the area simultaneously and has the potential to impact every person, directly or indirectly, as well as adversely affect the local economy. A drought’s impact can depend on climate zone, type of water supply available, and water users’ ability to manage drought impacts. Los Angeles County depends on local and imported water in highly drought sensitive areas such as the Sierras, Los Angeles River, San Gabriel River, and Colorado River for its water supply (Los Angeles County Public Works, n.d.).
In California, one dry year does not normally constitute a drought. The State’s extensive system of water supply infrastructure, which includes reservoirs, groundwater basins, and interregional conveyance facilities, are designed to mitigate the effects of short-term dry periods for most water users (DWR, n.d.).
However, prolonged dry periods still lead to water shortage emergencies.
6.1.3 Extent
Measuring Intensity
Several quantitative methods exist for measuring drought in the United States. How these indices measure drought depends on the drought classification and the region being considered. Droughts are dynamic, and locations of the State susceptible to drought can change monthly.
U.S. Drought Monitor
The U.S. Drought Monitor assesses multiple numeric measures of drought to depict the drought conditions and locations across the United States. The U.S. Drought Monitor uses five drought intensity categories, D0 through D4, to identify areas of drought. These categories are shown on Figure 6-1.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Drought 6-4
Source: (U.S. Drought Monitor, 2025)
Figure 6-1. U.S. Drought Monitor Categories
National Oceanic and Atmospheric Administration Drought Indices National Oceanic and Atmospheric Administration (NOAA) has developed several indices to measure drought impacts and severity and to map their extent and locations:
• The Crop Moisture Index measures short-term drought weekly to assess impacts on agriculture. • The Palmer Z Index measures short-term drought on a monthly scale. • The Palmer Drought Severity Index is based on long-term weather patterns. The intensity of drought in a given month is dependent on current weather plus the cumulative patterns of previous months. Weather patterns can change quickly, and the Palmer Drought Severity Index can respond fairly rapidly.
• The Palmer Hydrological Drought Index quantifies hydrological effects (reservoir levels, groundwater levels, etc.), which take longer to develop and last longer. This index responds more slowly to changing conditions than the Palmer Drought Index. • The Standardized Precipitation Index considers only precipitation. A value of zero indicates the median precipitation amount; the index is negative for drought and positive for wet conditions.
The Standardized Precipitation Index is computed for time scales ranging from 1 month to 24 months.
Maps of these indices show drought at a given point in time and are not necessarily indicators of the Planning Area’s long-term susceptibility to drought (U.S. Drought Monitor, 2025) (NOAA, 2025).
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Drought 6-5
Warning Time
Droughts are climatic patterns that occur over long periods of time. Only generalized warning can take place due to the numerous variables that scientists have not pieced together well enough to make accurate and precise predictions.
Empirical studies conducted over the past century have shown that meteorological drought is never the result of a single cause. It is the result of many causes, often synergistic in nature; these include global weather patterns that produce persistent, upper-level high-pressure systems along the West Coast with warm, dry air resulting in less precipitation.
At this time, scientists do not know how to predict drought more than a month in advance for most locations. Predicting drought depends on the ability to forecast precipitation and temperature.
Anomalies of precipitation and temperature may last from several months to several decades The El Niño-Southern Oscillation—a periodic shifting of ocean atmosphere conditions in the tropical Pacific that ranges from El Niño (warm phase) to neutral to La Niña (cold phase)—offers only limited predictive capability for precipitation in California. La Niña conditions tend to favor a drier outlook for Southern California. Seasonal precipitation forecasting is an important drought response tool and a research area requiring focused investment to develop the predictive ability needed to support water management. Dry conditions become a drought when the impacts of prolonged dry conditions create problems (California Governor's Office of Emergency Services, 2024).
Worst-Case Scenario
An extreme multi-year drought can impact the region with little warning. Combinations of low precipitation and unusually high temperatures could occur over several consecutive years. Intensified by such conditions, extreme wildfires could break out throughout Los Angeles County, as seen in 2025 with the Palisades and Eaton Fires, increasing the need for water. Surrounding communities, also in drought conditions, could increase their demand for water supplies relied upon in the Peninsula, causing social and political conflicts. If such conditions persisted for several years, the economy of Los Angeles County and the Palos Verdes Peninsula could experience setbacks, especially in water dependent industries.
6.1.4 Previous Occurrences
The following sections provide a review of previous drought occurrences in Los Angeles County.
Declarations
Federal Declarations
There have been no federal declarations for drought for Los Angeles County (FEMA, 2025).
State Proclamations
In 1976, 2014, and 2015, California proclaimed drought disasters for Los Angeles County, but no proclamations have been made in the past 5 years since the last mitigation plan updates for Palos Verdes Peninsula communities (Cal OES, 2025).
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USDA Declarations
Between 2019 and 2025, the USDA declared that Los Angeles County experienced seven disasters relating to drought.
Table 6-1. USDA Drought Disaster Declarations
Designation Number Event Begin Date Description
S4647 10/1/2019 Drought-Fast Track
S4916 10/1/2020 Drought-Fast Track
S4945 4/20/2021 Drought-Fast Track
S4979 4/6/2021 Drought-Fast Track
S5146 10/1/2021 Drought-Fast Track
S5371 10/1/2022 Drought-Fast Track
S5943 10/1/2024 Drought-Fast Track
Source: (U.S. Department of Agriculture, 2025)
Summary of Significant Events
Drought is an ongoing hazard that has shaped California’s history. In the mid-1800s, the Great Drought contributed to the demise of the cattle rancho system. In the 1920s and 1930s, dry conditions were prevalent in California and throughout the nation during the Great Depression and Dust Bowl. Later in the 20th century, significant droughts impacting water supplies occurred in the mid-1970s and mid- to early1990s. Recent multi-year droughts occurred in 2007 to 2009, 2012 to 2016, and 2020 to early 2023. At the time of writing, the two watersheds encompassing the Peninsula, San Gabriel Watershed and Santa Monica Bay Watershed are not experiencing drought conditions.
Recent Events
Recent drought periods are described as follows:
• 2020 to 2023 Drought – A new record was set during this multi-year drought, with 2022 becoming the driest year in California since official drought records began in 1895. All 58 counties in California were impacted as USDA disaster-designated areas. This included residents in Los Angeles County.
• 2012 to 2016 Drought - The driest 3 consecutive years for statewide precipitation were between 2012 to 2014. Calendar year 2013 set minimum annual precipitation records for many communities.
• 2007 to 2009 Drought—This was California’s first statewide proclamation of drought emergency, and the first drought in more than 70 years where water shortage was directly linked to social services impacts (California Department of Water Resources, 2010). Several California counties were also included in a state disaster proclamation, but Los Angeles County was only included in the emergency proclamation.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Drought 6-7
Source: (National Intigrated Drought Information System, 2026) Figure 6-2. Percent of Los Angeles County Affected by Drought Conditions 2000 to January 2026
6.1.5 Future Conditions
Future hazard conditions, including frequency and severity of future events, are discussed in the sections below.
Probability
Drought has a high probability of occurrence in Los Angeles County, including the Palos Verdes Peninsula. From January 2000 to December 2025, some part of Los Angeles County experienced a USDM rating of D0 or higher in 899 out of 1,360 weeks—two-thirds of the weeks. The Planning Area has also been included in USDA drought disaster declarations in 5 of the last 7 years. Historical drought data for the Planning Area indicate there have been four significant multi-year droughts in the last 38 years (1987 to 2025), amounting to a severe drought every 9 years on average.
Climate Change
Future impacts of climate change are expected to influence future drought occurrences for the Planning Area.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Drought 6-8
With a warmer climate, droughts could become more frequent, more severe, and longer lasting. The Fourth National Climate Assessment Report for the United States indicates that “rising air and water temperatures and changes in precipitation are intensifying droughts. Changes in the relative amounts and timing of snow and rainfall are leading to mismatches between water availability and needs in some regions. Groundwater depletion is exacerbating drought risk.” (USGCRP, 2018).
Because changes in precipitation patterns are still uncertain, the potential impacts and likelihood of drought are uncertain. Department of Water Resources (DWR) has noted impacts of climate change on statewide water resources by charting changes in snowpack, sea level, and river flow. As temperatures rise and more precipitation comes in the form of rain instead of snow, these changes will likely continue or grow even more significant. DWR estimates that parts of the state will experience a 48 to 65 percent loss in snowpack by the end of the century compared to historical averages (DWR, 2021). Increasing temperatures may also increase net evaporation from reservoirs. The Planning Area’s water supply is derived from groundwater.
Potential Future Impacts
Even though the population of the Palos Verdes Peninsula is expected to continue slowly declining, its location in California’s most populous County exposes it to significant risk of heightened water consumption and devastating drought consequences. Even modest population growth or shifts in development patterns can place significant strain on the Planning Area’s limited water resources.
Additionally, any increase in development, particularly in wildland-urban interface areas, can elevate both water demand and wildfire risk. These changes may lead to water shortages, reduced water quality, and heightened public health risks, especially for vulnerable populations. A growing population could complicate emergency response efforts during drought-related events like wildfires, which are intensified by prolonged dry conditions. Economic impacts may also arise, including reduced tourism and increased utility costs, all of which could further challenge the Planning Area’s resilience to future droughts.
6.2 VULNERABILITY ASSESSMENT
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(ii) The plan must include a description of the jurisdiction’s vulnerability to the hazards of concern and include an overall summary of the hazard’s impact on the community. The impacts need to include the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the hazard areas, and estimate of potential dollar losses to vulnerable structures, and a description of land uses and development trends.
6.2.1 Summary of Vulnerability
The entire Planning Area is exposed to the drought hazard, with the potential to affect the entire population.
Drought can affect a wide range of economic, environmental, and social activities. Its impacts can span many sectors of the economy because water is integral to the ability to produce goods and provide services. The impacts can reach well beyond the area undergoing physical drought. Vulnerability of an activity to drought depends on its water demand and the water supplies available to meet the demand.
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6.2.2 Impact on Life, Health, and Safety
Drought can affect people’s health and safety, including health problems related to low water flows, poor water quality, or dust and pollution (National Drought Mitigation Center, 2025). Other possible impacts include recreational risks; effects on air quality; diminished living conditions related to energy, air quality, and hygiene; compromised food and nutrition; and increased incidence of illness and disease (U.S.
Centers for Disease Control and Prevention, 2024). Droughts can also lead to reduced local firefighting capabilities.
The entire population of the Palos Verdes Peninsula is vulnerable to droughts.
Equity Priority Communities
In addition to water scarcity, drought conditions can also lead to power outages. Reduced water availability can limit hydroelectric power generation, while extreme heat and wildfire threats can strain the electrical grid or necessitate public safety power shutoffs. These outages can severely impact individuals with disabilities, older adults, and those with access and functional needs who rely on powered medical devices, refrigerated medications, or climate control for health and safety.
6.2.3 Impact on General Building Stock
The general building stock will not be directly affected by drought conditions. Droughts can have significant impacts on landscapes, which could cause a financial burden to property owners. However, these impacts are not considered critical in planning for impacts from the drought hazard.
6.2.4 Impact on Community Lifelines
While community lifelines as defined for this plan will continue to be operational during a drought, instances of drought can put a significant amount of strain on water utilities services. This, in addition to a drought’s ability to naturally worsen wildfires through cascading effects, can impede firefighting capabilities for both wildfires and smaller house fires (NOAA NIDIS, 2025).
Beyond fires, the cost of potable water may increase, but the community lifeline that includes hydration will still function. Landscaping at community lifeline facilities may not be maintained because of limited resources, but the risk to those areas will be largely aesthetic. For example, when water conservation measures are in place, landscaped areas may not be watered frequently and may die. These aesthetic impacts are not considered significant.
6.2.5 Impact on the Economy
A prolonged drought can have a serious economic impact for all communities. As drought conditions persist, the availability of water for both residential and business use becomes increasingly limited. Local and state agencies may impose water restrictions. These restrictions may include placing limitations on watering lawns, car washing services, or any other recreational/commercial outdoor use of water supplies. Cost of accessing and transporting water may rise, placing further strain on household budgets and business operations. Industries that rely on water, such as nurseries, landscaping services, and tourism, may experience reduced demand or be forced to scale back.
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6.2.6 Impact on Historic and Cultural Resources
The increase in wildfire risk due to drought would be the primary impact on historic and cultural assets.
6.2.7 Impact on Ecosystems and Natural Resources
Drought increases wildfire risk, and wildfires in turn increase demand for water. Prolonged periods of drought can result in detrimental changes in the vegetative structure, weakening trees which are more vulnerable to wildfire or insect outbreaks (EPA, 2025). The loss of trees due to distressed health, pests, or fire can produce increased risk of other hazards due to reduced ability to retain runoff during heavy rainfall events (Hoegh-Guldberg, et al., 2018).
The impact to ecosystems, even in suburban areas, can be profound during a drought. Surface water and waterways are reduced or dry up completely which impacts the habitat for surrounding flora and fauna reliant on those resources.
6.2.8 Change in Vulnerability Since the Prior Planning Area HMPs The Planning Area’s vulnerability to drought may have increased because of prolonged dry periods and climate variability, not because of population or development. The Palos Verdes Peninsula’s population has declined since the prior Planning Area HMPs. Los Angeles County’s reliance on limited water resources, however, continues to make it sensitive to drought conditions.
6.3 MITIGATION OPPORTUNITIES
Table 6-2 presents a range of potential opportunities considered by the Planning Partnership for mitigating the drought hazard.
Table 6-2. Potential Opportunities to Mitigate the Drought Hazard Community Scale Organizational Scale Government Scale
Manipulate the Hazard
• None • None • Stormwater management
• Identify alternative water sources
Reduce Exposure and Vulnerability
• Drought-resistant
landscapes
• Reduce water system
losses
• Modify plumbing
systems (through water
saving kits)
• Drought-resistant
landscapes
• Reduce private water
system losses
• Water use conflict regulations
• Reduce water system losses
• Distribute water saving kits
• Implement/expand water reuse projects
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Community Scale Organizational Scale Government Scale
Build Local Capacity
• Practice active water
conservation
• Practice active water
conservation
• Public education on drought resistance
• Develop or expand recycled water network
• Identify alternative water supplies for
times of drought; mutual aid agreements
with alternative suppliers
• Develop drought contingency plan
• Develop criteria “triggers” for droughtrelated actions • Improve accuracy of water supply
forecasts
• Modify rate structure to influence active
water conservation techniques
• Increase emergency storage capacity
Nature-based Opportunities
• Promote and use reclaimed water supplies
• Increase capacity for stored surface water to create habitats and ecosystems for aquatic species • Promote and use active groundwater recharge
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Earthquake 7-1
7. EARTHQUAKE
7.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.
7.1.1 Description of the Hazard
Defining the Hazard
An earthquake is the vibration of the earth’s surface following a release of energy in the earth’s crust.
This energy can be generated by a sudden dislocation of the crust or by a volcanic eruption. Most destructive quakes are caused by dislocations of the crust. The crust may first bend and then, when the stress exceeds the strength of the rocks, break and snap to a new position. In the process of breaking, vibrations called “seismic waves” are generated. These waves travel outward from the source of the earthquake at varying speeds.
The location of an earthquake is commonly described by its focal depth and the geographic position of its epicenter. The focal depth of an earthquake is the depth from the Earth’s surface to the region where an earthquake’s energy originates (the focus or hypocenter). The epicenter of an earthquake is the point on the Earth’s surface directly above the hypocenter.
Cause of the Hazard
In California, the Pacific and North American plates slide past each other in opposing directions at a rate of about 1.5 inches per year. Friction between the plates can cause sections to stick. When they break free sudden movements, the movements release energy that travels through the ground as waves, causing shaking at the surface in the form of earthquakes (California Governor's Office of Emergency Services, 2024).
Tectonic Plates
The Earth’s crust, which is the rigid outermost shell of the planet, is broken into seven or eight major tectonic plates (depending on how they are defined) and many minor plates. Where the plates meet, they move in one of three ways along their mutual boundary: convergent (two plates moving together), divergent (two plates moving apart), or transform (two plates moving parallel to one another).
Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. Subduction is a geological process that takes place at convergent boundaries of tectonic plate, in which one plate moves under another. Regions where this process occurs are known as subduction zones, and they have the potential to generate highly damaging earthquakes.
California is seismically active because of movement of the North American Plate, east of the San Andreas Fault, and the Pacific Plate to the west, which includes the state’s coastal communities. The
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transform (parallel) movement of these tectonic plates against one another creates stresses that build as the rocks are gradually deformed. The rock deformation, or strain, is stored in the rocks as elastic strain energy. When the strength of the rock is exceeded, rupture occurs along a fault. The rocks on opposite sides of the fault slide past each other as they spring back into a relaxed position. The strain energy is released partly as heat and partly as elastic waves called seismic waves. The passage of these seismic waves produces the ground shaking in earthquakes.
Seismic Fault Lines
Geologists have found that earthquakes reoccur along faults, which are zones of weakness in the earth’s crust. When a fault experiences an earthquake, there is no guarantee that all the stress has been relieved.
Another earthquake can still occur. In fact, relieving stress along one part of a fault may increase it in another part.
Faults are more likely to have future earthquakes on them if they have more rapid rates of movement, have had recent earthquakes along them, experience greater total displacements, and are aligned so that movement can relieve the accumulating tectonic stresses. Geologists classify faults by their relative hazards. “Active” faults, which represent the highest hazard, are those that have ruptured to the ground surface during the Holocene period (about the last 11,000 years). “Potentially active” faults are those that have moved in the past 1.6 million years (USGS, 2025).
Determining if a fault is “active” or “potentially active” depends on geologic evidence, which may not be available for every fault. The majority of the seismic hazards are on well-known active faults. However, inactive faults, where no displacements have been recorded, also have the potential to reactivate or experience displacement along a branch sometime in the future. An example of a fault zone that has been reactivated is the Foothills Fault Zone. The zone was considered inactive until evidence of an earthquake (approximately 1.6 million years ago) was found near Spenceville, California. Then, in 1975, an earthquake occurred on another branch of the zone near Oroville, California (now known as the Cleveland Hills Fault). The State Division of Mines and Geology indicates that increased earthquake activity throughout California may cause tectonic movement along currently inactive fault systems.
Summary of Potential Impacts
According to the USGS Earthquake Hazards Program, an earthquake hazard is anything associated with an earthquake that may affect people’s normal activities. This includes the following:
• Surface Faulting—Displacement that reaches the earth’s surface during slip along a fault.
Commonly occurs with shallow earthquakes, those with an epicenter less than 20 kilometers. • Ground Motion (shaking)—The movement of the earth’s surface from earthquakes or explosions.
Ground motion or shaking is produced by waves that are generated by sudden slip on a fault or sudden pressure at the explosive source and travel through the earth and along its surface. • Landslide—A movement of surface material down a slope. • Liquefaction—A process by which water‐saturated sediment temporarily loses strength and acts as a fluid. Earthquake shaking can cause this effect.
• Tectonic Deformation—A change in the original shape of a material due to strain.
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Earthquakes can directly cause buildings and bridges to collapse; disrupt utility services; and trigger landslides, avalanches, flash floods, fires, and tsunamis. Infrastructure collapses during earthquakes produced eight of California’s 10 costliest disasters in the last 100 years (California Governor's Office of Emergency Services, 2024).
Cascading Hazard Impacts
Cascading impacts result when one hazard event triggers one or more other hazard events that may still trigger others. The following cascading impacts associated with earthquakes are relevant to the Planning Area (California Governor's Office of Emergency Services, 2024):
• Surface Fault Rupture—When a fault rupture extends to the earth’s surface, the displacement can catastrophically damage structures or utilities. Fissuring, settlement, and permanent horizontal and vertical ground shifting often accompany large earthquakes. Such displacement can significantly increase damage.
• Fires—Fires following earthquakes may result from multiple causes, including overturned burning candles, sparking from downed power lines, and broken gas pipelines. Additionally, fire departments may be severely stained after earthquakes. Impaired communications, water supply, transportation, and other resources affect fire department response. Several computer programs, such as Hazus, URAMP, SERA, and RiskLink provide ways to assess the fire-following-earthquake vulnerability of a community in future earthquakes.
• Liquefaction—Ground settlement during liquefaction can cause damage when the settlement varies significantly across the length of a structure. Liquefaction can occur in susceptible soils such as NEHRP Types D, E, and F. This can severely damage structures and infrastructure. • Landslides—Landslides caused by earthquakes can be widespread over the immediate area and at greater distances where hillsides are susceptible. These landslides can significantly damage structures and transportation and utility lifelines.
• Power Outages—Earthquakes of all magnitudes can damage power lines and electrical facilities, impacting community lifelines that rely on power.
• Hazardous Materials Release—Earthquakes can lead to the release of hazardous materials from collapsed buildings and severed pipelines. This may include chemical accidents, oil spills, the release of gases, and runoff of hazardous materials.
7.1.2 Location
Faults
The greatest earthquake threat in the United States is along tectonic plate boundaries and seismic fault lines located in the western states, including California. Figure 7-1 shows relative seismic risk for the United States.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Earthquake 7-4
Source: (USGS, 2018)
Figure 7-1. USGS National Seismic Hazard Map
A direct relationship exists between a fault’s length and location and its ability to generate damaging ground motion at a given site. Small, local faults produce lower magnitude quakes, but ground shaking can be strong, and damage can be significant in areas close to the fault. Large regional faults can generate earthquakes of great magnitudes but, because of their distance and depth, they may result in only moderate shaking in an area. The Palos Verdes Peninsula is in a region of High seismicity. According to the USGS, Southern California has the highest level of earthquake risk in the United States, with half of the expected financial losses from earthquakes in the Nation expected to occur in Southern California.
Sitting astride the Pacific-North American plate boundary at the Big Bend of the San Andreas Fault, Southern California has over 300 faults capable of producing magnitude 6.0 and larger earthquakes.
Affecting the more than 20 million inhabitants of the Los Angeles and San Diego metropolitan areas, this complex set of faults presents the greatest urban risk in the United States. Figure 7-2 shows the known faults within close proximity to the Planning Area.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Earthquake 7-5
Source: (California Geological Survey, 2015)
Figure 7-2. Fault Activity Map
National Earthquake Hazards Reduction Program Soils
National Earthquake Hazards Reduction Program (NEHRP) soil types define locations that will be significantly impacted by an earthquake. NEHRP Soils B and C typically can sustain low-magnitude ground shaking without much effect. Areas with NEHRP Soils D, E, and F are most commonly affected by ground shaking. NEHRP soils are described as follows:
• Site Class A: Hard rock
• Site Class B: Rock
• Site Class C: Very dense soil and soft rock
• Site Class D: Stiff soil
• Site Class E: Soft soil
• Site Class F: Soils requiring site-specific evaluation, like liquefiable soils, peat, or thick soft clays.
Figure 7-3 shows that NEHRP soil classifications within the Planning Area include C and D soils.
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Figure 7-3. Palos Verdes Peninsula NEHRP Seismic Site Class
7.1.3 Extent
Measuring Intensity
Earthquakes are typically classified in one of two ways: By the amount of energy released, measured as magnitude; or by the impact on people and structures, measured as intensity.
Magnitude
An earthquake’s magnitude is a measure of the energy released at the source of the earthquake.
Magnitude is commonly expressed by ratings on the moment magnitude scale (Mw), the most common scale used today (USGS n.d.). This scale is based on the total moment release of the earthquake (the product of the distance a fault moved, and the force required to move it). The scale is as follows:
Great—Mw > 8
Major—Mw = 7.0 – 7.9
Strong—Mw = 6.0 – 6.9
Moderate—Mw = 5.0 – 5.9
Light—Mw = 4.0 – 4.9
Minor—Mw = 3.0 – 3.9
Micro—w < 3
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Intensity
An earthquake’s intensity is a measure of how strong an earthquake feels at any one location. It can vary widely across the range where an earthquake is experienced. The modified Mercalli intensity scale is most commonly used. The modified Mercalli intensity scale is generally represented visually using USGS ShakeMaps, which show the expected ground shaking produced by an earthquake with a specified magnitude and epicenter. An earthquake has only one magnitude and one epicenter, but it produces a range of ground shaking at sites throughout the region, depending on the distance from the earthquake, the rock and soil conditions at sites, and variations in the propagation of seismic waves from the earthquake due to complexities in the structure of the earth’s crust (California Governor's Office of Emergency Services, 2024).
Table 7-1. Mercalli Scale and Peak Ground Acceleration Comparison Modified
Mercalli Scale Perceived Shaking
Potential Structure Damage
Estimated PGA a
Resident Buildings (%)
Vulnerable
Buildings
I Not felt None None <0.17%
II Weak None None 0.17%-1.4%
IV Light None None 1.4%-3.9%
V Moderate Very Light Light 3.9%-9.2%
VI Strong Light Moderate 9.2%-18%
VII Very Strong Moderate Moderate/Heavy 18%-34%
VIII Severe Moderate/Heavy Heavy 34%-65%
IX Violent Heavy Very Heavy 65%-124%
X-XII Extreme Very Heavy Very Heavy >124%
a PGA measure in percent of g, where g is the acceleration of gravity Source: (USGS, 2011) (USGS, 2025)
Ground Motion
Earthquake hazard assessment is based on expected ground motion. During an earthquake when the ground is shaking, it also experiences acceleration. The peak acceleration is the largest increase in velocity recorded by a particular station during an earthquake. Estimates are developed of the annual probability that certain ground motion accelerations will be exceeded; the annual probabilities can then be summed over a time period of interest.
The most commonly mapped ground motion parameters are horizontal and vertical peak ground accelerations (PGA) for a given soil type. PGA is a measure of how hard the earth shakes, or accelerates, in a given geographic area. Instruments called accelerographs record levels of ground motion due to earthquakes at stations throughout a region. PGA is measured in g (the acceleration due to gravity) or expressed as a percent acceleration force of gravity (%g). These readings are recorded by state and federal agencies that monitor and predict seismic activity.
Maps of PGA values form the basis of seismic zone maps that are included in building codes such as the International Building Code. Building codes that include seismic provisions specify the horizontal
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force due to lateral acceleration that a building should be able to withstand during an earthquake. PGA values are directly related to these lateral forces that could damage “short period structures” (e.g., singlefamily dwellings). Longer period response components determine the lateral forces that damage larger structures with longer natural periods (apartment buildings, factories, high-rises, bridges).
ShakeMaps
The USGS Earthquake Hazards Program produces maps called ShakeMaps that map ground motion and shaking intensity following significant earthquakes. ShakeMaps focus on the ground shaking caused by the earthquake, rather than on characteristics of the earthquake source, such as magnitude and epicenter. An earthquake has only one magnitude and one epicenter, but it produces a range of ground shaking at sites throughout the region, depending on the distance from the earthquake, the rock and soil conditions at sites, and variations in the propagation of seismic waves from the earthquake due to complexities in the structure of the earth’s crust.
A ShakeMap shows the extent and variation of ground shaking immediately across the surrounding region following significant earthquakes. Such mapping is derived from peak ground motion amplitudes recorded on seismic sensors, with interpolation where data are lacking based on estimated amplitudes.
Color-coded instrumental intensity maps are derived from empirical relations between peak ground motions and Modified Mercalli intensity. In addition to the maps of recorded events, the USGS creates the following:
• Scenario ShakeMaps of hypothetical earthquakes of an assumed magnitude on known faults. • Probabilistic ShakeMaps, based on predicted shaking from all possible earthquakes over a 10,000-year period. In a probabilistic map, information from millions of scenario maps is combined to make a forecast for the future. The maps indicate the ground motion at any given point that has a given probability of being exceeded in a given timeframe, such as a 100-year (1 percent annual chance) event.
The earthquake scenarios modeled for the risk assessment are shown on the following figures:
• Figure 7-5. Compton M7.45 Scenario
• Figure 7-6. Palos Verdes M7.38 Scenario
• Figure 7-7. Redondo Canyon M6.65 Scenario
National Seismic Hazard Map
National maps of earthquake shaking hazards provide information for creating and updating seismic design requirements for building codes, insurance rate structures, earthquake loss studies, retrofit priorities and land use planning. After thorough review of the studies, professional organizations of engineers update the seismic-risk maps and seismic design requirements contained in building codes (Brown, et al., 2001). The USGS updated the National Seismic Hazard Maps in 2018. New seismic, geologic, and geodetic information on earthquake rates and associated ground shaking were incorporated into these revised maps (Figure 7-1).
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Liquefaction and Soil Types
Soil liquefaction occurs when water-saturated sands, silts or gravelly soils are shaken so violently that the individual grains lose contact with one another and float freely in the water, turning the ground into a pudding-like liquid. Building and road foundations lose load-bearing strength and may sink into the ground.
The NEHRP creates maps based on soil characteristics to help identify locations subject to liquefaction.
NEHRP soil types define the locations that will be significantly impacted by an earthquake. Table 7-2 summarizes NEHRP soil classifications. NEHRP Soils B and C typically can sustain ground shaking without much effect, dependent on the earthquake magnitude. The areas that are commonly most affected by ground shaking have NEHRP Soils D, E, and F. In general, these areas are also most susceptible to liquefaction. Figure 7-4 shows liquefaction susceptibility in the Planning Area.
Table 7-2. NEHRP Soil Classification System
NEHRP Soil
Type Description
Mean Shear Velocity
to 30 m (m/s)
A Hard Rock 1,500
B Firm to Hard Rock 760-1,500
C Dense Soil/Soft Rock 360-760
D Stiff Soil 180-360
E Soft Clays <180
F Special Study Soils (liquefiable soils, sensitive clays, organic soils, soft clays > 36 m thick)
-
Warning Time
There is no current reliable way to predict the day or month that an earthquake will occur at any given location. Researchers are studying potential earthquake warning systems to give notice before damaging earthquake events. The warning time could allow someone to take preventative measures such as to get under a desk, step away from a hazardous material, or shut down a computer system (California Governor's Office of Emergency Services, 2024).
Cal OES’s Earthquake Early Warning California (MyShake), developed in partnership with UC Berkeley and USGS ShakeAlert, is a statewide, publicly available warning system that provides seconds or tens of seconds to take cover before shaking occurs, depending on the location of the event. The system uses data from motion sensors and Global Navigation Satellite System to detect earthquakes and notify Californians of an earthquake in advance. Individuals can download the MyShake App on their mobile devices for earthquake warnings (California Governor's Office of Emergency Services, 2024).
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Figure 7-4. Palos Verdes Peninsula Liquefaction Susceptibility
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Figure 7-5. Compton M7.45 Scenario
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Figure 7-6. Palos Verdes M7.38 Scenario
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Figure 7-7. Redondo Canyon M6.65 Scenario
Worst-Case Scenario
With the abundance of fault exposure in southern California, the potential scenarios for earthquake activity are many. Any earthquake above a magnitude of 5.0 or greater on faults near the Planning Area would result in significant structural damage, particularly to older, unreinforced masonry buildings and infrastructure not built to modern seismic standards. Followed by earthquakes, secondary hazards such as severe landslides could worsen the situation. Ground shaking could trigger slope failures, blocking transportation and isolating neighborhoods. In dry and peak wildfire conditions, the combination of damaged infrastructure and power lines along with dry vegetation could ignite wildfires.
Potential warning systems could give approximately 40 seconds notice that a major earthquake is about to occur but would not provide enough warning other than to duck, cover and hold on for personal safety.
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7.1.4 Previous Occurrences
The following sections provide a review of previous earthquake occurrences in Los Angeles County.
Declarations
Federal Declarations
Past federal disaster declarations for earthquakes in Los Angeles County have included the 1994 Northridge Earthquake (DR-1008), the 1987 Whittier Narrows Earthquake (DR-799), and the 1971 San Fernando Earthquake (DR-299, but no declarations have been made in the past 5 years since the last mitigation plan updates for Palos Verdes Peninsula communities (FEMA, 2025).
State Proclamations
In the past 5 years, California has not declared disasters related to earthquakes in Los Angeles County (Cal OES, 2025).
USDA Declarations
Between 2019 and 2025, the USDA has not declared disasters related to earthquakes in Los Angeles County (U.S. Department of Agriculture, 2025).
Summary of Significant Events
2024 Earthquake Near Highland Park
An unnamed 4.4 magnitude earthquake along the Puente Hills fault shook the greater Los Angeles area on August 12, 2024. Community members reportedly felt the quake as far north as Porterville and south to Chula Vista.
2010 Pico Rivera Earthquake
Pico Rivera was the epicenter of a magnitude 4.4 earthquake on March 16, 2010. The earthquake struck about 1.5 miles northeast of Pico Rivera at a depth of 11.7 miles, which is considered shallow. The USGS stated that the quake was likely from the Puente Hills’ thrust fault. The epicenter was about 4.5 miles south of the epicenter of the 1987 Whittier Narrows earthquake. Both earthquakes exhibited thrust faulting. However, the 2010 earthquake strike rotated clockwise, suggesting that a different thrust system was activated. There were no injuries or major damage, but plenty of people felt the shaking. It was reported to have been felt from San Bernardino County to Santa Monica, and as far south as San Diego.
1994 Northridge Earthquake
The 1994 Northridge Earthquake was the costliest seismic event in California since the 1906 San Francisco Earthquake. The infrastructure of the metropolitan area was severely disrupted. Freeways collapsed, power systems for the city and linked communities as far away as Oregon were temporarily blacked out, and communications were disrupted. The California State HMP reports the Northridge Earthquake caused over $40 billion of disaster losses, 57 deaths, and 11,846 injuries (Cal OES, 2018).
Officially lasting approximately 30 seconds, and with a magnitude of 6.7, this earthquake caused significant damage to buildings. Of 57 fatalities attributed to this quake, 16 were a result of the collapse
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Earthquake 7-9
of a single structure—the Northridge Meadows apartment building. The ground motion was measured throughout Southern California, including intensity readings of 1.82 g near the Ventura Freeway in the Tarzana area. Ground motions as strong as 1.21 g were measured as far away as Inglewood (approximately 25 miles from Northridge). One “g” of ground motion is enough to make unsecured buildings move off their foundations.
According to the USGS and the Southern California Earthquake Center, the Northridge Earthquake raised nearby mountains by as much as 70 centimeters. The fault, which was previously unknown, appears to be truncated by the fault that broke in the similarly sized 1971 San Fernando Earthquake, the two faults abutting at a depth of 5 miles. The Northridge Earthquake caused many times more damage than the 1971 event, primarily because its fault is directly under the densely populated valley, whereas the 1971 fault lies under the mountains.
The 1971 San Fernando Earthquake
The 1971 San Fernando earthquake (also known as the 1971 Sylmar earthquake) occurred in the early morning of February 9 in the foothills of the San Gabriel Mountains in Southern California. The origin of faulting was located 5 miles north of the San Fernando Valley. The unanticipated thrust earthquake had a magnitude of 6.5 on the Ms scale and 6.6 on the Mw scale, and a maximum Mercalli intensity of XI.
Damage was locally severe in the northern San Fernando Valley and surface faulting was extensive to the south of the epicenter in the mountains, as well as urban settings along city streets and neighborhoods. Uplift and other effects affected private homes and businesses. The shaking surpassed building code requirements and exceeded what engineers had prepared for, and although most dwellings in the valley had been built in the prior two decades, even modern earthquake-resistant structures sustained serious damage.
Recent Events
According to the USGS Search Earthquake Catalog, there have been no earthquakes in the Palos Verdes Peninsula in the 4.5+ Richter magnitude since January 2019. Earthquakes near the vicinity of the Palos Verdes Peninsula in the 2.5 – 4.5 Richter magnitude since January 2019 are listed in Table 7-3. None of these events resulted in notable impacts to the Planning Area. Locations of recent events are shown on Figure 7-8.
Table 7-3. USGS Earthquake Reports
Incident Period Magnitude Location
May 4, 2019 M 2.6 7 km WSW of Hermosa Beach
May 5, 2019 M 2.5 5 km WSW of Hermosa Beach
December 24, 2019 M 2.7 16 km S of Rancho Palos Verdes
December 24, 2019 M 2.7 16 km S of Rancho Palos Verdes
February 13, 2021 M 2.6 17km S of San Pedro
May 4, 2021 M 2.6 7km WSW of Hermosa Beach
May 9, 2021 M 2.5 - 3.5 5km WSW of Hermosa Beach
June 18, 2021 M 2.8 4 km WSW of Hermosa Beach
September 18, 2021 M 2.8 Carson, CA
September 24, 2021 M 2.6 Carson, CA
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Incident Period Magnitude Location
January 11, 2022 M 2.8 Carson, CA
January 11, 2022 M 2.5 Carson, CA
October 12, 2022 M 2.5 Carson, CA
November 5, 2022 M 2.7; Carson, CA
June 8, 2023 M 2.5 Carson, CA
August 25, 2023 M 2.7 Carson, CA
January 1, 2024 M 4.1 18 km S of Rancho Palos Verdes
April 17, 2024 M 2.6 13 km S of Rancho Palos Verdes
July 21, 2024 M 3.6 8km WNW of Palos Verdes Estates
September 2, 2024 M 3.1 22 km W of Rancho Palos Verdes; September 7, 2024 M 2.8 – 3.2 22 km W of Rancho Palos Verdes April 26, 2025 M 2.7 7 km W of Seal Beach
July 4, 2025 M2.5 9 km SSE of San Pedro
Source: (USGS, 2025)
Source: (USGS, 2025)
Figure 7-8. USGS Earthquake Catalog 2019 – 2025
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7.1.5 Future Conditions
Future hazard conditions, including frequency and severity of future events, are discussed in the sections following.
Probability
California experiences hundreds of earthquakes each year, most with magnitudes below 3.0 and minimal damage. Earthquakes that cause moderate damage to structures occur several times a year. According to the USGS, a strong earthquake measuring greater than Magnitude 5.0 occurs statewide every 2 to 3 years, and major earthquakes of more than Magnitude 7.0 occur once a decade. The San Andreas Fault has the potential for experiencing major to great events.
Based on the most recent earthquake forecast model for California, scientists estimate that in the next 30 years the Los Angeles region has a 60 percent probability of an earthquake of Magnitude 6.7 or greater, a 46 percent probability of an earthquake of Magnitude 7 or greater, and a 31 percent probability of an earthquake of Magnitude 7.5 (USGS, 2025).
Fault rupture is the sliding movement of rock on either side of a fault. This phenomenon is responsible for causing the resulting shaking. The Third Uniform California Earthquake Rupture Forecast (UCERF3) is a comprehensive model of earthquake occurrence for California. It represents the best available science for authoritative estimates of the magnitude, location, and likelihood of potentially damaging earthquakes (SCEC, 2023). The UCERF3 predicts the probability of an earthquake of Magnitude 6.7 or greater over the next 30 years as shown on Figure 7-9. The UCERF3 also defined the following estimated 30-year probability for the deterministic earthquake scenarios used for the risk assessment in this LHMP:
• Compton M7.45 Scenario = 0.26 percent estimate 30-year probability • Palos Verdes M7.38 Scenario = 2.73 percent estimate 30-year probability • Redondo Canyon M6.65 Scenario = 0.20 percent estimate 30-year probability
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Source: (Southern California Earthquake Center, 2025)
Figure 7-9. UCERF3 Earthquake Probability
Climate Change
It is unknown whether climate change has a direct impact on earthquake probability or severity. However, cascading hazards related to earthquakes are exacerbated by climate change. Increasing air temperatures and extreme weather events can affect soil integrity and affect erosion, sedimentation, and landslide occurrence associated with earthquakes.
Potential Future Impacts
Since all of the Planning Area is located within earthquake hazard zones, all future development will, to some extent, be exposed to the earthquake hazard. The municipal Planning Partners will strictly enforce all seismic building codes and design standards to prevent loss of life and property from earthquakes.
Public education, cooperation with the development community, and individual preparedness are essential.
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7.2 VULNERABILITY ASSESSMENT
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(ii) The plan must include a description of the jurisdiction’s vulnerability to the hazards of concern and include an overall summary of the hazard’s impact on the community. The impacts need to include the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the hazard areas, and estimate of potential dollar losses to vulnerable structures, and a description of land uses and development trends.
7.2.1 Summary of Vulnerability
The entire Planning Area is exposed to the earthquake hazard, so an earthquake has the potential to affect the entire population, and all buildings in the Planning Area, all of the Planning Area’s identified critical facilities, and the entire environment of the Planning Area.
7.2.2 Impact on Life, Health, and Safety
Depending on the severity of the earthquake some people may be directly injured or killed. In addition, homes and businesses may be damaged, resources and supplies may be scarce, business interruptions may keep people from working, utilities may have outages, schools may be temporarily closed, and road closures may cause extra time and travel. All of these indirect effects could impact people who suffered no direct harm from the earthquake. Thus, the entire population must deal with the consequences of earthquakes to some degree.
Impacts on persons and households in the Planning Area were estimated for the scenario events assessed through the Level 2 Hazus analysis. Table 7-4 summarizes the results.
Table 7-4. Estimated Earthquake Impact on Persons and Households City
Compton M7.45 Palos Verdes M7.38
Redondo Canyon
M6.65
Displaced HouseholdsShort-Term ShelterDisplaced HouseholdsShort-Term ShelterDisplaced HouseholdsShort-Term Shelter Palos Verdes Estates 51 22 110 47 81 35
Rancho Palos Verdes 364 161 873 386 568 257
Rolling Hills 1 0 2 1 0 0
Rolling Hills Estates 3 1 10 4 8 3
Totals 419 185 995 438 657 296
Equity Priority Communities
While all people in the Planning Area are considered exposed and potentially vulnerable, those who may live in structures that do not conform to seismic building codes; and therefore, sustain more damage during an event, are more vulnerable. Those organizations with physical structures that provide care, services, and shelter may be impacted as a result of an earthquake. Loss of water, power, roads, phones,
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and transportation due to earthquake events can be particularly dangerous for those with certain access and functional needs. Residents who live in neighborhoods with one point of egress may also be more vulnerable if the evacuation route is impacted.
7.2.3 Impact on General Building Stock
Building Age
Table 7-5 identifies significant milestones in building and seismic code requirements that directly affect the structural integrity of development. Using these time periods, the planning team used Hazus to identify the number of structures in the Planning Area by date of construction.
Table 7-5. Age of Structures in the Palos Verdes Peninsula Time Period
Number of Current
Structures Built in
Period Significance of General Time Frame for Building Requirements Pre-1933 66 Before 1933, there were no explicit earthquake requirements in building codes. State law did not require local governments to have building officials or issue building permits.
1933 to 1940 102 In 1940, the first strong motion recording was made. 1941 to 1960 5,127 In 1960, the Structural Engineers Association of California published guidelines on recommended earthquake provisions. 1961 to 1975 11,081 In 1975, significant improvements were made to lateral force requirements.
1976 to 1993 3,973 In 1994, the Uniform Building Code was amended to include provisions for seismic safety.
1994 to Present 2,125 Seismic code is currently enforced.
Total 22,474
The number of structures does not reflect the number of total housing units, as many multi-family units and attached housing units are reported as one structure. About 9 percent of the Planning Area’s structures were constructed after the Uniform Building Code was amended in 1994 to include seismic safety provisions. Less than 1 percent of the structures were built before 1933 when there were no building permits or seismic standards.
Loss Potential
Property losses were estimated through the Level 2 Hazus analysis for the assessed earthquake fault scenarios. Table 7-6 shows the estimates for damage to structures and building contents with the percent of total replacement value. The Hazus analysis also estimated the amount of earthquake-caused debris in the Planning Area for the assessed events, as summarized in Table 7-7.
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Table 7-6. Loss Estimates for Fault Scenarios
City
Estimated Loss Associated with Earthquake % of Total
Replacement
Structure Contents Total Value
Compton M7.45
Palos Verdes Estates $446,647,695 $146,765,435 $593,413,130 10.3% Rancho Palos Verdes $1,043,271,733 $348,773,413 $1,392,045,146 10.8% Rolling Hills $99,677,745 $30,707,295 $130,385,040 12.2% Rolling Hills Estates $468,250,162 $160,116,003 $628,366,164 14.4% Total $2,057,847,334 $686,362,146 2,744,209,480 11.4%
Palos Verdes M7.38
Palos Verdes Estates $538,584,168 $183,729,347 $722,313,516 12.5% Rancho Palos Verdes $1,281,027,168 $437,494,870 $1,718,522,038 13.3% Rolling Hills $112,505,474 $34,967,268 $147,472,741 13.8% Rolling Hills Estates $670,754,311 $230,028,018 $900,782,328 20.6% Total $2,602,871,121 $886,219,503 3,489,090,624 14.5%
Redondo Canyon M6.65
Palos Verdes Estates $531,917,704 $179,507,789 $711,425,492 12.3% Rancho Palos Verdes $1,075,689,302 $361,305,822 $1,436,995,124 11.2% Rolling Hills $94,397,701 $29,210,738 $123,608,439 11.5% Rolling Hills Estates $451,096,021 $156,780,926 $607,876,947 13.9% Total $2,153,100,728 $726,805,274 2,879,906,001 11.9%
Table 7-7. Estimated Earthquake-Caused Debris
City
Debris to Be Removed (tons)x 1000
Compton M7.45 Palos Verdes M7.38 Redondo Canyon M6.65
Palos Verdes Estates 19.59 27.65 25.40
Rancho Palos Verdes 43.78 69.42 47.23
Rolling Hills 3.34 5.28 2.81
Rolling Hills Estates 20.38 31.88 20.78
Total 87.09 134.23 96.22
7.2.4 Impact on Community Lifelines
The entire Planning Area is vulnerable to earthquakes, including all community lifelines. Functional downtime is the most significant earthquake impact on critical facilities and community lifelines. The severity of this impact is based on the amount of time it takes to restore damaged facilities to operational status. Hazus estimates damage and functional downtime for earthquake scenarios. Refer to Table 7-8 for a summary of community lifelines in the earthquake hazard areas.
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Table 7-8. Community Lifelines in Earthquake Hazard Area City
CommunicationsEnergyFood, Hydration, ShelterHazardous MaterialsHealth and MedicalSafety and SecurityTransportationWater SystemsTotal Palos Verdes Estates TBD TBD TBD TBD TBD TBD TBD TBD TBD Rancho Palos Verdes TBD TBD TBD TBD TBD TBD TBD TBD TBD Rolling Hills TBD TBD TBD TBD TBD TBD TBD TBD TBD
Rolling Hills Estates TBD TBD TBD TBD TBD TBD TBD TBD TBD Total TBD TBD TBD TBD TBD TBD TBD TBD TBD
7.2.5 Impact on the Economy
In the Planning Area, loss of employment and lost property tax basis would be an economic impact. A major earthquake could disrupt, damage, or destroy computer facilities, which could curtail the operations of banks, insurance companies, and other elements of the financial community for a period of time. This may affect local government, businesses, and residents’ ability to make payments and purchases.
7.2.6 Impact on Historic and Cultural Resources
Several sites of the Planning Area, such as the Point Vicente Interpretive Center and the Palos Verdes Library District, feature historic and cultural content dating back over a century. In the event of an earthquake, these sites face a heightened risk of severe damage or total collapse. The loss would not only be structural but also cultural, erasing irreplaceable links to the region’s past.
7.2.7 Impact on Ecosystems and Natural Resources
Earthquakes can cause a range of environmental impacts. Earthquake-induced landslides may severely damage surrounding habitats, while shifts in the earth’s structure can reroute streams, altering water quality and disrupting ecosystems. Groundwater-fed streams or springs may dry up because of changes in underlying geology. Additionally, earthquakes pose a significant risk of hazardous material release through various mechanisms, including the following:
• The toppling of elevated tanks or overturning of horizontal tanks • Structural failures
• Dislodging of asbestos
• Sloshing from open-topped containers
• Storage container failures
• Under- or above-ground pipeline breaks
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7.2.8 Change in Vulnerability Since the Prior Planning Area HMPs There has been little change in earthquake vulnerability in the Planning Area since the prior Planning Area HMPs. The population remains small, and there has been minimal new construction that would alter the Planning Area’s exposure. While seismic risk is inherent because of regional fault lines, the lack of significant development means that overall vulnerability has not increased meaningfully.
7.3 MITIGATION OPPORTUNITIES
Table 7-9 presents a range of potential opportunities considered by the Planning Partnership for mitigating the earthquake hazard.
Table 7-9. Potential Opportunities to Mitigate the Earthquake Hazard Community Scale Organizational Scale Government Scale
Manipulate the Hazard
• None • None • None
Reduce Exposure and Vulnerability
• Locate outside of
hazard area (off soft
soils)
• Retrofit structure
(anchor house
structure to
foundation)
• Secure household
items that can cause
injury or damage (such
as water heaters,
bookcases, and other
appliances)
• Build to higher design
• Locate or relocate
critical functions
outside hazard area
where possible
• Build redundancy for
critical functions and
facilities
• Retrofit critical
buildings and areas
housing critical
functions
• Locate critical facilities or functions outside
hazard area where possible
• Harden infrastructure
• Provide redundancy for critical functions
• Adopt higher regulatory standards
• Perform seismic retrofits for vulnerable critical
buildings and areas
Build Local Capacity
• Practice “drop, cover,
and hold”
• Develop household
mitigation plan, such
as creating a retrofit
savings account,
communication
capability with outside,
72-hour selfsufficiency during an
event
• Keep cash reserves for
reconstruction
• Adopt higher standard
for new construction;
consider
“performance-based
design” when building
new structures
• Keep cash reserves for
reconstruction
• Inform your employees
on the possible
impacts of
earthquakes and how
to deal with them at
your work facility.
• Provide better hazard maps
• Provide technical information and guidance
• Enact tools to help manage development in
hazard areas (e.g., tax incentives, information)
• Include retrofitting and replacement of critical
system elements in capital improvement plan
• Develop strategies to take advantage of postdisaster opportunities • Warehouse critical infrastructure components
such as pipe fittings, valves, pumps, power line,
and road repair materials
• Solidify supplemental power supply to tanks
and pump stations (generator program)
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Community Scale Organizational Scale Government Scale
• Become informed on
the hazard and risk
reduction alternatives
available
• Develop a postdisaster action plan for
your household
• Sign up for early
warning systems
• Sign up for MyShake
• Develop a continuity of
operations plan
• Develop and adopt a continuity of operations
plan
• Initiate triggers guiding improvements (such as
<50% substantial damage or improvements)
• Further enhance seismic risk assessment to
target high hazard buildings for mitigation
opportunities
• Develop a post-disaster action plan that
includes grant funding and debris removal
components
Nature-based Opportunities
• None identified
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Flood 8-1
8. FLOOD
8.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.
8.1.1 Description of the Hazard
Defining the Hazard
Flooding is any overflowing of water onto land that is normally dry, due to rain, ocean waves, or the failure of a dam or levee (NOAA National Severe Storms Laboratory, 2023). Floods are the most common of all weather-related natural disasters. In urban areas, where buildings, highways, driveways, and parking lots reduce the ground’s ability to absorb rainfall, the resulting increase in runoff can overwhelm constructed storm drain systems, resulting in flooding on nearby roads and buildings. The Palos Verdes Peninsula is typically exposed to the following flood types, with each further described below:
• Inland flooding which includes riverine flooding, flash flooding, and urban flooding. • Coastal flooding which includes flood impact from long-term inundation from sea-level rise, tsunami, and coastal erosion.
Inland Flooding
Inland flooding can include riverine flooding, flash flooding, and localized flooding.
Riverine Flooding
Riverine flooding, or fluvial flooding, is when streams and rivers exceed the capacity of their natural or constructed channels to accommodate water flow and water overflows the banks, spilling out into adjacent low-lying, dry land. This occurs when the flow of a river exceeds the bank sides and causes damage or obstruction to a nearby floodplain. Riverine flooding can turn into a flash flood if the river is at or above its flood stage and if the soil is saturated (FEMA, 2025).
Flash Flooding
A flash flood is a rapid inundation of low-lying areas caused by heavy rain associated with severe thunderstorms, tropical systems, or melting water from ice or snow. Flash flooding also occurs far away from water bodies when a large volume of water cannot be absorbed by the soil or storm water systems and travels overland unimpeded (NWS, 2019).
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Urban Flooding
Urban (stormwater) flooding occurs in developed areas when heavy rainfall runoff overwhelms the local stormwater drainage systems (NOAA, 2025). Water that does not evaporate or infiltrate into the ground is carried by conduits to waterways such as creeks, rivers, or the ocean. These drainage systems have two purposes: 1) to control storm water runoff during periods of heavy rainfall; and 2) to minimize disruption of activity from more frequently occurring, less significant storms. Urban flooding occurs when runoff exceeds system capacity, or because systems are blocked from lack of maintenance or other obstruction (NOAA NWS, 2025).
Coastal Flooding
Coastal areas can experience various kinds of flooding related hazards including storm surge, sea level rise, erosion, and tsunami. The combination of these events can result in the total perceived coastal flooding event. Coastal flooding can be caused by a combination of inputs including astronomical tides, El Niño, and storm surge from coastal storms.
Storm Surge
Storm surge is the abnormal rise in seawater level during a storm, measured as the height of the water above the normal predicted astronomical tide. The surge is caused primarily by a storm’s winds pushing water onshore. The amplitude of the storm surge at any given location depends on the orientation of the coastline with the storm track; the intensity, size, and speed of the storm; and the local bathymetry (NOAA, n.d.).
Storm tide is the total observed seawater level during a storm, resulting from the combination of storm surge and the astronomical tide. Astronomical tides are caused by the gravitational pull of the sun and the moon and have their greatest effects on seawater level during new and full moons—when the sun, the moon, and the Earth are in alignment. As a result, the highest storm tides are often observed during storms that coincide with a new or full moon (NOAA, n.d.).
Sea Level Rise
Relative or local sea levels are affected by global sea level fluctuations, changes in land elevation, winds, and ocean circulation. It refers to the height of the water as measured along the coast relative to a specific point on land. Tide stations measure local sea level rise. Water measurements at the tide stations are referenced to stable vertical points on the land, and a known relationship is established. As the temperature of the Earth changes, so does sea level. Temperature and sea level are linked for the following two main reasons (USEPA, 2025):
• Land ice melt: Changes in the volume of water and ice on land (namely glaciers and ice sheets) can increase or decrease the volume of water in the ocean. • Thermal expansion: As water warms, it expands slightly—an effect that is cumulative over the entire depth of the oceans.
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Rising sea level inundates low-lying wetlands and dry land, erodes shorelines, contributes to coastal flooding, and increases the flow of salt water into estuaries and nearby groundwater aquifers. Higher sea level also makes coastal infrastructure more vulnerable to damage from storms (USEPA, 2025).
Tsunami
A tsunami is a series of ocean waves that sends surges of water (potentially reaching heights of over 100 feet) onto land. Tsunamis are primarily caused by underwater earthquakes. The earthquake’s impact displaces the body of water above it, causing a tsunami. They can be unpredictable, continue for hours and cause severe damage along coastal communities. Most of the damage found in the aftermath of a tsunami is due to the surge of water, wave impacts, strong currents, erosion, and debris. This leads to the destruction or damage of structures; disruption of transportation, power and communications; and more (FEMA, 2023a).
Coastal Erosion
Coastal erosion is the loss of sediment along coastal waterways due to waves and currents. Loss of sediment along beaches can lead to a greater risk of collapse of coastal bluffs. Erosional events can occur rapidly from a single storm event or take place gradually with incremental losses taking place over weeks, months, and years.
Some methods used in the past to stop or reduce coastal erosion actually exacerbated the problem.
Shore protection structures such as seawalls and revetments often are built to stabilize the upland property, but they can subject down-drift beaches to increased erosion. Typically, they eliminate natural wave run-up and sand deposition processes and can increase reflected wave action and currents at the waterline. Increased wave action can cause localized scour in front of structures and prevent settlement of suspended sediment (FEMA, 1996).
Cause of the Hazard
Inland flooding typically occurs when prolonged rain falls over several days, when intense rain falls over a short period of time, or when a debris jam causes a river or stream to overflow onto the surrounding area. The most common cause of flooding is water due to rain that accumulates faster than soils can absorb it or rivers can carry it away (NWS, n.d.).
The California DWR defines the following causes of inland and coastal flood hazards (DWR, 2019):
• Riverine Flooding occurs when rivers, streams, and lakes overflow their banks. This includes flooding caused by levee failure and channel erosion. Areas adjacent to local streams and creeks can also experience flooding as a result of excessive runoff from heavy rainfall and accumulation of water flowing over broad flat areas
• Flash Flooding is a sudden, rapid flooding of low-lying areas typically caused by intense rainfall.
Flash floods can also occur from the collapse of a manmade structure. Rapidly rising water can reach heights of 30 feet or more.
• Urban Flooding occurs in both urban and non-urban areas during or after a storm. Any storm, particularly slow-moving, steady rainstorms, can overwhelm drainage systems. When the system backs up, pooling water can flood streets, yards, and even the lower floors of homes and
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businesses. Even less intense storms can cause this type of flooding when leaves, sediment, and debris plug storm drains.
• Coastal Flooding happens through a process known as “storm surges,” when ocean waves are significantly larger than normal. If a storm event corresponds with a higher than normal tide, extensive flooding can occur. Winds blowing in an onshore direction (from the sea toward the land) can cause the water to “pile up” against the coast, overtopping natural and manmade flood protection structures like sea walls. Coastal communities, especially in low-lying areas, are highly susceptible to this hazard (DWR 2019).
Tsunamis are primarily caused by underwater earthquakes. The earthquake’s impact displaces the body of water above it, causing a tsunami. Other causes of tsunamis include landslides, volcanic activity, certain types of severe weather and—potentially—near-Earth objects like asteroids or comets that collide with or explode above the ocean (FEMA, 2023a).
Summary of Potential Impacts
Flooding in the Palos Verdes Peninsula can have significant impacts on the people, structures, infrastructure, and natural environment. Roads, bridges, and buildings can be severely damaged or destroyed, making transportation difficult and disrupting daily life and emergency response efforts.
Hydrostatic pressures and flowing floodwaters can easily cause structures to collapse or float away.
This can lead to costly repairs and loss of property value, impacting homeowners and businesses.
Floodwaters can contaminate drinking water and lead to the spread of contaminants and diseases.
During severe flood events, residents may need to evacuate their homes, which can lead to displaced residents and the potential increased risk of drowning during evacuation efforts. Flooding can result in scouring and erosion of sediment in areas with flow or wave action.
Cascading Hazard Impacts
Flooding often initiates a series of cascading hazards that extend beyond direct inundation caused by a flood event. One of the most significant secondary impacts is bank and bluff erosion. In many cases, the threat and effects of erosion are worse than actual flooding. This is particularly evident along steep river reaches, canyons, and coastal bluffs, where fast‑moving floodwaters may recede quickly but aggressively scour banks and slopes, destabilizing land and progressively encroaching on adjacent properties.
Flood impacts can be further amplified when precipitation‑driven riverine or urban flooding coincides with coastal flooding, resulting in elevated total water levels and more widespread or prolonged flooding than would occur from a single source alone. Prolonged soil saturation from high flows can also trigger landslides and slope failures, especially in areas with steep terrain or pre‑existing instability. In addition, floodwaters can mobilize hazardous materials when storage tanks or containment systems fail, allowing pollutants to enter waterways or drainage systems.
Along coastal areas, flood events intensify erosion through increased storm-driven wave energy, coastal inundation, and surface runoff that undercut bluffs and destabilize slopes within active landslide complexes. Heavy rainfall combined with elevated ocean conditions has been shown to accelerate bluff retreat and landslide movement, increasing risks to coastal infrastructure, roadways, and residential development (NASA, 2025).
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8.1.2 National Flood Insurance Program Participation
Properties constructed after adoption of a FIRM or DFIRM are considered less vulnerable to flooding because they were constructed after adoption of regulations and codes to decrease vulnerability.
Properties built before adoption of a FIRM or DFIRM are more vulnerable to flooding because either they do not meet code or are within hazardous areas.
Table 8-2 lists flood insurance statistics for the cities of the Palos Verde Peninsula, the Planning Area municipalities that participate in the NFIP. As of December 31, 2025, 133 policies were in force for the Planning Area, providing more than $43.6 million in insurance. There were two repetitive loss (RL) properties in the City of Palos Verde Estates jurisdiction.
Table 8-1. Riverine Flooding Sources in the Palos Verde Peninsula City
Date of
Entry
Current
FIRM Date
Flood Insurance Policies
Insurance in
Force
Annual
Premiums
ClaimsRL or SRL Properties
Value of
Claims
Palos Verdes
Estates
November
21, 2001
April 21,
2021
49 $15,976,000 $42,514 15 2 $39,750
Rancho Palos
Verdes
September
26, 2008
April 21,
2021
51 $16,218,000 $35,640 8 - $261,095
Rolling Hills September
26, 2008
NSFHA 19 $6,650,000 $11,000 1 - -
Rolling Hills
Estates
September
26, 2008
NSFHA 14 $4,727,000 $9,074 9 - $12,344
Total 133 $43,571,000 $98,228 33 2 $313,189
Source: (FEMA, 2025)
To be eligible to participate in the NFIP, a local government must possess the authority to adopt codes and standards to regulate development in the Special Flood Hazard Area. The special purpose district planning partners do not possess these authorities and are therefore not listed in this section.
8.1.3 Location
Inland Flooding
Riverine and flash flooding occurs along rivers and streams in the Palos Verdes Peninsula. Table 8-2 identifies the potential riverine flooding sources for the Planning Area.
Table 8-2. Riverine Flooding Sources in the Palos Verde Peninsula Flooding Source Community HUC-8 Subbasin(s)
Agua Amarge Canyon Creek City of Palos Verdes Estates 18070104 Malaga Canyon Creek City of Palos Verdes Estates 18070104 Unnamed Stream Main Reach City of Palos Verdes Estates 18070104
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Flooding Source Community HUC-8 Subbasin(s)
Unnamed Stream Tributary 1 City of Palos Verdes Estates 18070104 Unnamed Stream Tributary 2 City of Palos Verdes Estates 18070104 UNKNOWN 1 to Malaga Canyon Creek City of Palos Verdes Estates 18070104 UNKNOWN 2 to Malaga Canyon Creek City of Palos Verdes Estates 18070104 Source: (FEMA, 2021)
Floodplains
The land area susceptible to being inundated or flooded by water from any source (e.g., river, stream, lake, estuary) is referred to as a floodplain. The floodplain includes the floodway and the floodway fringe to convey the flood event and provide flood water storage. These areas form a complex physical and biological system that not only supports a variety of natural resources but also provides natural flood and erosion control. However, not all flooding occurs in such areas. Flash and urban flooding often occur outside of designated floodplain areas.
Flood hazard areas are identified as Special Flood Hazard Area (SFHA). SFHAs are defined as the area that will be inundated by the flood event having a 1 percent chance of being equaled to or exceeded in any given year. The
1 percent annual chance floodplain establishes the area that has flood insurance and floodplain management
requirements. The following are additional definitions
relating to flood maps (FEMA 2025):
• Flood hazard areas identified on the Flood
Insurance Rate Map (FIRM) are identified as a
SFHA.
• SFHA is the area that will be inundated by the flood
event having a 1 percent chance of being equaled or
exceeded in any given year.
• SFHAs are labeled as Zone A, Zone AO, Zone AH, Zones A1-A30, Zone AE, Zone A99, Zone AR, Zone AR/AE, Zone AR/AO, Zone AR/A1-A30, Zone AR/A, Zone V, Zone VE, and Zones V1-V30. • Zone B or Zone X (shaded) = Moderate flood hazard areas and are the areas between the limits of the base flood and the 0.2 percent annual chance (or 500-year) flood. • Zone C or Zone X (unshaded) = Areas of minimal flood hazard, which are the areas outside the SFHA and higher than the elevation of the 0.2 percent annual chance flood, are labeled.
In the Planning Area, FEMA has designated several areas along canyons and creeks, such as the Malaga Creek and Margate Canyon Creek, as SFHAs due to their susceptibility to seasonal flooding and runoff from steep terrain. These mapped areas are subject to federal floodplain management regulations under the NFIP, and property owners in these zones may be required to carry flood insurance if they have federally backed mortgages.
The 1-percent annual chance flood
is also referred to as the base flood
or 100-year flood. The 1-percent
annual chance floodplain is also
commonly referred to as the 100-
year floodplain.
A 100-year flood is not a flood that
will occur once every 100 years; the
designation indicates a flood that
has a 1-percent chance of being
equaled or exceeded each year.
Thus, the 100-year flood could occur
more than once in a relatively short
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Figure 8-1 displays the FEMA 1 percent annual chance flood zone for the Palos Verde Peninsula.
Figure 8-1. FEMA 1 Percent Annual Chance Flood Zone
Table 8-3 summarizes the number of acres in Planning Area in the mapped FEMA floodplain.
Table 8-3. Acres of Floodplain in FEMA 1 Percent Annual Chance Flood Zones City Acres of Floodplain
Palos Verdes Estates 111
Rancho Palos Verdes 70
Rolling Hills 0
Rolling Hills Estates 0
Total 180
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Coastal Flooding
Storm Surge
The Southern California coastline is exposed to waves generated by winter and summer storms originating in the Pacific Ocean. It is not uncommon for these storms to cause 15-foot breakers. The occurrence of such a storm event in combination with high astronomical tides and strong winds can cause a significant wave runup and allow storm waves to attack higher than normal elevations along the coastline. When this occurs, shoreline erosion and coastal flooding frequently results in damage to inadequately protected structures and facilities located along low-lying portions of the shoreline.
Sea Level Rise
The potential for sea level rise flooding is confined to very limited Planning Areas along the coast because of the topography of the region, defined primarily by coastal bluffs.
Figure 8-2. 25 cm Sea Level Rise with 100-Year Storm Surge
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Figure 8-3. 100 cm Sea Level Rise with 100-Year Storm Surge
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Tsunami
Areas prone to flooding from a tsunami include low-lying coastal areas. These are very limited in the Planning Area due to the topography of the region, defined primarily by coastal bluffs. Figure 8-4 displays the tsunami inundation area for the Planning Area.
Figure 8-4 Tsunami Hazard Area
8.1.4 Extent
Measuring Intensity
Flood categories are defined for each gage location that describe or categorize the observed or expected severity of flood impacts in the corresponding stream segment or nearby stream. The severity of flooding at a given stage is not necessarily the same at all locations along a stream because of varying channel/bank characteristics on portions of the stream. Therefore, the stage for a given flood category is usually associated with lowest water level corresponding to the most significant flood impacts
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somewhere in the reach. The flood categories used in the NWS are the following (NWS, High Water Level Terminology, n.d.):
• Minor Flooding—Minimal or no property damage, but possibly some public threat. A Flood Advisory product is issued to advise the public of events that are expected not to exceed the minor flood category.
• Moderate Flooding—Some inundation of structures and roads near streams. Some evacuations of people or transfer of property to higher elevations are necessary. A Flood Warning should be issued if moderate flooding is expected during the event. • Major Flooding—Extensive inundation of structures and roads. Significant evacuations of people or transfer of property to higher elevations. A Flood Warning should be issued if major flooding is expected during the event.
The three flood categories do not necessarily exist for each gage location. Most commonly, gages in remote areas may not have a major flood stage assigned. Record flooding is flooding that equals or exceeds the highest stage or discharge at a given site during the period of recordkeeping.
The NWS also categorizes coastal flooding into three levels of severity: minor, moderate, and major. The classifications measure how much water levels exceed average astronomical high tide for that location (NOAA NOS, n.d.):
• Minor High Tide Flooding—water levels reach 0.55 meters (1.8 feet) above average high tide. This minor flooding is mostly disruptive, causing stormwater backups and road closures. • Moderate High Tide Flooding—0.85 meters (2.8 feet) above average high tide. This can cause more disruption and damage homes and businesses.
• Major Flooding—1.20 meters (3.9 feet) above average high tide. Floods of this severity are destructive, may lead to evacuations, and often require repairs to infrastructure and property.
Warning Time
Because of the sequential pattern of meteorological conditions needed to cause serious flooding, it is unusual for a flood to occur without warning. Warning times for floods can be between 24 and 48 hours.
Flash flooding can be less predictable, but potential hazard areas can be warned in advanced of potential flash flooding danger.
Each watershed has unique qualities that affect its response to rainfall. A hydrograph, which is a graph showing stream flow in relation to time, is a useful tool for examining a stream’s response to rainfall.
Once rainfall starts falling over a watershed, runoff begins, and the stream begins to rise. Water depth in the stream channel (stage of flow) will continue to rise in response to runoff even after rainfall ends.
Eventually, the runoff will reach a peak and the stage of flow will crest. It is at this point that the stream stage will remain the most stable, exhibiting little change over time until it begins to fall and eventually subside to a level below flooding stage.
The potential warning time a community has to respond to a flooding threat is a function of the time between the first rainfall and the first occurrence of flooding. The time it takes to recognize a flooding threat reduces the potential warning time to the time that a community has to take actions to protect
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lives and property. Another element that characterizes a community’s flood threat is the length of time floodwaters remain above flood stage.
The NWS issues warnings or advisories when confidence is greater than 80 percent that an event will occur. Depending on the type of event, these may be issued anywhere from hours before an event to days in advance of an event. Warnings include the following (NWS, Flood Related Products, n.d.):
• Flash Flood Warning: A Flash Flood Warning is issued to inform the public, emergency management and other cooperating agencies that flash flooding is in progress, imminent, or highly likely. Flash Flood Warnings are urgent messages as dangerous flooding can develop very rapidly, with a serious threat to life and/or property. Flash Flood Warnings are usually issued minutes to hours in advance of the onset of flooding.
• Flash Flood Watch: A Flash Flood Watch is issued to indicate current or developing conditions that are favorable for flash flooding. The occurrence is neither certain nor imminent. A watch is typically issued within several hours to days ahead of the onset of possible flash flooding. • Flood Warning: A Flood Warning is issued to inform the public of flooding that poses a serious threat to life and/or property. A Flood Warning may be issued hours to days in advance of the onset of flooding based on forecast conditions. Floods occurring along a river usually contain river stage (level) forecasts.
• Flood Watch: A Flood Watch is issued to indicate current or developing conditions that are favorable for flooding. The occurrence is neither certain nor imminent. A watch is typically issued within several hours to days ahead of the onset of possible flooding. In situations where a river or stream is expected to be the main source of the flooding, forecast confidence may allow for a Flood Watch to be issued several days in advance.
• Flood Advisory: A Flood Advisory is issued when a flood event warrants notification but is less urgent than a warning. Advisories are issued for conditions that could cause a significant inconvenience, and if caution is not exercised, could lead to situations that may threaten life and/or property.
A Flood Advisory product is issued to advise the public of events that are expected not to exceed the minor flood category. A Flood Warning should be issued if moderate or major flooding is expected during the event.
Worst-Case Scenario
The worst-case scenario is a series of storms that flood numerous drainage basins in a short time. This would overwhelm local response and floodplain management departments. Major roads would be blocked, preventing access for many residents and critical functions. High runoff flows could cause rivers to scour, possibly washing out roads and creating more isolation problems.
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8.1.5 Previous Occurrences
The following sections provide a review of previous flood occurrences in the Planning Area.
Declarations
Federal Declarations
Between 2019 and 2025, the Planning Area experienced five major disaster (DR) or emergency declarations (EM) related to a flood hazard.
Table 8-4. Federal Flood Disaster Declarations
Disaster Number Incident Period Declaration Date Description DR-4683-CA December 27, 2022 –
January 31, 2023
January 14, 2023 Severe Winter Storms,
Flooding, Landslides, and
Mudslides
EM-3591-CA January 8 – January 31,
2023
January 9, 2023 Severe Winter Storms,
Flooding, and Mudslides
DR-4699-CA February 21 – July 10,
2023
April 3, 2023 Severe Winter Storms,
Straight-Line Winds,
Flooding, Landslides, and
Mudslides
EM-3592-CA March 9 – July 10, 2023 March 10, 2023 Severe Winter Storms, Flooding, Landslides, and
Mudslides
DR-4769-CA January 31– February 9,
2024
April 13, 2024 Severe Winter Storms,
Tornadoes, Flooding,
Landslides, and
Mudslides
Source: OpenFEMA Datasets (OpenFEMA Data Sets | FEMA.gov) State Proclamations
Between 2019 and 2025, California included Los Angeles County in 10 state-proclaimed flood disasters.
Table 8-5. State Landslide Disaster Declarations
Disaster Number Declaration Date Description
- November 17, 2021 January 2021 Winter Storms
- September 16, 2022 Tropical Storm Kay
N-1-23, N-2-23, N-10-23 January 4, 2023 December 2022 to January 2023 Storms CA23-1 January 4, 2023 Late December 2022 Storms
CA23-3 March 1, 2023 Late February-Early March 2023 Winter Storms CA23-3 June 16, 2023 February 2023 Winter Storms
- August 19, 2023 Tropical Storm Hilary
- February 4, 2024 Early February 2024 Storms
- March 3, 2024 March 2024 Storms
- June 21, 2024 January 2024 Winter Storms
Source: (Cal OES, 2025)
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USDA Declarations
Between 2019 and 2025, the USDA declared that Los Angeles County experienced one disaster relating to flood.
Table 8-6. USDA Drought Disaster Declarations
Designation Number Event Begin Date Description
S5658 August 9, 2023 Tropical Storm Hillary
Source: (U.S. Department of Agriculture, 2025)
Summary of Significant Events
Significant and damaging atmospheric river flood event that occurred in the winters of 2022-2023 which caused and resulted in land movement in the fall of 2023 and early 2024 in the Planning Area.
Recent Events
The NOAA NCEI Storm Events Database reported 75 flood events impacting Los Angeles County forecast zones from 2019 through 2025, three of which impacted areas adjacent to the Planning Area (NOAA NCEI, 2025). The Planning Area experienced the atmospheric river that occurred in the winter of 2023- 2024, delivering short-duration rainfall events that resulted in flash flooding warnings from February 1 – February 5, 2024. Table 8-7 shows a summary of significant flood events impacting the Planning Area (NOAA NCEI, 2025).
Table 8-7. Recent Flood Hazard Events
Date (s) of Event Event Type
FEMA / State
Declaration
Number (if
applicable)
Los Angeles
County
included in
declaration? Description
January 9 –
January 14, 2023
Flood/Severe Winter
Storm
DR-4683-CA Yes Heavy rainfall across Los
Angeles County resulting in
flash flooding, landslides, and
impact to transportation.
January 9, 2023 Flood/Severe Winter
Storm
EM-3591-CA Yes Heavy rainfall generated flash
flooding and significant mud
and debris flows.
April 3, 2023 Flood/Severe Winter
Storm
DR-4699-CA Yes Heavy rainfall generated flash
flooding and significant mud
and debris flows across Los
Angeles County.
March 10, 2023 Flood/Severe Winter
Storm
EM-3592-CA Yes Winter storm conditions
developed across the
mountains of Los Angeles
County with heavy
precipitation and resulting
landslides.
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Date (s) of Event Event Type
FEMA / State
Declaration
Number (if
applicable)
Los Angeles
County
included in
declaration? Description
August 9, 2023 Tropical Storm NA NA Tropical Storm Hilary delivered record August
rainfall for Los Angeles
County and widespread
flooding/debris flows across
Southern California.
February 1 –
February 5, 2024
Flood/Flash Flood NA NA Flash Flood Warning covering
Rancho Palos Verdes, Long
Beach, Lomita, and Carson on
February 1, 2024. Palos
Verdes Drive South was
temporarily closed because
of mud and rock slides that
morning.
April 13, 2024 Flood/Severe Winter
Storm
DR-4769-CA Yes A powerful winter storm
impacted all of Southwestern
California including
tornadoes, flooding,
landslides, and mudslides.
Source: (NOAA NCEI, 2025); (FEMA, 2025)
8.1.6 Future Conditions
Future hazard conditions, including frequency and severity of future events, is discussed in the sections below.
Probability
The chance of heavy flooding and flash flooding is greatest during California’s rainy season from November to April. However, the diversity of climate patterns in California makes flooding more than a seasonal risk. The following are some of the weather and climate conditions that have a significant impact on the occurrence of flooding (Cal OES, 2023):
• El Niño conditions
• La Niña conditions
• Desert monsoons
• Tropical storms
• Gulf of Alaska storms
• Atmospheric river patterns
The number of years between floods of any given size varies because of the natural variations in climate and weather events. FEMA conducts flood studies that use historical records to determine the probability of occurrence for different flood levels in a community. FEMA FIRMs identify the flood hazard area as the area that would be inundated by a flood with a 1 percent chance of occurring in any given year (the
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1-percent annual chance flood). FIRMs also typically show the extent of the flood with a 0.2 percent chance of occurring in any given year (0.2 percent annual chance flood). These measurements reflect statistical averages only, and it is possible for two or more floods with a 1 percent annual chance to occur in a short time period (USGS, n.d.). Table 8-8summarizes the concept of recurrence intervals and probabilities.
Table 8-8. Recurrence Intervals and Probabilities of Occurrence Recurrence Interval (in years) Probability of Being Equaled or Recurrence Interval (in years) 100 1 in 100 1%
50 1 in 50 2%
25 1 in 25 4%
10 1 in 10 10%
5 1 in 5 20%
2 1 in 2 50%
Source: (USGS, n.d.)
Flooding is common in California and can take place any time of the year. Based on historical flood events, the State has a high probability of future riverine, flash, localized, and alluvial fan flood events.
The frequency and severity of fluvial flooding for river systems are based on “discharge probability.” The discharge probability is the probability that a certain river discharge (flow) level will be equaled or exceeded in a given year. Flood studies use historical records to determine the probability of occurrence for different discharge levels. These measurements reflect statistical averages only; it is possible for multiple floods with a low probability of occurrence (such as a 1 percent annual chance flood) to occur in a short time period. A single flood event can have flows at different points on a river or stream that correspond to different probabilities of occurrence.
Climate Change
Climate change plays a significant role in the increasing frequency and intensity of extreme weather events, particularly floods. According to scientific reports, as global temperatures rise, the hydrological cycle becomes more dynamic and unpredictable. Warmer air holds more moisture, which often leads to heavier and more intense rainfall. This accelerates the risk of flooding, as seen in numerous impactful events around the world. Additionally, the shift in weather patterns caused by climate change contributes to prolonged periods of drought in some regions, further exacerbating water-related challenges.
Use of historical hydrologic data has long been the standard of practice for designing and operating water supply and flood protection projects. For example, historical data are used for flood forecasting models and to forecast snowmelt runoff for water supply. This method of forecasting assumes that the climate of the future will be similar to that of the period of historical record. However, the hydrologic record cannot be used to predict changes in frequency and severity of extreme climate events such as floods. Scientists project greater storm intensity with climate change, resulting in more direct runoff and flooding. High frequency flood events in particular will likely increase with a changing climate. What is currently considered a 1 percent annual chance also may strike more often, leaving many communities at greater risk. Going forward, model calibration must happen more frequently, new forecast-based tools must be developed, and a standard of practice that explicitly considers climate change must be adopted.
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Climate change is already impacting water resources, and resource managers have observed the following:
• Historical hydrologic patterns can no longer be solely relied upon to forecast the water future. • Precipitation and runoff patterns are changing, increasing the uncertainty for water supply and quality, flood management and ecosystem functions.
• Extreme climatic events will become more frequent, necessitating improvement in flood protection, drought preparedness and emergency response.
Climate change will also increase other hazards that contribute to flood risk, most notably wildfires. According to California’s Fourth Climate Change Assessment, continued increases in greenhouse gas emissions are expected to drive a substantial rise in large wildfires, with a projected 50 percent increase in fires over 25,000 acres and a 77 percent increase in average area burned by 2100.
Post‑fire landscapes are highly vulnerable: vegetation loss and soil damage make it easier for rain to trigger destructive debris flows and mudflows. When storms pass over recently burned areas, runoff can carry ash, sediment, and debris downslope, dramatically intensifying flood impacts and causing significant damage (Refer to Figure 8-5) (Cal OES, 2023).
Potential Future Impacts
The Planning Area is well-equipped to manage growth in floodplains with flood damage prevention ordinances, its building codes, and the Safety Element of the municipal General Plans. Collectively, these tools help limit exposure to flood hazards by regulating development in floodplains, requiring flood‑resistant construction standards, and guiding land‑use decisions away from the highest‑risk areas. Continued enforcement and periodic updates to these regulatory frameworks will be critical to maintaining community resilience, minimizing property damage, and protecting public safety over the long term.
Figure 8-5. How Wildfires Cause
Flooding
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8.2 VULNERABILITY ASSESSMENT
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(ii) The plan must include a description of the jurisdiction’s vulnerability to the hazards of concern and include an overall summary of the hazard’s impact on the community. The impacts need to include the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the hazard areas, and estimate of potential dollar losses to vulnerable structures, and a description of land uses and development trends.
8.2.1 Summary of Vulnerability
Flood vulnerability in the Planning Area is focused within the floodplain; however, flooding also takes place outside the floodplain during severe rainfall events and in areas of urban flooding. A Hazus Level 2 user-defined analysis was performed for general building stock, critical facilities and infrastructure in the flood zones.
8.2.2 Impact on Life, Health, and Safety
Floods present threats to public health and safety. Floodwater is generally contaminated by pollutants such as sewage, human and animal feces, pesticides and insecticides, fertilizers, oil, asbestos, and rusting building materials. The following health and safety risks are commonly associated with flood events:
• Unsafe food—Floodwaters contain disease-causing bacteria, dirt, oil, human and animal wastes, and farm and industrial chemicals. They carry away whatever lies on the ground and upstream.
Their contact with food items, including food crops in agricultural lands, can make that food unsafe to eat and hazardous to human health. Power failures caused by floods damage stored food. Refrigerated and frozen foods are affected during the outage periods, and thus must be carefully monitored and examined prior to consumption. Foods kept inside cardboard, plastic bags, jars, bottles, and paper packaging are subject to disposal if contaminated by floodwaters.
Even though the packages do not appear to be wet, they may be unhygienic with mold contamination and deteriorate rapidly.
• Contaminated drinking/washing water and poor sanitation—Flooding impairs clean water sources with pollutants and affects sanitary toilets. Direct and indirect contact with the contaminants—whether through direct food intake, vector insects such as flies, unclean hands, or dirty plates and utensils—can result in waterborne infectious disease. Wastewater treatment plants, if flooded and caused to malfunction, can be overloaded with polluted runoff waters and sewage beyond their disposal capacity, resulting in backflows of raw sewage to homes and lowlying grounds. Private wells can be contaminated or damaged severely by floodwaters, while private sewage disposal systems can become a cause of infection and illnesses if they are broken or overflow. Unclean drinking and washing water and sanitation, coupled with lack of adequate sewage treatment, can lead to disease outbreaks, including life-threatening cholera, typhoid, dysentery, and some forms of hepatitis.
• Mosquitoes and animals—Prolonged rainfall and floods provide new breeding grounds for mosquitoes—wet areas and stagnant pools—and can lead to an increase in the number of
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mosquito-borne diseases such as malaria and dengue and West Nile fevers. Rats and other rodents and wild animals also can carry viruses and diseases. The public should avoid such animals and should dispose of dead animals in accordance with guidelines issued by local animal control authorities.
• Molds and mildews—Excessive exposure to molds and mildews can cause flood victims— especially those with allergies and asthma—to contract upper respiratory diseases and to trigger cold-like symptoms such as sore throat, watery eyes, wheezing and dizziness. Molds grow in as short a period as 24 to 48 hours in wet and damp areas of buildings and homes that have not been cleaned after flooding, such as water-infiltrated walls, floors, carpets, toilets, and bathrooms. Very small mold spores can be easily inhaled by human bodies and, in large enough quantities, cause allergic reactions, asthma episodes, and other respiratory problems. Infants, children, elderly people and pregnant women are considered most vulnerable to mold-induced health problems.
• Carbon monoxide poisoning—Carbon monoxide poisoning is a potential hazard after major floods. Carbon monoxide can be found in combustion fumes, such as those generated by small gasoline engines, stoves, generators, lanterns and gas ranges, or by burning charcoal or wood. In the event of power outages following floods, flood victims tend to use alternative sources of fuels for heating, cooling, or cooking inside enclosed or partly enclosed houses, garages or buildings without an adequate level of air ventilation. Carbon monoxide builds up from these sources and poisons the people and animals inside.
• Hazards when reentering and cleaning flooded homes and buildings—Flooded buildings can pose health hazards after floodwaters recede. Electrical power systems can become hazardous.
People should avoid turning on or off the main power while standing in floodwater. Gas leaks from pipelines or propane tanks can trigger explosion when entering and cleaning damaged buildings or working to restore utility service. Flood debris—such as broken bottles, wood, stones, and walls—may cause wounds and injuries when cleaning damaged buildings. Containers of hazardous chemicals, including pesticides, insecticides, fertilizers, car batteries, propane tanks and other industrial chemicals, may be hidden or buried under flood debris. A health hazard can also occur when hazardous dust and mold in ducts, fans and ventilators of air-conditioning and heating equipment are circulated through a building and inhaled by those engaged in cleanup. • Mental stress and fatigue—Exposure to extreme disaster events can cause psychological distress. Having experienced a devastating flood, seen loved ones lost or injured, and homes damaged or destroyed, flood victims can experience long-term psychological impact. The expense and effort required to repair flood-damaged homes places severe financial and psychological burdens on the people affected, in particular the unprepared and uninsured. Postflood recovery—especially when prolonged—can cause anxiety, anger, depression, lethargy, hyperactivity, sleeplessness, and, in an extreme case, suicide. Behavior changes may also occur in children. There is also a long-term concern among the affected that their homes can be flooded again in the future.
Equity Priority Communities
Vulnerable populations are defined as individuals with physical or mobility limitations, cognitive impairments, and economic constraints that may hinder their ability to prepare for, respond to, or recover from flood hazard events. Within the Planning Area, these populations may reside in locations served by
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a single means of ingress and egress, which can significantly increase their risk during flood events. High floodwaters, roadway washouts, or other flood‑related infrastructure damage can delay or prevent evacuation, limit access for emergency responders, and isolate residents for extended periods. These conditions heighten the potential for injury, health complications, and delayed assistance, particularly for individuals who require mobility aids, medical support, or external assistance during emergencies.
8.2.3 Impact on General Building Stock
Many buildings, especially in older or rural communities, were constructed before modern floodplain management standards were adopted, making them more susceptible to water damage. Flooding can lead to significant structural damage, mold growth, and long-term deterioration of foundations and materials, especially in homes and public buildings not elevated above base flood elevations. These impacts not only threaten the physical integrity of the building stock but also strain local resources for repair and recovery.
Property exposure and losses were estimated through the Level 2 Hazus analysis for the assessed flood zones. Table 8-9 and Table 8-10 show the estimates for the flood exposure and damage to structures and building contents with the percent of total replacement value. Table 8-11 summarizes the number of structures and type of occupancy in the mapped flood risk areas.
Table 8-9. Exposure Estimates for Flood Hazard Areas
City
No. of
Buildings
Exposed
Value of
Buildings
Exposed
Value of
Contents
Exposed
Total
Replacement
Cost Value
% of Total
Replacement
Value
100-year Flood
Palos Verdes Estates 4 $4,467,630 $2,233,815 $6,701,445 0.1% Rancho Palos Verdes 3 $572,625 $286,312 $858,937 0.0%
Rolling Hills 0 $0 $0 $0 0.0%
Rolling Hills Estates 0 $0 $0 $0 0.0%
Total 7 $5,040,255 $2,520,127 $7,560,382 0.0%
Sea Level Rise
Palos Verdes Estates 0 $0 $0 $0 0.0%
Rancho Palos Verdes 0 $0 $0 $0 0.0%
Rolling Hills 0 $0 $0 $0 0.0%
Rolling Hills Estates 0 $0 $0 $0 0.0%
Total 0 $0 $0 $0 0.0%
Tsunami
Palos Verdes Estates 1 $678,902 $678,902 $1,357,804 0.0% Rancho Palos Verdes 10 $2,119,499 $1,059,749 $3,179,248 0.0% Rolling Hills 0 $0 $0 $0 0.0%
Rolling Hills Estates 0 $0 $0 $0 0.0%
Total 11 $2,798,401 $1,738,651 $4,537,052 0.0%
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Table 8-10. Loss Estimates for 100-year Flood Hazard Areas City
Structure Debris
(Tons)
Buildings
Impacted
Total Value Damaged
(Structure & Contents) % of Total Value
Palos Verdes Estates 193 2 $449,110 0.0%
Rancho Palos Verdes 140 2 $129,534 0.0%
Rolling Hills 0 0 $0 0.0%
Rolling Hills Estates 0 0 $0 0.0%
Total 334 4 $578,644 0.0%
Table 8-11. Estimated Number of Buildings by Type, Located in the Flood Hazard Areas City
ResidentialCommercialIndustrialAgricultureReligionGovernmentEducationTotal 100-year Flood
Palos Verdes Estates 4 0 0 0 0 0 0 4
Rancho Palos Verdes 3 0 0 0 0 0 0 3
Rolling Hills 0 0 0 0 0 0 0 0
Rolling Hills Estates 0 0 0 0 0 0 0 0
Total 7 0 0 0 0 0 0 7
Sea Level Rise
Palos Verdes Estates 0 0 0 0 0 0 0 0
Rancho Palos Verdes 0 0 0 0 0 0 0 0
Rolling Hills 0 0 0 0 0 0 0 0
Rolling Hills Estates 0 0 0 0 0 0 0 0
Total 0 0 0 0 0 0 0 0
Tsunami
Palos Verdes Estates 1 0 0 0 0 0 0 1
Rancho Palos Verdes 10 0 0 0 0 0 0 10
Rolling Hills 0 0 0 0 0 0 0 0
Rolling Hills Estates 0 0 0 0 0 0 0 0
Total 11 0 0 0 0 0 0 11
8.2.4 Impact on Community Lifelines
As most flooding in the Planning Area are riverine, stream and waterway overflow and drainage events, these types of flooding often result in property damage, road washouts, and transportation disruptions.
General impacts of these events may include commercial and residential structural damage. Loss of water, power, roads, phones, and transportation may occur, which can be particularly dangerous for those with certain medical conditions. Critical facilities and community lifelines exposed to the riverine flood hazard are likely to experience functional downtime following a flood event, which could increase the net impact of the event. Refer to Table 8-12 for a summary of community lifelines in the flood hazard areas.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Flood 8-22
Table 8-12. Community Lifelines in Flood Hazard Areas
City
CommunicationsEnergyFood, Hydration, ShelterHazardous MaterialsHealth and MedicalSafety and SecurityTransportationWater SystemsTotal 100-year Flood
Palos Verdes Estates 0 0 0 0 0 0 0 0 0
Rancho Palos Verdes 0 0 0 0 0 0 0 0 0
Rolling Hills 0 0 0 0 0 0 0 0 0
Rolling Hills Estates 0 0 0 0 0 0 0 0 0
Total 0 0 0 0 0 0 0 0 0
Sea Level Rise
Palos Verdes Estates 0 0 0 0 0 0 0 0 0
Rancho Palos Verdes 0 0 0 0 0 0 0 0 0
Rolling Hills 0 0 0 0 0 0 0 0 0
Rolling Hills Estates 0 0 0 0 0 0 0 0 0
Total 0 0 0 0 0 0 0 0 0
Tsunami
Palos Verdes Estates 0 0 0 0 0 0 0 0 0
Rancho Palos Verdes 0 0 0 0 0 1 0 0 1
Rolling Hills 0 0 0 0 0 0 0 0 0
Rolling Hills Estates 0 0 0 0 0 0 0 0 0
Total 0 0 0 0 0 1 0 0 0
8.2.5 Impact on the Economy
Flooding can lead to significant economic impacts, including damage to infrastructure, businesses, and property, as well as disruptions to transportation and supply chains.
8.2.6 Impact on Historic and Cultural Resources
Historic structures were not constructed to the modern building code and are less likely to be able to withstand the forces of flooding events. This may result in structures being pushed off their foundations, collapses, and other structural failures. Intense rainfall and runoff can also increase moisture intrusion, sediment deposition, and access limitations, complicating preservation efforts and potentially resulting in the loss of irreplaceable cultural resources over time.
8.2.7 Impact on Ecosystems and Natural Resources
Floods can have both beneficial and detrimental effects on ecosystems and natural resources, including habitat destruction, erosion, water contamination, and changes to soil fertility, while also potentially recharging groundwater and creating new habitats. Seasonal floods can renew ecosystems, providing
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Flood 8-23
life-giving waters in more ways than one. Floods transport vital nutrients, such as nitrogen, phosphorus, and organic material, to the surrounding land. When the water recedes, it leaves behind nutrient-rich sediment on the floodplains, enhancing soil fertility and promoting biodiversity. Floods can also help recharge groundwater supplies and create new aquatic habitats that support a variety of species.
However, floods can also cause significant ecological disruption. Rapid or severe flooding may lead to habitat destruction, increased erosion, water contamination, and the displacement of wildlife. Heavy rainfall can quickly overwhelm river systems, leading to flash floods that threaten both natural environments and human infrastructure.
8.2.8 Change in Vulnerability Since the Prior Planning Area HMPs The Planning Area is well-equipped to manage growth in floodplains with flood damage prevention ordinances, its building codes, and the Safety Element of the municipal General Plans.
8.3 MITIGATION OPPORTUNITIES
Table 8-13 presents a range of potential opportunities considered by the Planning Partnership for mitigating the flood hazard.
Table 8-13. Potential Opportunities to Mitigate the Flood Hazard Community Scale Organizational Scale Government Scale
Manipulate the Hazard
• Clear storm drains and
culverts
• Use low-impact
development
techniques
• Clear storm drains and
culverts
• Use low-impact
development
techniques
• Maintain drainage systems
• Institute low-impact development techniques
on property
• Structural flood control, levees, channelization,
or revetments
• Stormwater management regulations and
master planning
• Acquire vacant land or promote open space
uses in developing watersheds to control
increases in runoff
Reduce Exposure and Vulnerability
• Locate outside of
hazard area
• Elevate utilities above
base flood elevation
• Use low-impact
development
techniques
• Raise structures above
base flood elevation
• Elevate items within
house above base
flood elevation
• Locate outside of
hazard area
• Use low-impact
development
techniques
• Build critical function
redundancy or retrofit
critical buildings
• Provide floodproofing
when new critical
infrastructure must be
located in floodplains
• Locate or relocate critical facilities outside of
hazard area
• Acquire or relocate identified repetitive loss
properties
• Promote open space uses in identified high
hazard areas via techniques such as planned
unit developments, easements, setbacks,
greenways, sensitive area tracks
• Adopt land development criteria such as
planned unit developments, density transfers,
clustering Institute low impact development
techniques on property
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Flood 8-24
Community Scale Organizational Scale Government Scale
• Build new homes
above base flood
elevation
• Flood-proof structures
• Acquire vacant land or promote open space
uses in developing watersheds to control
increases in runoff
• Harden infrastructure, bridge replacement
program
• Provide redundancy for critical functions and
infrastructure
• Adopt regulatory standards such as freeboard
standards, cumulative substantial
improvement or damage, lower substantial
damage threshold, compensatory storage, nonconversion deed restrictions • Stormwater management regulations and
master planning
• Adopt “no-adverse impact” floodplain
management policies that strive to not
increase the flood risk on downstream
communities
• Improve unpaved roads to reduce their
likelihood to fail due to flooding
Build Local Capacity
• Buy flood insurance
• Develop household
plan, such as retrofit
savings,
communication with
outside, 72 hour selfsufficiency during and
after an event
• Keep cash reserves for
reconstruction
• Support and
implement hazard
disclosure for sale of
property in risk zones
• Solicit cost-sharing
through partnerships
on projects with
multiple benefits
• Produce better hazard maps
• Provide technical information and guidance
• Enact tools to help manage development in
hazard areas (stronger controls, tax incentives,
and information)
• Incorporate retrofitting or replacement of
critical system elements in capital
improvement plan
• Develop strategy to take advantage of postdisaster opportunities • Warehouse critical infrastructure components
• Develop and adopt a continuity of operations
plan
• Consider participation in the Community
Rating System
• Maintain and collect data to define risks and
vulnerability
• Train emergency responders
• Create an elevation inventory of structures in
the floodplain
• Develop and implement a public information
strategy
• Charge a hazard mitigation fee
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Flood 8-25
Community Scale Organizational Scale Government Scale
• Integrate floodplain management policies into
other planning mechanisms within the
Planning Area.
• Consider impacts of climate change on the risk
associated with the flood hazard
• Consider the residual risk associated with
structural flood control in future land use
decisions
• Enforce National Flood Insurance Program
• Adopt a Stormwater Management Master Plan
Nature-based Opportunities
• Restore and reconnect floodplains that have been degraded by development and structural flood control • Use soft approaches for stream bank restoration and hardening • Set back levees on systems that rely on levee protection to allow the channel to meander, which reduces erosion and scour potential
• Preserve floodplain storage capacity by limiting or prohibiting the use of fill in the floodplain • Incorporated green infrastructure into stormwater management facilities • Protect and/or restore riparian buffers
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Heat Wave 9-1
9. HEAT WAVE
9.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.
9.1.1 Description of the Hazard
Defining the Hazard
In California, a heat wave, or extreme heat event, is defined as 3 days over 100 degrees Fahrenheit (° F) (FEMA National Risk Index, n.d.). Extreme heat overall is defined as temperatures that hover 10° F or more above the average high temperatures for a region for several days or weeks. Heat waves can lead to an increase in heat-related illnesses and deaths, worsen drought, and impact water supplies and other industries such as transportation, agriculture, and energy (California Office of Environmental Health Hazard Assessment, 2022).
Cause of the Hazard
Heat waves are usually a result of both high temperatures and high relative humidity. The higher the relative humidity or the more moisture in the air, the less likely that evaporation will take place. This becomes significant when high relative humidity is coupled with soaring temperatures, posing significant risk to human health. Anthropogenic climate change is fueling an increase in frequency of extreme heat days in California (California Office of Environmental Health Hazard Assessment, 2022).
The severity of heat waves can be amplified by the “urban heat island effect” which is the phenomena defined by the National Integrated Heat Health Information System in which cities experience more intense warming than their surrounding rural landscapes, particularly during the summer. This temperature difference occurs when cities’ unshaded roads and buildings absorb heat during the day and release this heat slowly (California Office of Environmental Health Hazard Assessment, 2022). As a result, highly developed urban areas can experience mid-afternoon temperatures that are 15° F to 20° F warmer than surrounding, vegetated areas (California Office of Environmental Health Hazard Assessment, 2022).
Summary of Potential Impacts
Heat waves have significant impacts on human health and infrastructure. Extreme heat is the primary weather-related cause of death in the United States. In a 10-year record of weather fatalities across the nation (2015-2024), excessive heat claimed more lives each year than floods, tornadoes, and hurricanes (NOAA, n.d.). According to the California Climate Adaptation Strategy, heat waves have claimed more lives in California than all other declared disaster events combined.
Heat-related illness includes a spectrum of illnesses ranging from heat cramps to severe heat exhaustion and life-threatening heat stroke Those who work outside are at risk for heat stroke or sun stroke, heat
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Heat Wave 9-2
exhaustion, fatigue, and dehydration (California Office of Environmental Health Hazard Assessment, 2022). Elevated nighttime temperatures are likely key ingredients in causing heat-related illness and mortality. Heat-related illness includes a spectrum of illnesses ranging from heat cramps to severe heat exhaustion and life-threatening heat stroke Those who work outside are at risk for heat stroke or sun stroke, heat exhaustion, fatigue, and dehydration (California Office of Environmental Health Hazard Assessment, 2022). Elevated nighttime temperatures are likely key ingredients in causing heat-related illness and mortality. Heat impacts infrastructure safety and agencies’ ability to provide timely and efficient services to their customers.
Cascading Hazard Impacts
Heat waves can lead to the cascading hazard of drought and wildfire, depending on the severity and length of the event. Existing drought and wildfire conditions can be severely exacerbated by extreme heat events, further drying out soil and vegetation and increasing electricity demand. These hazards are covered in Sections 6 and 0.
Extreme heat can also impact infrastructure and economies. Urban infrastructure is especially threatened by cascading effects of extreme heat stress on interdependent water, power, and transportation systems. High heat can deteriorate pavement, buckle railway tracks, and restrict aircraft operations. During hot weather, increased use of air conditioning and refrigeration increases electricity usage, thus straining the electrical grid (California Department of Water Resources, 2025).
9.1.2 Location
Extreme heat has not historically been a hazard of main concern for the Palos Verdes Peninsula. This is due to the Planning Area’s coastal location and exposure to cooling winds from the sea (National Oceanic and Atmospheric Administration, n.d.). However, future projections indicate that the Planning Area could experience more frequent and intense episodes of extreme heat, which will impact the entire Planning Area, especially those without air conditioning.
9.1.3 Extent
Heat emergencies are often slow to develop and usually hurt vulnerable populations and already aging and damaged infrastructure. It could take several days of oppressive heat for a heat wave to have a significant or quantifiable impact in the Planning Area.
Measuring Intensity
Heat wave extent can be defined by local record highs and the NWS Heat Index. The NOAA and NWS devised the “Heat Index” chart shown on Figure 9-1, which uses air temperature and humidity to determine the heat index or apparent temperature. In addition, information regarding the likelihood of health dangers by temperature range is presented (National Weather Service & National Oceanic and Atmospheric Administration, 2024).
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Heat Wave 9-3
Source: NWS Heat Index (Heat Index)
Figure 9-1. NWS Heat Index
Warning Time
The NWS is producing experimental forecasts called HeatRisk to assess the heat risk to local thresholds in California, Nevada, Utah, and Arizona. The NWS issues excessive heat watches, excessive heat warnings, and heat advisories to warn of an extreme heat event (a “heat wave”) within 36 hours of the predicted event (National Weather Service, 2023).
The NWS will use the HeatRisk Index (Table 9-1) to determine if an excessive heat watch/warning or heat advisory is warranted. The NWS issues the following types of heat-related advisories:
• Heat Advisory—HeatRisk Index category is on the orange/red that includes the Level 2 and Level 3 thresholds
• Excessive Heat Watch/Warning—HeatRisk Index category is on the red/magenta that includes the Level 3 and Level 4 thresholds
An Excessive Heat Watch is a way to give the public and emergency officials a warning that extreme temperatures are expected. If high temperatures remain forecasted for 24 to 28 hours, the excessive heat watch will be upgraded to an excessive heat warning (National Weather Service, 2023).
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Heat Wave 9-4
Table 9-1. NWS HeatRisk Index
Category Risk of Heat-Related Impacts
Green 0 Little to no risk from expected heat.
Yellow 1 Minor - This level of heat affects primarily those individuals extremely sensitive to heat, especially when outdoors without effective cooling and/or adequate hydration.
Orange 2
Moderate - This level of heat affects most individuals sensitive to heat, especially those without effective cooling and/or adequate hydration. Impacts possible in some health systems and in heat-sensitive industries.
Red 3 Major - This level of heat affects anyone without effective cooling and/or adequate hydration.
Impacts likely in some health systems, heat-sensitive industries and infrastructure.
Magenta 4
Extreme - This level of rare and/or long-duration extreme heat with little to no overnight relief affects anyone without effective cooling and/or adequate hydration. Impacts likely in most health systems, heat-sensitive industries and infrastructure.
Source: NWS HeatRisk ( NWS HeatRisk)
Worst-Case Scenario
The worst-case scenario for an extreme heat wave in the Palos Verdes Peninsula would be a heat wave lasting longer than 3 days with an Excessive Heat Warning Level 4. This heat wave would have temperatures near or above 100° F with no overnight cooling, especially in densely developed areas. A heat wave of this magnitude would impact a broad swath of the population, including those with air conditioning.
Prolonged heat would put a strain on the Planning Area’s energy grid, health system, and cause widespread damage to infrastructure. A prolonged heat wave can occur with cascading hazards, most importantly drought and wildfire. California’s current projections indicate an increase in extreme heat days, which increase the likelihood of drought conditions in the Planning Area. Rising temperatures and a lack of precipitation can lead to ideal conditions for wildfires, which could impact all residents in the Planning Area. The destruction caused by these wildfires, including denuding vegetation and burn scars, increases the risk of mudslides and flooding when heavy rain occurs (NOAA NCEI, 2021).
9.1.4 Previous Occurrences
The following sections provide a review of previous heat wave occurrences in the Planning Area.
Declarations
Historically, FEMA has denied requests and subsequent appeals for federal disaster declarations related to extreme heat events, stating that the cascading impacts of heat-related events, such as wildfires, cause the damage for which states seek assistance (Congressional Research Service, 2024).
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Heat Wave 9-5
Federal Declarations
There have been no federal declarations for heat waves for Los Angeles County (FEMA, 2025).This is because of limitations in the Stafford Act, which allocates funds to states for natural disasters. While no recorded heat wave has occurred in the Planning Area since 2019, members of Congress have introduced legislation to include extreme heat in the Stafford Act (Congressional Research Service, 2024).
State Proclamations
There have been no state proclamations related to heat waves for Los Angeles County (Cal OES, 2025).
USDA Declarations
There have been no USDA declarations related to heat waves for Los Angeles County (U.S. Department of Agriculture, 2025).
Summary of Significant Events
Los Angeles County has 13 events listed in their record of extreme heat history. Of this, the all-time record occurred in 1955 when Los Angeles hit 110° F on September 1 of that year. The most recent extreme heat events are summarized below:
• July/August 2023 – between July 11 and August 2, daytime temperatures only dipped below 90° F on 1 day.
• August 2023 – Two multi-day heat events occurred with temperatures over 90° F, peaking at 102° F.
• July 2024 – A weeklong extreme heat event occurred with temperatures between 90° F to 97° F. • September 2024 – An extreme heat
wave impacted southern California
the first week of the month, with
daytime temperatures 10° to 20°
above normal for that time of year.
Persistent triple-digit temperatures
drove a spike in emergency room
visits for heat-related illnesses.
Three fires burning in the eastern
part of Los Angeles County exploded
in intensity during this time period,
impacting communities with smoke
and short-notice evacuations
(NOAA, 2024).
• August/September 2025 – Countywide heat advisories, warm nights, and regional wildfire and air‑quality
impacts.
Figure 9-2. September 2024 Extreme Heat Map
Source: (NOAA , 2024)
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Heat Wave 9-6
Recent Events
The NOAA NCEI Storm Events Database have not reported any excessive or extreme heat events impacting the Planning Area’s forecast zones from 2019 to 2025 (NOAA NCEI, 2025).
9.1.5 Future Conditions
Future hazard conditions, including frequency and severity of future events, are discussed in the sections below.
Probability
Extreme heat has become more frequent in California since 1950, especially at night. Heat waves – two or more consecutive heat events – vary from year to year but have become more frequent in the past decade (California Office of Environmental Health Hazard Assessment, 2022).
Climate Change
Projected warming temperatures will influence runoff, evaporation, and evapotranspiration, as well as drought and overall ecological health in the region. This includes longer growing seasons, shifts in vegetative populations, and invasive species encroachment.
Data projections from Cal-Adapt, a tool provided by the California Energy Commission, were utilized to obtain localized climate change projections as it relates to the hazard of extreme temperature (Cal Adapt, 2025). Data suggests that climatic changes may intensify the severity and frequency of extreme heat events in the Planning Area. The increase in average surface temperatures can also lead to more intense heat waves that can be exacerbated in the Planning Area.
According to the California HPI: Extreme Heat Edition, the Palos Verdes Peninsula is expected to experience 10.2 days over 90° F during years 2035 to 2064. While this number is lower than much of California, putting it at a Healthy Places Index rating of 98/100, this figure is expected to increase during years 2077 to 2099 (California Healthy Places Index, 2022).
Potential Future Impacts
Grid vulnerabilities to potential future heat waves described by climate change projections were assessed throughout Los Angeles County. Heat waves have posed serious challenges to power infrastructure in Southern California, including a major blackout in 2011 and emergency curtailment in 2014, and understanding how future temperature change might impact the power system is critically important for its continued reliable operation. Potential increases in peak demand, resource adequacy requirements, and component over-loadings were forecast for ranges of scenarios from 2021 to 2060.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Heat Wave 9-7
9.2 VULNERABILITY ASSESSMENT
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(ii) The plan must include a description of the jurisdiction’s vulnerability to the hazards of concern and include an overall summary of the hazard’s impact on the community. The impacts need to include the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the hazard areas, and estimate of potential dollar losses to vulnerable structures, and a description of land uses and development trends.
9.2.1 Summary of Vulnerability
The entire Planning Area is exposed to the extreme heat hazard, so an event has the potential to affect the entire population. Extreme heat generally does not impact buildings, but all buildings in the Planning Area will have an increased energy demand for cooling. All of the Planning Area’s identified critical facilities and the entire environment of the Planning Area are vulnerable to the extreme heat hazard.
9.2.2 Impact on Life, Health, and Safety
Extreme heat can cause illness such as heat exhaustion and heat stroke, and can induce or exacerbate illnesses related to cardiovascular, respiratory, renal, and mental health (UCLA Luskin Center for Innovation & Public Health Alliance of Southern California, 2025). According to the California Healthy Places Index: Extreme Heat Edition tool, the Palos Verdes Peninsula is projected to experience 10.2 days per year with temperatures exceeding 90° F between 2035 and 2064. This is significantly lower than the statewide median value of 79.9 days (California Healthy Places Index, 2022).
Equity Priority Communities
Equity Priority Community populations that may be more at risk from heat waves include older individuals and those with access and functional needs. Power outages triggered by overburdened electrical grids can be life threatening to those dependent on electricity for medical devices. Members of these communities who do not have access to air conditioning would lack nighttime relief from the heat, elevating their risk of health complications.
9.2.3 Impact on General Building Stock
Extreme heat events can significantly impact the built environment by causing infrastructure damage, increasing energy demand, exacerbating urban heat island effects, and posing health risks to residents and workers, necessitating adaptation strategies like green infrastructure and heat-resilient design. All of the general building stock within the Palos Verdes Peninsula is considered to be exposed to the extreme heat hazard with varying degrees of vulnerability based on the age and condition of the structures.
9.2.4 Impact on Community Lifelines
Extreme heat events can severely impact community lifelines by straining infrastructure, increasing energy demand, and disrupting essential services like healthcare, transportation, and food security, potentially leading to power outages, heat-related illnesses, and economic damage.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Heat Wave 9-8
9.2.5 Impact on the Economy
The economic and societal consequences of extreme heat are pervasive. Impacts encompass reductions in gross domestic product, as workers and infrastructure systems become less productive, as well as wider detrimental effects on well-being, as healthcare outcomes worsen, and people are unable to access outdoor space. Impacts include transitory ones, from people enduring uncomfortable conditions and workers taking sick leave, and enduring losses, for example, due to interruptions to education or property damage from wildfires which can be more severe due to extreme heat’s effect on the environment. Tourism and other leisure activities are also affected as temperatures rise, making walking, shopping, and sightseeing uncomfortable and potentially dangerous.
According to the Atlantic Council’s Adrienne Arsht Rockefeller Foundation Resilience Center, extreme heat-related labor productivity losses already affect all regions and sectors of the U.S. economy. Under baseline climate conditions, the United States could lose on average approximately $100 billion annually from heat-induced lost labor productivity.
9.2.6 Impact on Historic and Cultural Resources
Extreme heat events pose significant threats to historic and cultural resources, leading to accelerated deterioration of materials, damage to structures and artifacts, and disruption of ecosystems around these sites.
9.2.7 Impact on Ecosystems and Natural Resources
Rising temperatures affect all types of ecosystems through shifts in species distribution and population structure and increase the risk of species extinction. These changes can impact ecosystem services, such as carbon storage, and affect crop production. Higher temperatures also naturally increase the risk of arid conditions and droughts.
9.2.8 Change in Vulnerability Since the Prior Planning Area HMPs Extreme heat vulnerability may be increasing slightly, not due to population growth, but due to climate change and the aging population of the Palos Verdes Peninsula.
9.3 MITIGATION OPPORTUNITIES
Table 9-2 presents a range of potential opportunities considered by the Planning Partnership for mitigating the extreme heat hazard.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Heat Wave 9-9
Table 9-2. Potential Opportunities to Mitigate the Heat Wave Hazard Community Scale Organizational Scale Government Scale
Manipulate the Hazard
• Plant trees to create shade in
urban areas
• Remove concrete and other
hard surfaces and replace
them with native vegetation
• Plant trees in urban areas
experience urban heat island
effects or with below average
tree canopy coverage
• Remove concrete and other
hard surfaces and replace
them with native vegetation
• Plant trees in urban areas
experience urban heat island
effects or with below average
tree canopy coverage
• Remove concrete and other
hard surfaces and replace
them with native vegetation
Reduce Exposure and Vulnerability
• Insulate structures to provide
greater thermal efficiency
• Provide redundant power
sources
• Install air conditioning
• Relocate critical infrastructure
underground
• Provide cooling centers for
employees
• Install “cool roofs” and “green
roofs”
• Relocate critical infrastructure
underground
• Trim trees away from power
lines
• Install “cool roofs” and “green
roofs”
• Establish and promote
accessible cooling centers in
the community
• Use the best available
technology to enhance the
warning systems for extreme
heat events
Build Local Capacity
• Promote 72-hour selfsufficiency
• Obtain a NOAA weather radio
• Obtain an emergency
generator
• Provide safety training and
resources for employees that
work primarily outside and at
field locations
• Create redundancy in power
supply
• Equip facilities with a NOAA
weather radio
• Equip vital facilities with
emergency backup power
• Enhance public awareness and
outreach to address actions to
take during extreme heat
events
• Coordinate severe weather
warning capabilities and the
dissemination of warning
among agencies with the
highest degree of capability
• Modify land use and
environmental regulations to
support vegetation
management activities that
improve reliability in utility
corridors
• Modify landscape and other
ordinances to encourage
appropriate planting near
overhead power, cable, and
phone lines
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Heat Wave 9-10
Community Scale Organizational Scale Government Scale
• Provide NOAA weather radios
to the public
• Review and update heat
response plan to account for
climate change projections
• Promote programs that
support community-scale
microgrids
• Evaluate and revise building
codes to address and mitigate
extreme heat impacts on
residents
Nature-based Opportunities
• Manage invasive species that thrive in warmer temperatures • Incorporate nature-based heat-reduction measures with plantings in green spaces, trail areas, and community parks
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Landslide 10-1
10. LANDSLIDE
10.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.
10.1.1 Description of the Hazard
Defining the Hazard
A landslide is a mass of rock, earth or debris moving down a slope. Landslides may be minor or large and can move at slow to very high speeds. Mudslides are rivers of rock, earth, organic matter, and other soil materials saturated with water. They develop in the soil overlying bedrock on sloping surfaces when water rapidly accumulates in the ground, such as during heavy rainfall.
Mass Movement
Mass movement is the movement of rock and soil down slope under the influence of gravity. Landslides are the most commonly recognized type of mass movement. Other common mass movement types include the following:
• Mudflows, sometimes referred to as mudslides, mudflows, lahars, or debris avalanches, are fastmoving rivers of rock, earth, and other debris saturated with water. They develop when water rapidly accumulates in the ground, such as heavy rainfall or rapid snowmelt, changing the soil into a flowing river of mud or “slurry.”
• Slurry can flow rapidly down slopes or through channels and can strike with little or no warning at avalanche speeds. Slurry can travel several miles from its source, growing larger as it picks up trees, cars, and other materials along the way. As the flows reach flatter ground, the mudflow spreads over a broad area where it can accumulate in thick deposits. • Creep is the imperceptibly slow downward movement of slope forming rock or soil that can be accelerated during wet weather events or earthquakes. This slow-moving landslide is often only noticed through crooked trees and disturbed structures. • Coastal bluff erosion is the collapse of coastal bluffs due to undercutting erosive forces of wave action.
• Rock falls are rapid movements of bedrock, which result in bouncing or rolling. • Rock topple is a section or block of rock that rotates or tilts before falling to the slope below. • Block slides are movements of soil or rock along a distinct surface of rupture, which separates the slide material from the more stable underlying material. • Earth flows is the mass movement of fine-grained sediments that flow downhill and typically form a fan structure.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Landslide 10-2
Deep-Seated Landslides
Deep-seated landslides (greater than 10 to 15 feet deep or below the rooting depth of vegetation) are typically triggered by prolonged ground saturation caused by deep infiltration of rainfall or other longterm hydrologic processes, earthquake shaking, or a combination of both rainfall and seismic activity.
Some deep-seated landslides move very slowly, though others can move quickly and with little notice (California Governor's Office of Emergency Services, 2024).
Shallow Landslides
Shallow landslides typically originate in uppermost soil or rock layers (greater than 10 feet deep or in the rooting zone of vegetation) on steep slopes and often form slumps or fast-moving earth and debris flows (USGS, 2025). Shallow landslides can similarly be triggered by sustained rainfall or saturated soils.
Land Subsidence
Land subsidence is the gradual lowering of land-surface elevation due to changes in the soil or sediment.
In California, subsidence has been documented for over a century and is a growing issue that impacts water infrastructure and communities (California Department of Water Resources, 2025).
Cause of the Hazard
Both natural and human-induced changes in the environment can trigger landslides and other forms of mass movement. Landslides are caused by a combination of geological and climate conditions and the influence of urbanization. They can be initiated by storms, earthquakes, fires, or human modification of the land or infrastructure. Vulnerable natural conditions are affected by human development and the infrastructure that supports it. The following factors can contribute to slide formation:
• Change in slope of the terrain
• Increased load on the land
• Shocks and vibrations
• Change in water content
• Groundwater movement (watershed)
• Weathering of rocks
• Removing or changing the type of vegetation covering slopes Areas that are generally prone to landslide hazards include previous landslide areas (i.e. active or inactive ancient landslides), the bases of steep slopes, the bases of drainage channels, and developed hillsides where leach field septic systems are used. Areas that are typically considered safe from landslides include areas that have not moved in the past, relatively flat-lying areas away from sudden changes in slope, and areas at the top or along ridges set back from the tops of slopes.
While small landslides are frequently a result of human activity, the largest landslides are often naturally occurring phenomena with little or no human contribution. The sites of large landslides are typically areas of previous landslide movement that are periodically reactivated by significant precipitation or seismic events.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Landslide 10-3
Summary of Potential Impacts
Landslides in hillside terrain can pose serious hazard to downslope property and structures. They can disrupt roadways and other infrastructure lifelines, destroy private property, and cause flooding, bank erosion, and rapid channel migration. A slide can move rapidly down slopes or through channels and can strike with little or no warning. It can travel miles from its source, growing as it descends, picking up trees, boulders, cars, and anything else in its path. Although slides behave as fluids, they convey many times the hydraulic force of water due to the mass of material they carry.
Despite their destructive potential, landslides can serve beneficial functions to the natural environment.
They supply sediment and large wood to the channel network and can contribute to complexity and dynamic channel behavior critical for aquatic and riparian ecological diversity.
Cascading Hazard Impacts
Landslides that block rivers or streams can form unstable natural dams, trapping water and creating temporary lakes. These impoundments pose a serious risk of sudden failure, which can create destructive flash flooding downstream. Saturated soils from these events can likely destabilize nearby slopes, triggering additional landslides and cause cascading effects such as damaged infrastructure and roads, isolating rural communities, disrupting emergency services, and contaminating water sources.
10.1.2 Location
The analysis assumed, in general, that susceptibility to deep-seated landslides is low on very low slopes in all rock materials and increases with slope steepness and in weak rocks and soils. The analysis also factored in locations of past landslides. Figure 10-1 shows Californian Geological Survey (CGS) historic landslide occurrences for the Planning Area.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Landslide 10-4
Figure 10-1. Historic Landslide Occurrences
10.1.3 Extent
Measuring Intensity
Landslides are typically a function of soil type and steepness of slope. Soil type is a key indicator for landslide potential and is used by geologists and geotechnical engineers to determine soil stability for construction standards. Figure 10-2 presents the steepness of slope and Figure 10-3 presents the soils map for the Planning Area. In general, landslide hazard areas are where the land has characteristics that contribute to the risk of the downhill movement of material, such as the following:
• A slope greater than 33 percent
• Post-wildfire areas
• A history of landslide activity or movement during the last 10,000 years • Stream or wave activity, which has caused erosion, undercut a bank or cut into a bank to cause the surrounding land to be unstable
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• The presence of an alluvial fan, indicating vulnerability to the flow of debris or sediments • The presence of impermeable soils, such as silt or clay, mixed with granular soils, such as sand or gravel
The best predictor of where slides might occur is the location of past movements. Past landslides can be recognized by their distinctive topographic shapes, which can remain in place for thousands of years.
Most landslides recognizable in this fashion range from a few acres to several square miles. Most show no evidence of recent movement and are not currently active. A small proportion of them may become active in any given year, with movements concentrated within all or part of the landslide masses or around their edges. The recognition of ancient dormant landslide sites is important in the identification of areas susceptible to flows and slides because they can be reactivated by earthquakes or by exceptionally wet weather. Also, because they consist of broken materials and frequently involve disruption of groundwater flow, these dormant sites are vulnerable to construction-triggered sliding.
Figure 10-2. Steep Slope Map
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Figure 10-3. Soils Map
Warning Time
Landslides can occur suddenly or slowly. The velocity of slide may range from a slow creep of inches per year to many feet per second, depending on slope angle, material, and water content. Generally accepted warning signs for landslide activity include the following:
• Springs, seeps, or saturated ground in areas that have not typically been wet before • New cracks or unusual bulges in the ground, street pavements, or sidewalks • Soil moving away from foundations
• Ancillary structures such as decks and patios tilting or moving relative to the main house • Tilting or cracking of concrete floors and foundations (doors and windows are difficult to move) • Broken waterlines and other underground utilities
• Leaning telephone poles, trees, retaining walls or fences • Offset fence lines
• Sunken or down-dropped road beds
• Rapid increase in creek water levels, possibly accompanied by increased turbidity (soil content)
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• Sudden decrease in creek water levels though rain is still falling or just recently stopped • Sticking doors and windows and visible open spaces indicating frames out of plumb • A faint rumbling sound that increases in volume as the landslide nears • Unusual sounds, such as trees cracking or boulders knocking together Some methods used to monitor landslides can provide an idea of the type of slide and the amount of time prior to failure. Assessing the geology, vegetation, and amount of predicted precipitation for an area can help in predictions of what areas are at risk during general time periods. Currently, there is no practical warning system for individual landslides. The standard operating procedure is to monitor situations on a case-by-case basis and respond when an event occurs.
Worst-Case Scenario
The worst-case scenario for landslide hazards in the Planning Area would generally correspond to a severe storm with heavy rain that caused flooding in an area that had been burned by fire. Landslides are more likely during the late winter when the water table is high. After heavy rains, typically between November and March, soils become saturated with water. As water seeps downward through upper soils, it can weaken and destabilize the slope, especially in areas with weak, clay-rich soils. A short intense storm could cause saturated soil to move, resulting in landslides. As rainfall continues, the groundwater table rises, adding to the weakening of the slope. Gravity, poor drainage, a rising groundwater table, and poor soil exacerbate hazardous conditions.
10.1.4 Previous Occurrences
The following sections provide a review of previous landslide/mass movement occurrences in the Palos Verdes Peninsula.
Declarations
Federal Declarations
Between 2019 and 2025, the Planning Area experienced five major disaster (DR) or emergency declarations (EM) related to landslide/mass movement hazard.
Table 10-1. Federal Landslide Disaster Declarations
Disaster Number Incident Period Declaration Date Description DR-4683-CA December 27, 2022 – January
31, 2023
January 14, 2023 California Severe Winter Storms,
Flooding, Landslides, and
Mudslides
EM-3591-CA January 8 – January 31, 2023 January 9, 2023 California Severe Winter Storms, Flooding, and Mudslides
DR-4699-CA February 21 – July 10, 2023 April 3, 2023 Severe Winter Storms, StraightLine Winds, Flooding, Landslides, and Mudslides
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Disaster Number Incident Period Declaration Date Description EM-3592-CA March 9 – July 10, 2023 March 10, 2023 Severe Winter Storms, Flooding, Landslides, and Mudslides
DR-4769-CA January 31– February 9, 2024 April 13, 2024 Severe Winter Storms, Tornadoes, Flooding,
Landslides, and Mudslide
Source: (FEMA, 2025)
State Proclamations
Between 2019 and 2025, California declared one disaster related to landslide/mass movement in the Planning Area. This declaration was related to utility shutoffs caused by the winter storm induced landslides that began in 2023 and are still ongoing.
Table 10-2. State Landslide Disaster Declarations
Disaster Number Declaration Date Description
N/A September 3, 2024 Rancho Palos Verdes Land Movement Impacts to Utility Services
Source: (Cal OES, 2025)
USDA Declarations
Between 2019 and 2025, the USDA declared no disasters related to landslide/mass movement in the Planning Area County (U.S. Department of Agriculture, 2025).
Summary of Significant Events
The Palos Verdes Peninsula has a long history of landslides, most notably the massive, ancient Greater Portuguese Bend Landslide Complex, first significantly activated by road construction in 1956, causing continuous movement and damaging hundreds of homes over decades.
A summary of significant events affecting the Planning Area is detailed below. 1956 Portuguese Bend Landslide
The largest landslide to occur in the Planning Area was the activation of the Portuguese Bend Landslide a subslide of the Greater Portuguese Bend Landslide Complex. The slide area encompasses approximately 270 acres. The weight of the moving material is estimated to be about 60 million tons, with a maximum thickness calculated to be 250 feet. The slide began in August 1956 in conjunction with a Los Angeles County roadway project to extend Crenshaw Boulevard from Crest Road to Palos Verdes Drive South. Initially, movement was 3 to 4 inches per day, quickly slowing to 1 inch per day a month later.
The reactivation of this ancient landslide resulted in the loss of 134 residential dwellings, which were damaged beyond repair and razed. Relocation to safer ground saved a few homes (Reiter, 1984). The slide also destroyed the Portuguese Bend Beach Club a private recreational facility that included a large clubhouse, saltwater pool, boating pier, tennis courts, and volleyball courts. Between 1962 and 1970, movement slowed to 1/2 inch per day (Reiter, 1984).
The Portuguese Bend Landslide movement can range from 12 inches per year to 12 inches per week, depending on the amount of rainfall the previous season. Nearly all of the remaining homes in the active
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Landslide 10-9
slide area have been placed on elevated or so-called “floating” foundations that can be adjusted as the earth continues to slowly move and buckle beneath the homes. Refer to the summarized impacts of the 2023-2024 Atmospheric River Event for significant events impacting the Portuguese Bend Landslide. 1974 Abalone Cove Landslide
Activation of the 80-acre Abalone Cove Landslide a subslide of the Greater Portuguese Bend Landslide Complex was first noted at the shoreline in February 1974. Slow movement continued between the shoreline and Palos Verdes Drive South until 1978 but only impacted vacant land. In late April or early May 1978, following one of the rainiest seasons on record (29.61 inches fell during 1977-78 compared to an average annual rainfall of 11.38 inches), the slide began to accelerate, and cracking was seen in the roadway. The slide reached its maximum inland extent in February 1980, following 7.75 inches of rain during a 10-day period. Because the Abalone Cove Landslide started along the coastline and progressed landward, it was not triggered by drag from the abutting Portuguese Bend Landslide. The major factors attributed to reactivation of the slide appear to be rainfall and rising groundwater levels (Reiter, 1984). Although no homes were destroyed as a result of this slide, the visitor’s center at the landmark Wayfarers Chapel was severely damaged and closed to the public in 1982. All but a small portion of the original structure was razed in 1995 and a new visitors center was constructed west of the slide scarp in 1999.
As a result of the Abalone Cove Landslide, the Abalone Cove Landslide Abatement District (ACLAD) was established as a geologic hazard abatement district. The ACLAD continues its mission of abating the Abalone Cove Landslide through the management of dewatering wells to remove ground water that fuels the Abalone Cove Landslide (RPV, 2025).
1979 Klondike Canyon Landslide
Activation of the Klondike Canyon Landslide, a subslide of the Greater Portuguese Bend Landslide Complex occurred in 1979 adjacent to the coastline and to the east of the much larger Portuguese Bend Landslide. Like the Portuguese Bend and the Abalone Cove Landslides, Woodring published the location of the ancient “Beach Club Landslide” in 1946. However, by that time, both Yacht Harbor Drive (in 1927) and Palos Verdes Drive South (in 1937) had been constructed across this landslide. Development of the two roadways was followed in the late 1940’s by the construction of the Portuguese Bend Club and grading for the Seaview tract landward of Palos Verdes Drive South was completed in late 1956.
Following record-breaking rainfall in 1977-1978, the first indications of movement of the Klondike Canyon Landslide were noted in September 1979 at the intersection of Dauntless Drive and Exultant Drive in the Seaview tract. Heavy rainfall continued during 1979-1980 and 1982-1983, accelerating land movement, which damaged local roads and eventually destroyed one home in the Seaview tract.
In 1981, the Klondike Canyon Landslide Geologic Abatement District (KCLAD) was established as a California State Geological Hazard Abatement District for the 50 acre Klondike Canyon Landslide. KCLAD manages dewatering wells to lower the ground water table within the slide mass (RPV, 2025). The dewatering efforts have been successful in stabilizing the area and additional landslide abatement efforts have continued since that time, such as drainage improvements in Klondike Canyon and the installation of a private sewer system in the Portuguese Bend Beach Club.
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1980 Flying Triangle Landslide
The Flying Triangle landslide, a subslide of the Greater Portuguese Bend Landslide Complex, occupies an area of approximately 70 acres on the south side of the crest of the Palos Verdes Hills overlooking Portuguese Bend. Movement was first formally observed in March 1980, though displacement may have begun as early as 1974. The landslide represents the reactivation of a relatively large, complex compound ancient landslide of probable Pleistocene age that is unrelated to the main Portuguese Bend landslide.
The reactivation is directly attributed to a period of unusually heavy precipitation during the early 1980s.
As ground movement intensified, residential structures within the affected area were threatened; some homes were demolished, while others were retrofitted and supported on steel I-beam systems to accommodate continued movement. During this period, gas and water utilities were relocated above ground to reduce the risk of rupture and to maintain service continuity. 1997 Indian Peak Road
The 1997 Indian Peak Road caused a considerable amount of property damage. In March 1997, two office buildings located in the 900 block of Indian Peak Road in Rolling Hills Estates toppled and slid down a hillside, causing damage to another building near Deep Valley Drive. 1999 Ocean Trails Golf Course
In June 1999, just 1 week before its scheduled grand opening, the entire 18th fairway of the former Ocean Trails Golf Course in Rancho Palos Verdes collapsed into the ocean, resulting in the loss of approximately 12 acres of land.
2005 Poppy Trail Landslide
On March 5, 2005, a 300-foot-long portion of a steep hillside at No. 1 Poppy Trail Road in Rolling Hills sheared off and slid downhill, terminating just below the roadway easement for Poppy Trail Road. The slide buried a portion of the road, temporarily eliminating ingress and egress for nine residential lots. In response, the affected area was stabilized through emergency grading and other temporary protective measures to reduce erosion and further movement. The slide mass was subsequently reshaped, the roadway was rebuilt, and full ingress and egress were restored to the impacted homes. 2022-2023 Peartree Lane Landslide
The Peartree Lane Slope Failure in Rolling Hills Estates became apparent on July 8, 2023. The landslide moved laterally up to 45 feet into the adjacent canyon and destroyed and/or red-tagged five multi-family townhome structures containing 12 units. An additional five units were yellow-tagged due to utility damage (Rolling Hills Estates, n.d.). The City of Rolling Hills Estates and County of Los Angeles retained a consultant to investigate the Peartree Lane landslide event. The results of the investigation determined that record rainfall from atmospheric rivers in winter 2022–2023 caused a new landslide in a developed area, with precipitation levels not seen since the 1980s and early 2000s. This event was determined to be a new failure, not a reactivation of a previous slide. Secondary factors included the reduction in vegetation due to residential development and localized surficial failures on the steep slope.
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Landslide 10-11
As a result of the Peartree Lane Landslide, Rolling Hills Estates City Council declared a local emergency on January 11, 2023.
2023-2024 Atmospheric River Event
The atmospheric river event that occurred in
the winter of 2023-2024 caused land
movement in the fall 2023 and early 2024.
Flooding resulted in saturated soils and
accelerated the Greater Portuguese Bend
Landslide Complex including the subslides,
impacting areas like Abalone Cove and
Klondike Canyon. It also activated the deeper
Altamira Landslide that encompasses the
Portuguese Bend Landslide, the Abalone
Cove Landslide, the Klondike Canyon
Landslide, and the Beach Club Landslide.
Analysis completed by NASA’s Jet
Propulsion Laboratory determined that,
during a four-week period in the fall of 2024,
land in the residential area slid toward the
ocean by as much as 4 inches
(10 centimeters) per week (NASA, 2025).
The motion accelerated, and the active area
expanded following record-breaking rainfall
in Southern California in 2023 and heavy
precipitation in early 2024 (Jet Propulsion
Laboratory , 2025).
Figure 10-4 presents a public engagement
post by NASA, with the visualization
characterizing the speed and direction of the landslide. The darkest reds indicating the highest speeds of earthen movement with the arrows represent the direction of horizontal motion.
Recent Events
The California Department of Conservation reports California landslides in an interactive map built on data provided by government agencies, media, and citizen scientists. Table 10-3 summarizes these events in addition to recent landslide events impacting the Planning Area.
Table 10-3. Recent Landslide Events
Disaster Date Location Description
December 9, 2022 Coastal bluff collapse
impacting Rat Beach in
Palos Verdes Estates.
A significant landslide in December 2022 in Palos Verdes Estates resulted in a massive cliff collapse that nearly destroyed a lifeguard tower and pushed a maintenance truck.
The incident, which occurred along the coast near Rosita Figure 10-4. Fall 2024 Motion of Landslides on the Palos Verdes Peninsula
Source: (Jet Propulsion Laboratory , 2025)
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Disaster Date Location Description
Place, led to immediate, indefinite closure of the beach due to dangerous, ongoing instability.
Following the initial slide, a second, smaller slide occurred within hours. Geologists warned of further instability, leading to the closure of the beach from the southern part of Rat Beach to the northern part of Torrance Beach
February 1, 2024 North of Palos Verdes
Drive across from
entrance to parking lot
for Pelican Cover Park in
the City of Rancho Palos
Verdes.
Mud and debris deposited on eastbound and westbound
lanes
September 27,
2025
Coastal bluff off
Marguerite Drive near
Palos Verdes Drive West
in the City of Rancho
Palos Verdes.
According to the Los Angeles County Fire Department,
approximately 300-400 linear feet of the slope sloughed off, dropping approximately 50-60 feet toward the
coastline. There was no reported damage to public property, no injuries and no structural damage to the four homes
affected. This landslide is not related to the Greater
Portuguese Bend Landslide.
Source: (CA Department of Conservation, 2025)
10.1.5 Future Conditions
Future hazard conditions, including frequency and severity of future events, as discussed in the sections below.
Probability
Mass movements are often triggered by other natural hazards such as earthquakes, heavy rain, floods, or wildfires, so their frequency is often related to the frequency of the precipitating hazards. Most weather-induced landslides occur in the winter after the water table has risen, but may also occur months following a wet season. Landslides that result from earthquakes can occur at any time.
Climate Change
Climate change may impact storm patterns, increasing the probability of more frequent, intense storms with varying duration. Warming temperatures also could increase the occurrence and duration of droughts, which would increase the probability of wildfire, reducing the vegetation that helps to support steep slopes. Each these factors would increase the probability of landslides.
Potential Future Impacts
According to the California Department of Finance, the population of the greater Los Angeles County region is expected to increase over the next 45 years. Within the past 5 years, the population of the Palos Verdes Peninsula region has gradually declined. The Planning Area has limited potential for expansion through annexation, as it is surrounded by other incorporated cities and is for the most part built out.
As a result, continued growth would occur through redevelopment rather than outward expansion.
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10.2 VULNERABILITY ASSESSMENT
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(ii) The plan must include a description of the jurisdiction’s vulnerability to the hazards of concern and include an overall summary of the hazard’s impact on the community. The impacts need to include the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the hazard areas, and estimate of potential dollar losses to vulnerable structures, and a description of land uses and development trends.
10.2.1 Summary of Vulnerability
Summary findings of the risk assessment for landslide are shown below. Landslide susceptibility and vulnerability are defined by ten levels of severity, with one being the least susceptible and ten being the most susceptible. Please refer to Chapter 5. Risk Assessment Methodology and Tools for the detailed methodology.
10.2.2 Impact on Life, Health, and Safety
All people exposed to the landslide hazard are potentially vulnerable.
Equity Priority Communities
Vulnerable populations may experience greater impacts from landslides and other earth movements due to a financial inability to react or respond to these events. Vulnerable populations may reside in areas with only one means of ingress and egress, making them more vulnerable in the event of an evacuation.
Populations with access and functional needs as well as elderly populations are more vulnerable to the landslide hazards as they may not be able to evacuate quickly enough to avoid the impacts of a quickmoving landslide. The table below displays the number of vulnerable populations exposed to landslides.
Table 10-4. Vulnerable Populations Exposed to Landslides City
Total
Population
Demographic
Vulnerability
Population
Demographic
Vulnerability
% of Total
Population
Evacuation
Vulnerability
Population
Evacuation
Vulnerability
% of Total
Population
Palos Verdes
Estates
793 0 0.0% 0 0.0%
Rolling Hills
Estates
2,746 712 25.9% 438 15.9%
Rancho Palos
Verdes
322 322 100.0% 322 100.0%
Rolling Hills 276 79 28.7% 55 19.8%
Total 4,136 1,113 26.9% 814 19.7%
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10.2.3 Impact on General Building Stock
Property exposure and losses were estimated through a Level 3 approach using Hazus protocols for a user-defined analysis for the landslide hazard areas. Table 10-5 shows the estimates for the exposure and damage to structures and building contents with the percent of total replacement value. Table 10-6 summarizes the number of structures and type of occupancy in the landslide risk areas.
Table 10-5. Exposure Estimates for Landslide Susceptibility Areas City
No. of
Buildings
Exposed
Value of
Buildings
Exposed
Value of
Contents
Exposed
Total
Replacement
Cost Value
% of Total
Replacement
Value
Deep-Seated Landslide Loss
Palos Verdes Estates 310 $266,036,027 $133,822,473 $399,858,500 6.9% Rancho Palos Verdes 904 $575,221,081 $298,030,640 $873,251,721 6.8% Rolling Hills 135 $132,731,604 $66,365,802 $199,097,406 18.6% Rolling Hills Estates 103 $51,219,218 $26,879,904 $78,099,122 1.8% Total 1,452 $1,025,207,930 $525,098,819 $1,550,306,749 6.4% Table 10-6. Estimated Number of Buildings by Type, Located in the Landslide Susceptibility Areas City
ResidentialCommercialIndustrialAgricultureReligionGovernmentEducationTotal Palos Verdes Estates 305 5 0 0 0 0 0 310
Rancho Palos Verdes 891 8 0 1 3 0 1 904
Rolling Hills 135 0 0 0 0 0 0 135
Rolling Hills Estates 101 0 0 1 0 0 1 103
Total 1,432 13 0 2 3 0 2 1452
10.2.4 Impact on Community Lifelines
Many types of infrastructure are exposed to impacts from landslides, including transportation, water, sewer, gas, power, and communication infrastructure. Highly susceptible areas of the Palos Verdes Peninsula include roads and utility infrastructure, including dewatering systems.
Access to major roads is crucial to life and safety, including evacuations. Landslides can block egress and ingress on roads, causing isolation for neighborhoods, traffic problems and delays for public and private transportation. Many roads are also conduits for utilities that are vulnerable to landslides or land movement.
Power lines can be subjected to landslides. A landslide could trigger failure of soil underneath a power pole, causing it to collapse and rip down the lines which could lead to fires or wildfires in heavily vegetated areas. Power and communication failures due to landslides can create problems for vulnerable
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populations and businesses. Refer to Table 10-7 for a summary of community lifelines located in the Palos Verdes Peninsula that are in the moderate, high, and very high landslide hazard areas.
Landslide‑induced deformation frequently ruptures buried water and sewer lines, leading to service outages, localized flooding, loss of sanitation, and potential contamination of surrounding soils and coastal waters. These failures disrupt essential community lifelines and can further destabilize slopes by increasing groundwater infiltration and erosion when pressurized pipes break.
Damage curves were not established for the slow-moving landslide hazard. However, the damage and loss associated with damage to the utilities, roads, buildings, and other infrastructure; and emergency spending primarily on dewatering is more than $10 million per year. Refer to Appendix D for more information.
Table 10-7. Community Lifelines in Deep-Seated Landslide Hazard Areas City
CommunicationsEnergyFood, Hydration, ShelterHazardous MaterialsHealth and MedicalSafety and SecurityTransportationWater SystemsTotal Palos Verdes Estates TBD TBD TBD TBD TBD TBD TBD TBD TBD Rolling Hills Estates TBD TBD TBD TBD TBD TBD TBD TBD TBD Rancho Palos Verdes TBD TBD TBD TBD TBD TBD TBD TBD TBD Rolling Hills TBD TBD TBD TBD TBD TBD TBD TBD TBD
Total TBD TBD TBD TBD TBD TBD TBD TBD TBD
10.2.5 Impact on the Economy
Large landslides can cause economic impacts, including losses from severely damaged or destroyed property and infrastructure, and indirect impacts like disruptions to businesses and supply chains (i.e. delivery of goods and services). Homes in the Planning Area that have been red- or yellow-tagged may impact finances of local jurisdictions with the reduction of property taxes.
10.2.6 Impact on Historic and Cultural Resources
Landslides can cause damage to historical and cultural resources, ranging from structural damage to historic or protected buildings and monuments to the destruction of artifacts and archaeological sites, impacting cultural heritage.
10.2.7 Impact on Ecosystems and Natural Resources
Landslides can destroy natural resources valuable to the community. Landslides that fall into streams or the ocean may significantly impact fish and wildlife habitat, as well as affecting water quality. Hillsides that provide wildlife habitat can be lost due to landslides. Sensitive habitats may be located in areas prone to landslides, increasing the risk to biodiversity.
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Landslide movement has also forced the closure of key recreational amenities in the Planning Area, examples include beach access trails in the Abalone Cove Reserve and the full closure of Abalone Cove Beach and Sacred Cove Beach in 2024 due to unsafe ground conditions (RPV, 2025). An example of the Abalone Cove Reserve Closure is presented on Figure 10-5. Shifting terrain has also damaged and restricted access to hiking and equestrian trails within the Palos Verdes Nature Preserve, particularly in the Portuguese Bend Reserve, where rapid land deformation has rendered portions of the trail network unstable and unsafe for public use. These impacts not only limit public recreation but also affect protected habitat areas, where ongoing land movement disrupts vegetation communities and alters ecological corridors essential for native wildlife.
Source: (RPV, 2025)
Figure 10-5. Example of Beach and Trail Closure (Abalone Cove Reserve Closure)
10.2.8 Change in Vulnerability Since the Prior Planning Area HMPs The risk of landslides and mass movement continues to change as the Palos Verdes Peninsula is an active landslide area. Landslide mitigation activities such as drilling deep dewatering wells have reduced vulnerability in some areas.
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Homes in the Planning Area that have been red or yellow tagged may be unoccupied due to landslide activity, therefore the decrease in residential population in those active landslide areas also reduces the population exposed to the hazard.
The changing climate may lead to increased and more frequent rainfall events, which may exacerbate slope instability and landslide hazards. Although population levels in landslide susceptible areas in the Planning Area have declined, the type and location of new or proposed development remain important factors to monitor. Since the prior mitigation planning efforts, areas within the Planning Area that were previously considered developable are now excluded from future development due to landslide activity.
10.3 MITIGATION OPPORTUNITIES
Table 10-8 presents a range of potential opportunities considered by the Planning Partnership for mitigating the landslide/mass movement hazard.
Table 10-8. Potential Opportunities to Mitigate the Landslide/Mass Movement Hazard Community Scale Organizational Scale Government Scale
Manipulate the Hazard
• Stabilize slope
• Reduce weight on top of slope
• Minimize vegetation removal
and the addition of impervious
surfaces
• Stabilize slope
• Filling in fissures and lining
canyons to minimize water
infiltrating the ground and
water table
• Stabilize slope
• Filling in fissures and lining
canyons to minimize water
infiltrating the ground and
water table
• Reduce weight on top of slope
Reduce Exposure and Vulnerability
• Locate structures outside of
hazard area
• Locate structures outside of
hazard area
• Armor/retrofit critical
infrastructure against the
impact of landslides
• Support transition of high
hazard areas to open space
Build Local Capacity
• Subscribe to warning systems,
and develop evacuation plan
• Keep cash reserves for
reconstruction
• Educate yourself on risk
reduction techniques for
landslide hazards
• Institute warning system, and
develop evacuation plan
• Keep cash reserves for
reconstruction
• Develop a continuity of
operations plan
• Educate employees on the
potential exposure to landslide
hazards and emergency
response protocol
• Provide public with information
on landslide hazard and
appropriate risk reduction
alternatives
Nature-based Opportunities
• Replace or restore native vegetation known to stabilize steep slopes • Hybrid solutions that combine engineering with a nature-based approach using appropriate vegetation
Palos Verdes Peninsula, California | Multi-Jurisdictional Local Hazard Mitigation Plan BLACK & VEATCH | Strong Wind 11-1
11. STRONG WIND
11.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.
11.1.1 Description of the Hazard
Defining the Hazard
Windstorms are generally short-duration events involving straight-line winds or gusts of over 50 miles per hour (mph), strong enough to cause property damage. Windstorms are especially dangerous in areas with significant tree stands and areas with exposed property, poorly constructed buildings, major infrastructure, and above-ground utility lines. A windstorm can topple trees and power lines, cause damage to residential, commercial, and critical facilities, and leave tons of debris in its wake. There are seven primary types of damaging winds (NOAA National Severe Storms Laboratory, n.d.):
• Straight-line winds—Any thunderstorm wind that is not associated with rotation; this term is used mainly to differentiate from tornado winds. Most thunderstorms produce some straight-line winds as a result of outflow generated by the thunderstorm downdraft. • Downdrafts—A small-scale column of air that rapidly sinks toward the ground. • Downbursts—A strong downdraft with horizontal dimensions larger than 2.5 miles resulting in an outward burst or damaging winds on or near the ground. Downburst winds may begin as a microburst and spread out over a wider area, sometimes producing damage similar to a strong tornado. Although usually associated with thunderstorms, downbursts can occur with showers too weak to produce thunder.
• Microbursts—A small, concentrated downburst that produces an outward burst of damaging winds at the surface. Microbursts are generally less than 2.5 miles across and short-lived, lasting only 5 to 10 minutes, with maximum wind speeds up to 168 mph. There are two kinds of microbursts: wet and dry. A wet microburst is accompanied by heavy precipitation at the surface.
Dry microbursts, common in places like the high plains and the intermountain west, occur with little or no precipitation reaching the ground.
• Gust front—A gust front is the leading edge of rain-cooled air that clashes with warmer thunderstorm inflow. Gust fronts are characterized by a wind shift and gusty winds out ahead of a thunderstorm. Sometimes the winds push up air above them, forming a shelf cloud or detached roll cloud.
• Derecho—A derecho is a widespread thunderstorm wind caused when new thunderstorms form along the leading edge of an outflow boundary (the boundary formed by horizontal spreading of thunderstorm-cooled air). The word “derecho” is of Spanish origin and means “straight ahead.” Thunderstorms feed on the boundary and continue to reproduce. Derechos typically occur in summer when complexes of thunderstorms form over plains, producing heavy rain and severe wind. The damaging winds can last a long time and cover a large area (National Weather Service, n.d.).