San Francisco Bay Region Geology and Geologic Hazards

A cooperative project with the California Geological Survey

Liquefaction Downloads Related to the San Francisco Bay Area

Maps and information about liquefaction in the San Francisco Bay region are available for download from several places on the Web. These range from the results of basic research to State regulations, include digital map data and site-specific geotechnical borings, and cover all or part of the region.

  • Maps from which the liquefaction susceptibility map was compiled.
    These sites offer small-scale maps (large area and less detail) of both liquefaction susceptibility and the underlying Quaternary deposits, as well as the higher-resolution digital spatial data from which they were prepared. Liquefaction susceptibility is delineated in five units from Very High to Very Low hazard.

    • USGS Open File Report 00-444
      Covers the whole 9-county San Francisco Bay region, with maps at 1:275,000 and spatial data at one of two finer resolutions in different parts of the region: 1:24,000 and 1:100,000.

    • USGS Open File Report 2006-1037
      Covers the central part of the San Francisco Bay region, brings most of the lower resolution parts of USGS OFR 00-444 up to 1:24,000 standards, and provides a better method for estimating liquefaction susceptibility from mapped Quaternary deposits.

  • Zone of Required Investigation maps and reports, California Geological Survey External link - link policy applies
    These maps define regulatory zones within which site specific studies will be required for new construction. Sellers must disclose when property lies within one of these zones. The maps differ from the hazard maps above in delineating a single zone of required investigation, not several map units of different level of hazard. From this site one can also obtain digital spatial data and geotechnical boring data.

  • USGS CPT data
    From this link, one may download Cone Penetration Test (CPT) data from more than 200 soundings in Alameda County (and elsewhere). These data, collected by the U.S. Geological Survey, were used to develop liquefaction hazard maps of the Oakland, Berkeley and Alameda areas.

  • Historical occurrences of liquefaction
    USGS Open-File Report 00-444 includes a digital compilation of historical occurrences of liquefaction in the San Francisco Bay region prepared from a report on historical effects by Youd and Hoose (1978) and a report on liquefaction caused by the 1989 Loma Prieta earthquake by Tinsley and others (1998). The 1:275,000-scale liquefaction susceptibility map in OFR 00-444 includes these locations of past liquefaction.


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Page Last Modified: 8/18/2006