CGS Seismic Hazard Program Maps
Release of Official Maps of New and Revised Earthquake Fault and Seismic Hazard Zones - January 11, 2018
Four new and revised Official Maps of Alquist-Priolo Earthquake Fault Zones and ten Official Maps of Seismic Hazard Zones were released on January 11, 2018 by the California Geological Survey (CGS). Areas covered by Earthquake Fault Zones are within Los Angeles and Napa counties, and affect the cities of Beverly Hills, Culver City, Los Angeles, Napa, Santa Monica, Vallejo, and West Hollywood. These maps are released under the authority of the Alquist-Priolo Earthquake Fault Zoning (AP) Act that was passed following the 1971 San Fernando earthquake. Areas covered by Seismic Hazard Zone maps are within Contra Costa, Riverside and San Mateo counties, and affect the cities of Antioch, Belmont, Brentwood, Burlingame, Foster City, Hillsborough, Menlo Park, Murrieta, Oakley, Redwood City, San Carlos, San Mateo, and Temecula. These maps are released under the authority of the Seismic Hazards Mapping Act that was passed following the 1989 Loma Prieta Earthquake. The AP and Seismic Hazards Mapping acts are state laws designed to protect the public health and safety from the effects of surface fault rupture, strong ground shaking, liquefaction, landslides, or other ground failure and other seismic hazards caused by earthquakes. These Official Zones are regulatory zones that require site-specific geologic/geotechnical investigations to identify and mitigate earthquake hazards.
These new and revised maps show the location of Earthquake Fault Zones and/or Seismic Hazard Zones and are collectively referred to as Earthquake Zones of Required Investigation. An electronic version of the zone maps, referred to as a geo-pdf file, can be viewed using Adobe Acrobat Reader. This geo-pdf file consists of multiple layers and gives the user greater flexibility in viewing and displaying the maps. Geographic information system (GIS) files for both Earthquake Fault and Seismic Hazard zones released by CGS are considered the “Official Maps.” Both GIS and geo-pdf files, as well as associated reports for the January 11 release can be downloaded from the tables below.
Official Maps of New and Revised Alquist-Priolo Earthquake Fault Zones
Official Maps of New and Revised Seismic Hazard Zones