CGS Seismic Hazard Zonation Program

The 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 a​​lso require sellers of real property (and their agents) within a mapped hazard zone to disclose at the time of sale that the property lies withi​​n such a zone.

​​​​​​Seismic Hazard and Fault Maps,​ Reports & GIS Data

​Find and​ download the following products through our Information Warehouse: Regulatory Maps tool.​

  • Earthquake Zones of ​​​Required ​​Investigation​: Maps showing faults, fault traces, liquefaction zones and earthquake-induced landslide zones​. Available as PDF and GIS Data.​
  • ​Seismic Hazard Zone​ Reports and Fault Evaluation Reports: these reports are provided to accompany and support the Earthquake Zones of ​​​Required ​​Investigation​ maps​. They summarize the methods and sources of information used to prepare the maps. Available as PDF.

​​​​​UPLOAD Geologic/Geotechnical Reports

The Seismic Hazards M​​apping Act (Section 2697(a)) requires cities and counties to submit a copy of each approved geologic/geotechnical report, prepared as a result of the presence of a Seismic Hazard Zone, to the State Geologist within 30 days of its approval.  The California Geological Survey strongly encourages that these reports and associated documentation of approval be submitted in digital format (PDF, MS Word, etc.).

​Single File Upload

​​To upload a single file, or multiple files one at a time, Click here

​Multiple File Upload

If ​​you wish to upload multiple files or entire folders, please click the link below to request access to the Seismic Hazards upload folder. Include your return e-mail address.

Feedback is welcome. Please use the above e-mail link for comments or questions.