This document was written by Peter L. Ward, USGS, with additional comments and advice from Richard Eisner, BAREPP; Jeanne Perkins, ABAG; James Davis, CDMG; Susan Tubbesing, EERI; Robert Bruce, ATC; Dennis Mileti, Colorado State University; Joanne Nigg, University of Delaware; Richard Andrews, California Office of Emergency Services; Thomas Tobin, California Seismic Safety Commission; Peter Yanev, EQE Engineering; Chris D. Polland, H.J. Degenkolb Associates, Engineers; William Bakun, William Ellsworth, Thomas Holzer, Allan Lindh, William Prescott, Paul Reasenberg, Robert Wallace, and Randall White, USGS, and dozens of other people concerned with earthquake hazard reduction.

Edited by Jeffrey Troll, USGS, with assistance from Michael Blanpied and Helen Gibbons, USGS, and Sarah Nathe, BAREPP.

Art Direction: Steven J. Epstein, Publication Arts Network.
Design: Michael Zipkin.
Computer Illustrations: Roger Gilbertson and Chuck Overton.
Translation to Spanish by Carlos Valdes-Gonzalez. Translation to Chinese by Margaret Wu. Edited in Chinese by Yi-Ben Tsai, Pacific Gas and Electric Company, and Chi-Yu King, USGS.Translations funded by The San Francisco Foundation.
Additional funds provided by the USGS, FEMA, and Pacific Telephone.
Satellite image of the Bay Area processed courtesy of the Environmental Research Institute of Michigan, Ann Arbor, Michigan.
Photographs by staff of the USGS and EQE Engineering.

This publication is meant to be instructional and to provide information that will help you understand and reduce the risk from earthquakes. The information in this publication is believed to be accurate at the time of publication. The agencies and individuals involved in the preparation, printing, and distribution of this publication assume no responsibility for any damage that arises from any action that is based on information found in this publication.