Public Notification – Release of Preliminary Review Maps of Proposed Revised Earthquake Fault Zones

Preliminary Review Maps of proposed new and revised Alquist-Priolo Earthquake Fault Zones were released to the City of La Cañada Flintridge by the Department of Conservation, California Geological Survey (CGS) on June 6, 2025.  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.  The AP Act is a state law designed to reduce the hazard from surface fault rupture during an earthquake.

Earthquake Fault Zones are regulatory zones that encompass surface traces of active faults that have a potential for future surface fault rupture.  These zones generally are delineated by establishing a buffer area about 500 feet on either side of the surface trace of active faults.  The accompanying map shows the general location of the proposed Earthquake Fault Zones within La Cañada Flintridge. Detailed maps can be obtained from the CGS website https://www.conservation.ca.gov/cgs/preliminary-releases.

What does it mean to be located within an Earthquake Fault Zone?  It means that an active fault is present within the zone and the fault may pose a risk of surface fault rupture to existing or future structures.  If property is not developed, a fault study may be required before the parcel can be subdivided or before most structures can be permitted.  If a property is developed, the AP Act requires that the fact that the property is located within an Earthquake Fault Zone be disclosed by the seller to a prospective buyer for all real estate transactions.  Additional information on Earthquake Fault Zones and disclosure can be found at the CGS Alquist-Priolo web page https://www.conservation.ca.gov/cgs/alquist-priolo.

The June 6, 2025 release date begins a 90-day public comment period designed to provide the opportunity for the State Mining and Geology Board to receive technical review comments that may have a bearing on the proposed Earthquake Fault Zones maps.  Comments should be sent to the State Mining and Geology Board before September 4, 2025.  Comments should be addressed to:

Jeffrey Schmidt, Executive Officer

State Mining and Geology Board

710 P Street, MS 1909

Sacramento, CA  95814

Email: smgb@conservation.ca.gov

(916) 322-1082

The State Mining and Geology Board (SMGB) will hold a public hearing near the end of the 90-day review period.  For more information on the date and location of the public hearing, contact the SMGB (https://www.conservation.ca.gov/smgb).