Alquist Priolo Special Studies Zone Act
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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. It directs the State of California Division of Mines and Geology to compile detailed maps of the surface traces of known active faults on 1:24,000 scale topographic maps.
Since the Act passed, countless buildings that might have been placed atop surface faults, including hospitals and other vital structures, have been placed on safer ground. The Act was one of several that changed building codes and practices to improve earthquake safety, changes that are now credited with lowering the casualties from earthqaukes in California. For example, the developing of the Belmont Learning Center, a large school complex, in Downtown Los Angeles by the Los Angeles Unified School District (LAUSD) was complicated by discovery of a surface fault on the property in 2002. The LAUSD was required to remove a building that had been built directly atop the fault prior to its discovery.
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Background
This state law was a direct result of the 1971 Sylmar earthquake (also called the San Fernando Earthquake), which was associated with extensive surface fault ruptures that damaged numerous homes, commercial buildings, and other structures. Surface rupture is the most easily avoided seismic hazard.
It went into effect on March 7, 1973. This law was amended a few years later to include a disclosure obligation for real estate licensees.
The Act was called the Alquist-Priolo State Special Studies Zone Act prior to 1994.
Purpose of Act
The Act's main purpose is to prevent the construction of buildings used for human occupancy on the surface trace of active faults. The Act only addresses the hazard of surface fault rupture and is not directed toward other earthquake hazards. The Seismic Hazards Mapping Act, passed in 1990, addresses non-surface fault rupture earthquake hazards, including liquefaction and seismically induced landslides.
The law requires the California State Geologist to establish regulatory zones (known as Earthquake Fault Zones) around the surface traces of active faults and to issue appropriate maps. ("Earthquake Fault Zones" were called "Special Studies Zones" prior to January 1, 1994.) The maps are distributed to all affected cities, counties, and state agencies for their use in planning and controlling new or renewed construction. Local agencies must regulate most development projects within the zones. Projects include all land divisions and most structures for human occupancy. Single family wood-frame and steel-frame dwellings up to two stories not part of a development of four units or more are exempt. However, local agencies can be more restrictive than state law requires.
The Act was Amended September 26, 1974, May 4, 1975, September 28, 1975, September 22, 1976, September 27, 1979, September 21, 1990, and July 29, 1991.
References
California Department of Conservation, DMG, Special Publication 42, Revised 1992
External links
- California Geological Survey page on Alquist-Priolo (http://www.consrv.ca.gov/CGS/rghm/ap/)