USA - Liquefaction Hazard and Shaking Amplification Maps of Alameda, Berkeley, Emeryville, Oakland, and Piedmont, California: A Digital Database - USGS

This Open-File Report is a digital database for hazard maps of liquefaction effects and shaking amplification in the Oakland, California, area. This accompanying pamphlet serves to introduce and describe the digital data. Paper maps are not included in the Open-File Report; instead PDF plot files are included that can be used to plot images of the hazard maps.

This digital database is based on a previously published map of surficial geology by Helley and Graymer (1997) as modified by R. Witter (digital communication, 2003) together with 210 newly acquired seismic cone penetration test (SCPT) soundings supplemented by unpublished commercial borings. The database identifies areas that have potential (1) to produce surface manifestations of liquefaction, for example, sand boils, ground cracks, and lateral spreading, and (2) to amplify ground shaking from earthquakes. The scale of the source map limits the spatial resolution (scale) of the database to 1:24,000 and smaller for the liquefaction map and 1:50,000 and smaller for the shaking amplification map; plotting at larger scales will not yield greater real detail. These maps depict the hazard at a regional scale and should not be used for site-specific design. Subsurface conditions can vary abruptly and borings are required to address the hazard at a given location. The liquefaction hazard map also does not account for local ground improvements that have been made to mitigate against the occurrence of liquefaction.

Title:Liquefaction hazard and shaking amplification maps of Alameda, Berkeley, Emeryville, Oakland, and Piedmont, California: a digital database

Author(s): Holzer, T.L., Bennett, M.J., Noce, T.E., Padovani, A.C., and Tinsley, J.C.