LandAmerica

The California State Geologist has the responsibility for mapping earthquake fault zones. Fault zones lie on either side of known faults and are generally a quarter mile or less in width. Faults can be categorized as active or inactive and are subject to continual revision as new findings dictate.

The Alquist Priolo Earthquake Fault Zoning Act was passed in 1972 to mitigate the hazard of surface faulting to structures for human occupancy. This California law was a direct result of the 1971 San Fernando Earthquake, which was associated with extensive surface fault ruptures that damaged many residential and commercial structures. Surface fault rupture happens when movement on a fault deep within the earth breaks through the surface. Rupture may occur suddenly during an earthquake or slowly in the form of fault creep.

Just as with FEMA flood zones, lying outside of the fault zone boundary does not ensure that there is no danger from earthquake-generated ground shaking, but it is presumed that there is a greater statistical danger within the zone. More information may be obtained from the California Department of Conservation, Division of Mines and Geology through their nearest office or through the world wide web address, http://www.consrv.ca.gov .