​​​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 t​he 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 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.

U​PLOAD Geologic/Geotechnical Reports

The Policies and Criteria of the State Mining and Geology Board, with respect to the Alquist-Priolo Earthquake Fault Zoning Act (California Code of Regulations, Section 3603(f)), requires lead agencies to​ file copies of geologic reports of fault studies with the State Geologist within 30 days of its approval. Similarly, the Seismic Hazards Mapping A​ct (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 thes​e reports and associated documentation of approval be submitted in digital format (PDF, MS Word, etc.) through the following link:

​​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 following to request a direct link to the Seismic Hazards Box.com upload folder. Include a return e-mail address ​if different than the sent from address. A Box.com account is required to upload files through this link.

Request access to CGS Box account: Send Mail

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