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
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.
of Required Investigation maps and reports, California Geological Survey
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.