Alquist-Priolo Earthquake Fault Zone

Ground shaking causes most earthquake damage, but surface fault rupture was California's first statutory natural hazard disclosure. Slippage on a fault deep within the earth can break through the ground surface, shifting the landscape and everything else crossing the fault trace - fields, fences, streets, sidewalks, homes, hospitals, and water, sewer and gas pipelines. Active earthquake fault zones are a material fact in real estate.

In this episode:

  • The Alquist-Priolo fault zoning law
  • Surface rupture on an "active" fault
  • Zone of required investigation

Why is this important?

  • These faults, considered "active" by the State Geologist, are zoned and regulated to avoid surface fault-rupture hazard.
  • Disclosure to a buyer is required under state law if a property is in this zone.
  • The county or city General Plan Safety Element may provide maps of "potentially active" and "inactive" fault zones which local planners may also regulate.
  • This disclosure is included in First American NHD and JCP-LGS disclosure reports.

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