California Has Its Faults….

California has its faults.  Do you know where they are?  We can help!

We recently had an agent’s buyer inquire about a local fault that was near the property he wanted to purchase.  The property was “in” the local fault zone. The buyer asked us if we could provide a “zoomed-in” map of the fault.  We created the map below and sent it to the client at no additional charge:


It is important for homebuyers to investigate the building and permit requirements in the Alquist-Priolo as well as Local Fault study zones.  This can drastically affect building costs and build ability.

Alquist-Priolo Zones are State Mandated Disclosures that have surface rupture capability.  These faults are considered Active Faults as they have shown evidence of surface displacement within the past 11,000 years (also known as the Holocene Period). These zones, which generally extend 660 feet on each side of a known active fault, identify areas where potential fault rupture along an active fault could prove hazardous and identify where special studies are required to characterize hazards to habitable structures.

In addition to the Alquist-Priolo Fault Zones, a number of cities and counties have Local Fault Zones, which they define as Fault Zone Study areas. Local faults include active and potentially active faults which may or may not have shown surface rupture.   Local faults have experienced movement within the last 1.6  million years (also known as the Quaternary Period). The designated areas may warrant special geologic investigations to confirm the presence or absence of active earthquake faults.

For more information about the Alquist-Priolo Act see:

For more information on Local Fault Zones check with your local building department.

Keep in mind, not all counties have these zones, but most in Southern California and the Bay Area do.


Ralph Kephart
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