December 22, 1972
Impact to Structural Engineering History in Northern California

With its large number of known active faults, the San Francisco Bay Area was a strong candidate for the implementation of this legislation. While subsequent legislation has addressed additional earthquake hazards such as liquefaction and landslides, the Alquist-Priolo Earthquake Fault Zoning Act was the first of its kind to locate active faults and require human occupied structures be located away from them.


The Alquist-Priolo Earthquake Fault Zoning Act was signed into California law on December 22, 1972, to mitigate the hazard of surface faulting to structures for human occupancy. The act was a direct result of the large volume of damage to homes and businesses that occurred in the 1971 San Fernando earthquake due to surface fault rupture.

To increase earthquake safety, the Alquist-Priolo Earthquake Fault Zoning Act enforces the following:

  • Directs the California Geological Survey (CGS) to create maps of known fault zones.
  • Requires the sale of any home located within the fault zone designated on the maps to disclose that the property lies adjacent to a know fault.
  • Prohibits new construction of homes within these zones unless geologic studies are performed to prove that the fault will not pose a hazard to new structures proposed in these zones.
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