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The Alquist-Priolo Earthquake Fault Zoning (AP) Act was passed into law following the destructive February 9, 1971 Mw 6.6 San Fernando earthquake.  The AP Act provides a mechanism for reducing losses from surface fault rupture on a statewide basis.  The intent of the AP 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. 

Thirteen new and revised Official Alquist-Priolo Earthquake Fault Zone Maps Released September 21, 2012.  Areas covered include parts of Alameda, Imperial, Riverside, San Diego, and Ventura counties.  This release introduces a new graphic presentation of these regulatory zone maps.   Click here to view or download the new and revised Official Maps.


View/Download AP Maps
(AP Maps are now accessible with Seismic
Hazard Zone Maps in the new
Information Warehouse interface

UPLOAD Geologic Reports of Fault Studies

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 following the report’s approval. The California Geological Survey strongly encourages that these reports and associated documentation of approval be submitted in digital format (PDF, MS Word, etc.) through the following link: