The purpose of this report is to serve as a catalyst for understanding and mitigating (through avoidance, engineering, planning and response) the liquefaction hazard in the San Francisco Bay Area. As such, the audience is not the geology or engineering community, but rather those who work for and with the local governments, utilities, businesses, and residents in our region.

This report is intended to supplement the maps prepared by William Lettis & Associates, Inc. (WLA), the U.S. Geological Survey (USGS), and the California Division of Mines and Geology (CDMG). It is not a substitute for site-specific advice from a licensed geologist or geotechnical engineer.

This ABAG report is part of a collaborative project with WLA and USGS funded by USGS. As part of this collaborative effort, WLA received funding from USGS to develop new regional consistent maps of Quaternary deposits (materials deposited in the last 1.6 million years) (Knudsen and others, 2000).