The Alquist-Priolo Earthquake Fault Zoning (AP) Act was passed into law following the February 9, 1971 San Fernando earthquake. This layer maps the active fault zones identified by the Act. The intent of the Act is to ensure public safety by prohibiting the siting of most structures for human occupancy across traces of active faults that constitute a potential hazard to structures from surface faulting or fault creep.

Seismic hazard zone (Alquist-Priolo) for development of the Parcel Inventory dataset for the Housing Element Site Selection (HESS) Pre-Screening Tool.

These features designate the Alquist-Priolo Earthquake Fault Zones as shown on the Official Alquist-Priolo Earthquake Fault Zones Map. The data set is comprised of polygons that form regulatory zone boundaries (Alquist-Priolo Earthquake Fault Zones). These features delineate areas where surface fault rupture previously has occurred, or where local topographic, geological, and geotechnical conditions indicate a potential for permanent ground displacements such that mitigation by avoidance as stated in Public Resources Code Section 2621.5 (https://casetext.com/statute/california-codes/california-public-resources-code/division-2-geology-mines-and-mining/chapter-75-earthquake-fault-zoning/section-26215-generally) would be required.

This data will assist cities and counties in fulfilling their responsibility to prohibit the location of developments and structures for human occupancy across the trace of active faults as required by the Alquist-Priolo Earthquake Fault Zoning Act (Public Resources Code, Division 2, Chapter 7.5, Sections 2621-2630). Local governments can withhold development permits until geologic investigations are conducted for specific sites and mitigation measures are incorporated into development plans. Sellers of property use the maps to check the location of their specific site and, if applicable, disclose to the buyer that the property lies within an earthquake fault zone as required by the Alquist-Priolo Earthquake Fault Zoning Act (PRC Section 2621.9).

For information regarding the scope and recommended methods to be used in conducting the required site investigations, see California Geological Survey (CGS) Special Publication 42, Fault-Rupture Hazard Zones in California (https://www.conservation.ca.gov/cgs/Documents/Publications/Special-Publications/SP_042.pdf).

This data was downloaded from https://maps.conservation.ca.gov/cgs/informationwarehouse/index.html.

This data set contains the Alquist-Priolo Earthquake Fault Zones as shown on the Official Alquist-Priolo Earthquake Fault Zones Maps. The dataset is comprised of polygons that form regulatory zone boundaries (Alquist-Priolo Earthquake Fault Zones). These features delineate areas where surface fault rupture previously has occurred, or where local topographic, geological, and geotechnical conditions indicate a potential for permanent ground displacements such that mitigation by avoidance as stated in Public Resources Code Section 2621.5 would be required.

Analysis of ‘CGS Seismic Hazards Program: Fault Traces’ provided by Analyst-2 (analyst-2.ai), based on source dataset retrieved from https://catalog.data.gov/dataset/8bb3b7b5-f8e3-4c8a-92d6-1a59e1e41adc on 12 February 2022.

--- Dataset description provided by original source is as follows ---

This data set contains the Alquist-Priolo Earthquake Fault Zones and fault traces as shown on the Official Alquist-Priolo Earthquake Fault Zones Map of the {quadName} quadrangle. The dataset is comprised of polygons that form regulatory zone boundaries (Alquist-Priolo Earthquake Fault Zones), lines that show identified fault traces, and label points and leaderlines for fault trace annotation. These features delineate areas where surface fault rupture previously has occurred, or where local topographic, geological, and geotechnical conditions indicate a potential for permanent ground displacements such that mitigation by avoidance as stated in Public Resources Code Section 2621.5 would be required.

--- Original source retains full ownership of the source dataset ---

This dataset is intended for researchers, students, and policy makers for reference and mapping purposes, and may be used for basic applications such as viewing, querying, and map output production, or to provide a basemap to support graphical overlays and analysis with other spatial data.

This data set contains the Alquist-Priolo Earthquake Fault Zones and fault traces as shown on the Official Alquist-Priolo Earthquake Fault Zones Map of the Beverly Hills quadrangle. The dataset is comprised of polygons that form regulatory zone boundaries (Alquist-Priolo Earthquake Fault Zones), lines that show identified fault traces, and label points and leaderlines for fault trace annotation. These features delineate areas where surface fault rupture previously has occurred, or where local topographic, geological, and geotechnical conditions indicate a potential for permanent ground displacements such that mitigation by avoidance as stated in Public Resources Code Section 2621.5 would be required.

Alquist-Priolo Earthquake Fault Zoning Act (1972) and the Seismic Hazards Mapping Act (1990) direct the State Geologist to delineate regulatory "Zones of Required Investigation" to reduce the threat to public health and safety and to minimize the loss of life and property posed by earthquake-triggered ground failures. Cities and counties affected by the zones must regulate certain development "projects" within them. These Acts also require sellers of real property (and their agents) within a mapped hazard zone to disclose at the time of sale that the property lies within such a zone.

NOTE: Fault Evaluation Reports are available for those areas covered by a Regulatory Map however there are reports available for areas outside the Regulatory map boundary. For a complete set of maps available for purchase on CD please contact the CGS Library.

The Alquist-Priolo Earthquake Fault Zones and fault traces as shown on the Official Alquist-Priolo Earthquake Fault Zones Map of the Santa Clara County. Alquist-Priolo fault zones do not correspond with fault rupture zones. The Alquist-Priolo Earthquake Fault Zoning Act was passed in 1972 to mitigate the hazard of surface faulting to structures for human occupancy. This state law was a direct result of the 1971 San Fernando Earthquake, which was associated with extensive surface fault ruptures that damaged numerous homes, commercial buildings, and other structures. Surface rupture is the most easily avoidable seismic hazard. It directs the State of California Department of Conservation - Geological Survey to compile detailed maps of the surface traces of known active faults. The Alquist-Priolo Earthquake Fault Zoning Act's main purpose is to prevent the construction of buildings used for human occupancy on the surface trace of active faults. The 1:24,000-scale (24K) U.S. Geological Survey (USGS) quadrangle boundary data set contains the approximate boundaries of the various 24K USGS quadrangles and the names and indexing codes associated with each 24K quadrangle.

AbstractThis data set contains the Alquist-Priolo Earthquake Fault Zones as shown on the Official Alquist-Priolo Earthquake Fault Zones Maps. The dataset is comprised of polygons that form regulatory zone boundaries (Alquist-Priolo Earthquake Fault Zones). These features delineate areas where surface fault rupture previously has occurred, or where local topographic, geological, and geotechnical conditions indicate a potential for permanent ground displacements such that mitigation by avoidance as stated in Public Resources Code Section 2621.5 would be required.

While Long Beach is less likely than other areas of the State to experience earthquakes, all of California is at higher risk compared to the rest of the country. In an attempt to mitigate potential damages, California passed the Alquist-Priolo Earthquake Zoning Act on December 22, 1972.This pdf map visualizes inferred and known fault lines as well as Alquist-Priolo Special Studies Zones within the City of Long Beach.

This data set contains the Alquist-Priolo Earthquake Fault Zones and fault traces as shown on the Official Alquist-Priolo Earthquake Fault Zones Map of the {quadName} quadrangle. The dataset is comprised of polygons that form regulatory zone boundaries (Alquist-Priolo Earthquake Fault Zones), lines that show identified fault traces, and label points and leaderlines for fault trace annotation. These features delineate areas where surface fault rupture previously has occurred, or where local topographic, geological, and geotechnical conditions indicate a potential for permanent ground displacements such that mitigation by avoidance as stated in Public Resources Code Section 2621.5 would be required.

Alquist-Priolo Earthquake Fault Zoning Act (1972) and the Seismic Hazards Mapping Act (1990) direct the State Geologist to delineate regulatory "Zones of Required Investigation" to reduce the threat to public health and safety and to minimize the loss of life and property posed by earthquake-triggered ground failures. Cities and counties affected by the zones must regulate certain development "projects" within them. These Acts also require sellers of real property (and their agents) within a mapped hazard zone to disclose at the time of sale that the property lies within such a zone. NOTE: Fault Evaluation Reports are available for those areas covered by a Regulatory Map however there are reports available for areas outside the Regulatory map boundary. For a complete set of maps available for purchase on CD please contact the CGS Library.

Abstract: This data set contains the Alquist-Priolo Earthquake Fault Zones and fault traces as shown on the Official Alquist-Priolo Earthquake Fault Zones Map of the USGS quadrangles that are in Monterey County. The dataset is comprised of polygons and lines that form regulatory zone boundaries (Alquist-Priolo Earthquake Fault Zones) and fault traces of areas where surface fault rupture previously has occurred, or where local topographic, geological, and geotechnical conditions indicate a potential for permanent ground displacements such that mitigation by avoidance as stated in Public Resources Code Section 2621.5 would be required.

description: The Alquist-Priolo Earthquake Fault Zoning Act was signed into California law on December 22, 1972 to mitigate the hazard of surface faulting to structures for human occupancy. It directs the State of California Division of Mines and Geology (now known as the California Geological Survey) to compile detailed maps of the surface traces of known active faults. These maps include both the best known location where faults cut the surface and a buffer zone around the known trace(s). (See: Wikipedia http://en.wikipedia.org/wiki/Alquist_Priolo_Special_Studies_Zone_Act).; abstract: The Q3 Flood Data are derived from the Flood Insurance Rate Maps (FIRMs) published by the Federal Emergency Management Agency (FEMA). The file is georeferenced to the earth's surface using the geographic projection and the decimal degree coordinate system. The specifications for the horizontal control of Q3 Flood Data files are consistent with those required for mapping at a scale of 1:24000.FEMA Flood maps for CaliforniaSafety, Natural HazardsFlood Hazards

County Faults/Fault Zones (Per Riverside County General Plan 10/2003). Alquist-Priolo Earthquake Fault Zones have been designated by the California Division of Mines and Geology for the Elsinore, San Jacinto, and San Andreas fault zones in Riverside County. Within the rapidly growing county, State A-P mapping has not kept pace with development. The County of Riverside has zoned fault systems and required similar special studies prior to development. These are referred to as County Fault Zones on Figure S-2 and in the Technical Background Report. Within A-P and County Fault Zones, proposed tracts of four or more dwelling units must investigate the potential for and setback from ground rupture hazards. As there are many active faults in Riverside County, with new fault strands being continually discovered, all proposed structures designed for human occupancy should be required to investigate the potential for and setback from ground rupture. Also of concern are structures, not for human occupancy, that can cause harm if damaged by an earthquake, such as utility, communications, and transportation lifelines. The County regulates most development projects within earthquake fault zones (Figure S-2). Projects include all land divisions and most structures for human occupancy. Before a project can be permitted within an A-P Earthquake Fault Zone, County Fault Zone, or within 150 feet of any other potentially active or active fault mapped in published United States Geological Survey (USGS) or California Division of Mining and Geology (CDMG) reports, a geologic investigation must demonstrate that proposed buildings will not be constructed across active faults.Updated 2/2016 with Thermal and Indio California Geologic Survey Quads

© USGS, California Division of Mining and Geology

This layer is a component of NaturalFeaturesAndHazards.

EARTHQUAKE FAULT ZONE OF REQUIRED INVESTIGATION These zones are delineated to assist cities and counties in fulfilling their responsibilities for protecting the public safety from the effects of earthquake fault rupture as required by the Alquist-Priolo Earthquake Fault Zoning Act (Public Resources Code Sections 2623 et seq). For a general description of the Alquist-Priolo Earthquake Fault Zoning Act and regulations, downloadable official zones and related information, please refer to the California Geological Survey Website at (http://www.conservation.ca.gov/cgs/rghm/ap/Pages/index.aspx) FAULT TRACES Fault trace features are from the California Geological Survey 2010 Fault Map of California and show the location of the ground surface trace of faults that are categorized by age for the past 1.6 million years (previously-defined Quaternary Period). Users of this information should be aware that active faults and earthquakes are the subject of continuing research and that refinement of the interpretations given here are sure to come within a few years. California Geological Survey Bulletin 201, “An Explanatory Text to Accompany the Geologic Map of California,” published separately, contains detailed source index maps and references to all the published and unpublished reports and information used in compiling the 1975 Fault Map of California. For additional information about the 2010 version of this map go to the following (http://www.conservation.ca.gov/cgs/cgs_history/Pages/2010_geologicmap.aspx)

LIMITATIONS 1)This site is not designed for official natural hazards disclosure determination. “Official” natural hazard zones viewed on this site are of insufficient resolution to definitively determine in all cases whether an individual property lies within a earthquake fault zone for disclosure purposes pursuant to California Civil Code Section 1103 et seq.
2)This map may not show all potentially active faults, either within the earthquake fault zones or outside their boundaries. 3)Faults shown within earthquake fault zones are the basis for establishing the zone boundaries. 4)The identification of faults and the location of fault traces are based on based on available data at various scales of accuracy, and have not been field checked. Overlay of zones on other base maps can result in discordance with base map features. 5)DISCLAIMER: The State of California and the Department of Conservation make no representations or warranties regarding the accuracy of these zones or fault traces, or the data from which these zones and fault traces were derived. Neither the State nor the Department shall be liable under any circumstances for any direct, indirect, special, incidental or consequential damages with respect to any claim by any user or any third party on account of or arising from the use of this information.

Earthquake related hazards in California The Alquist-Priolo Earthquake Fault Zoning Act was signed into California law on December 22, 1972 to mitigate the hazard of surface faulting to structures for human occupancy. It directs the State of California Division of Mines and Geology (now known as the California Geological Survey) to compile detailed maps of the surface traces of known active faults. These maps include both the best known location where faults cut the surface and a buffer zone around the known trace(s). Earthquakes happen when two blocks of the Earth's crust move relative to one another. The place where the blocks meet is called a fault, and faults tend to show up as relatively straight lines on maps. Any structure built directly on top of the fault will be torn in two when the blocks move. It's not easy to build a building that can withstand this sort of movement (often several feet in a matter of seconds), so it's best to avoid building directly on top of an active fault. (See: Wikipedia http://en.wikipedia.org/wiki/Alquist_Priolo_Special_Studies_Zone_Act). IMPORTANT!: The liquefaction and earthquake induced land slide data used for this map service are NOT statewide and are limited to select locations in the San Francisco Bay Area and Southern California.

EARTHQUAKE FAULT ZONE OF REQUIRED INVESTIGATION These zones are delineated to assist cities and counties in fulfilling their responsibilities for protecting the public safety from the effects of earthquake fault rupture as required by the Alquist-Priolo Earthquake Fault Zoning Act (Public Resources Code Sections 2623 et seq). For a general description of the Alquist-Priolo Earthquake Fault Zoning Act and regulations, downloadable official zones and related information, please refer to the California Geological Survey Website at (http://www.conservation.ca.gov/cgs/rghm/ap/Pages/index.aspx) FAULT TRACES Fault trace features are from the California Geological Survey 2010 Fault Map of California and show the location of the ground surface trace of faults that are categorized by age for the past 1.6 million years (previously-defined Quaternary Period). Users of this information should be aware that active faults and earthquakes are the subject of continuing research and that refinement of the interpretations given here are sure to come within a few years. California Geological Survey Bulletin 201, “An Explanatory Text to Accompany the Geologic Map of California,” published separately, contains detailed source index maps and references to all the published and unpublished reports and information used in compiling the 1975 Fault Map of California. For additional information about the 2010 version of this map go to the following (http://www.conservation.ca.gov/cgs/cgs_history/Pages/2010_geologicmap.aspx)

LIMITATIONS 1)This site is not designed for official natural hazards disclosure determination. “Official” natural hazard zones viewed on this site are of insufficient resolution to definitively determine in all cases whether an individual property lies within a earthquake fault zone for disclosure purposes pursuant to California Civil Code Section 1103 et seq.
2)This map may not show all potentially active faults, either within the earthquake fault zones or outside their boundaries. 3)Faults shown within earthquake fault zones are the basis for establishing the zone boundaries. 4)The identification of faults and the location of fault traces are based on based on available data at various scales of accuracy, and have not been field checked. Overlay of zones on other base maps can result in discordance with base map features. 5)DISCLAIMER: The State of California and the Department of Conservation make no representations or warranties regarding the accuracy of these zones or fault traces, or the data from which these zones and fault traces were derived. Neither the State nor the Department shall be liable under any circumstances for any direct, indirect, special, incidental or consequential damages with respect to any claim by any user or any third party on account of or arising from the use of this information.

Analysis of ‘CGS Information Warehouse: Regulatory Maps’ provided by Analyst-2 (analyst-2.ai), based on source dataset retrieved from https://catalog.data.gov/dataset/6c006a45-901c-4ff0-8c60-34111b3f28a7 on 12 February 2022.

--- Dataset description provided by original source is as follows ---

Alquist-Priolo Earthquake Fault Zoning Act (1972) and the Seismic Hazards Mapping Act (1990) direct the State Geologist to delineate regulatory "Zones of Required Investigation" to reduce the threat to public health and safety and to minimize the loss of life and property posed by earthquake-triggered ground failures. Cities and counties affected by the zones must regulate certain development "projects" within them. These Acts also require sellers of real property (and their agents) within a mapped hazard zone to disclose at the time of sale that the property lies within such a zone.

NOTE: Fault Evaluation Reports are available for those areas covered by a Regulatory Map however there are reports available for areas outside the Regulatory map boundary. For a complete set of maps available for purchase on CD please contact the CGS Library.

--- Original source retains full ownership of the source dataset ---