THE ALQUIST PRIOLO EARTHQUAKE FAULT ACT AS A MODEL FOR OTHER HAZARD LOSS REDUCTION ACTIONS

The Alquist-Priolo Earthquake Fault Zoning Act of 1972 has operated successfully in California for the past 35 years. It establishes an active fault zone mapping program and land-use regulations that prevent the placement of human-occupied structures on surface traces of active (<=11 K years) faults .

Jim Slosson's commitment to using hazards information in land use practices was a driving force for implementation of the AP Act. The Act was the template for the Seismic Hazards Mapping Act of 1990, establishing liquefaction and earthquake induced landslide zonation. Vital elements to AP success are accurate establishment of hazard zones, public comment before zones are regulatory, compliance of land-use developers & permiters, license requirements of all participant geologists and performance accountabilities for all parties.

Under the AP Act the State Geologist establishes “zones of required investigation” astride the mapped surface traces of active faults. Zones typically extend out about 500 feet on either side of active fault traces. Before permitting construction in an AP zone cities and counties must require public and private land developers to conduct site-specific geologic investigations of any proposed developments showing that no human-occupied structures will be placed on traces of any active fault. Site-specific geologic investigations are accomplished by private geological consultants hired by the developers. Cities and counties must have geologists independently review developer reports and certify that the investigation was thorough and the conclusions are reasonable and based on acceptable findings. The AP Act requires sellers of human-occupied structures within AP zones to inform prospective buyers that the property is within the zone before any sale.

Accountabilities exist on performance – malpractice by geologists may lead to a loss of license and inability to practice; failure of lead agency enforcement results in liability for property damage and loss of life in AP zones; and, property owners are liable to nullification of transactions when disclosure of the AP zone is not performed.

The opportunity to enact loss-reduction land-use regulations briefly exists after significant events. Pre-event geologic community consensus on future loss-reduction legislation is important.