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​​​​​​​The Alquist-Priolo Earthquake Fault Zoning (AP) Act

​​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. 

Three revised Preliminary Alquist-Priolo Earthquake Fault Zone maps have been released as of December 15, 2016.  Areas covered are within Los Angeles County and affect the cities of Arcadia, Los Angeles, Monrovia, Pasadena, San Marino, and South Pasadena.​  Following a review period that ends March 15, 2017, these maps will be superseded by Official Revised Maps on or about June 15, 2017, at which time the zoning becomes effective.  The Preliminary Earthquake Fault Zone maps and their associated Fault Evaluation Reports can be viewed or downloaded here​.



UPLOAD Geologic/Geotechnical 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 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.) through the following link:

Single File Upload

To upload a single file, or mutiple 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 upload folder. Include a return e-mail address if different than the sent from address. A 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.