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Development Along the San Andreas and San Jacinto Faults:. The Alquist-Priolo Act. Jerry Treiman and Candace Hill, California Geological Survey. Photo by Bill Bryant. 1848. -- from Fremont Survey Library of Congress. Ferdinand Deppe. Base map from railroad survey – 1854-55
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Development Along the San Andreas and San Jacinto Faults: The Alquist-Priolo Act Jerry Treiman and Candace Hill, California Geological Survey Photo by Bill Bryant
1848 -- from Fremont Survey Library of Congress
Ferdinand Deppe Base map from railroad survey – 1854-55 Library of Congress pre-1857 - Missions -
USGS/L.A. Public Library San Joaquin Valley Information Service Fort Tejon San Bernardino Los Angeles Base map from railroad survey – 1854-55 Library of Congress 1855 - ranchos and communities-
Robert Wallace - USGS Fort Tejon San Bernardino Los Angeles Base map from railroad survey – 1854-55 Library of Congress 1857 - Fort Tejon Earthquake -
Palmdale San Bernardino Base map from railroad survey – 1854-55 Library of Congress
Palmdale village founded in 1886
The 1971 Mw 6.6 San Fernando earthquake was associated with surface fault rupture that damaged or destroyed many structures. The Alquist-Priolo (AP) Act was enacted in 1972 following the earthquake. Photos from CGS files
The intent of the AP Act is to prohibit locating structures for human occupancy across the trace of an active fault, thus avoiding the hazard of surface fault rupture. Photo by E. Hart
Initial Faults Zoned Under The Alquist-Priolo Geologic Hazard Zones Act of 1972 175 zone maps issued in 1974
California Geological Survey 10 Region Fault Evaluation and Zoning Program
Alquist-Priolo Earthquake Fault Zoning Act of 1972 Earthquake Fault Zones encompass hazardous faults, which are defined as those faults that are sufficiently active and well-defined. Sufficiently active faults exhibit evidence of Holocene displacement (approx. last 11,000 years). Well-defined - trace detectable by trained geologist.
Earthquake Fault Zones Earthquake Fault Zones are regulatory zones encompassing faults meeting the zoning criteria of sufficiently active and well-defined. Zone boundaries generally are located 500 feet on either side of active faults in order to accommodate imprecise locations of faults and the possible existence of active branches. Portion of Del Sur Quadrangle, Earthquake Fault Zone Map California Geological Survey, 1979
Alquist-Priolo Earthquake Fault Zone Maps (1974 – 2006) Sacramento San Francisco Los Angeles 547 Earthquake Fault Zone Maps issued as of 12/31/2006 36 Counties and 104 Cities affected
92 quadrangles are zoned along the San Andreas and San Jacinto faults in Southern California
Palmdale San Bernardino Earthquake Fault Zones on 29 quadrangles have been revised in recent decades
Palmdale village founded in 1886
Palmdale Highland San Bernardino Yucaipa Desert Hot Springs Moreno Valley Palm Springs San Jacinto Coachella Hemet Alquist-Priolo zoning along the San Andreas and San Jacinto faults in southern California
Palmdale Highland San Bernardino Yucaipa Desert Hot Springs Moreno Valley Palm Springs San Jacinto Coachella Hemet Fault investigations performed in accordance with the Alquist-Priolo Act
Imagery from Fairchild Aerial Surveys - 1928 Palmdale area looking east toward Lake Palmdale
Palmdale area Spence aerial photo - 1936 looking westerly toward Leona Valley Google
Google Fault studies at Ritter Ranch Photo by J. Treiman
San Bernardino area DEM by Google looking northwest across City Creek area Google
Google northwest of City Creek
San Bernardino area DEM by Google looking southeast across City Creek area Google
Google southeast of City Creek
Google southeast of City Creek
San Jacinto Fault San Bernardino region
City of San Bernardino 10 San Bernardino Freeway Colton Loma Linda 215 Riverside Freeway San Jacinto fault in southern San Bernardino
Coachella Coachella Valley
Comparison of original EFZ faults with later mapping by Clark (1984)
Although revisions and updating are still needed, the Alquist-Priolo Earthquake Fault Zones Act has been very effective in protecting new development from the localized hazard of surface fault rupture. Google
1999 Chi Chi (Taiwan) Earthquake and Alquist-Priolo Earthquake Fault Zoning Act “...if development along the Chelungpu fault had occurred under AP regulations, the loss of life and property would have been greatly reduced.” from Rubin and others, 2001, EOS, v. 82, #47 Photo by K. Kelson