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U.S. Geological Survey
Open-File Report 03-214

Earthquake Probabilities in the San Francisco Bay Region: 2002–2031

By Working Group On California Earthquake Probabilities


Drawing on new data and new methodologies, we have concluded that there is a 0.62 probability (that is, a 62% probability) of a major, damaging earthquake striking the greater San Francisco Bay Region (SFBR) over the next 30 years (2002–2031). Such earthquakes are most likely to occur on seven main fault systems identified in this study, but may also occur on faults that were not characterized as part of the study (that is, in the “background”) (Figure ES.1). Our results come from a comprehensive analysis lead by the USGS and involving input from a broad group of geologists, seismologists, and other earth scientists representing government, academia and the private sector. The results of this study are appropriate for use in estimating seismic hazard in the SFBR, and estimating the intensity of ground shaking expected for specified “scenario” earthquakes. In addition, they provide a basis for calculating earthquake insurance premiums, planning and prioritizing expenditures for seismic upgrades of structures, and developing building codes.

This report consists of front matter, 8 chapters, references, and appendixes A - G, all available here as Portable Document (PDF) files. The complete report can be downloaded as one file or each section can be downloaded separately.

Download the entire report as a single PDF document (56.6 MB)

Download the title page, table of contents, and executive summary for this report (728 KB; PDF)

Download (chap. 1) Introduction (12 KB; PDF)

Download (chap. 2) Overview of Models and Methodology (2.6 MB; PDF)

Download (chap. 3) Characterization of the SFBR Earthquake Source (11.2 MB; PDF)

Download (chap. 4) The SFBR Earthquake Source Model: Magnitudes and Long-Term Rates (1.1 MB; PDF)

Download (chap. 5) Calculating Earthquake Probabilities for the SFBR (1.5 MB; PDF)

Download (chap. 6) Earthquake Probabilities for the San Francisco Bay Region 2002—2031:
Results and Discussion
(12.2 MB; PDF)

Download (chap. 7) Implications for Earthquake Hazard in the San Francisco Bay Region (6.7 MB; PDF)

Download (chap. 8) Reflections and Future Directions (20 KB; PDF)

Download the references for this report (40 KB; PDF)

Download Appendixes A - G as a single PDF file (6.1 MB)

Download Appendix A: Implications of the Depth of Seismicity for the Rupture Extent of Future
Earthquakes in the San Francisco Bay Area
for this report (4.8 MB; PDF)

Download Appendix B: The Seismogenic Scaling Factor, R for this report (24 KB; PDF)

Download Appendix C: R-factors Inferred from Geodetic Modeling for this report (428 KB; PDF)

Download Appendix D: Magnitude and Area Data for Strike Slip Earthquakes for this report (4.8 MB; PDF)

Download Appendix E: Moment Released by Aftershocks for this report (108 KB; PDF)

Download Appendix F: Estimated Changes in State on San Francisco Bay Region Faults
Resulting from the 1906 and 1989 Earthquakes
for this report (712 KB; PDF)

Download APPENDIX G: Moment-Balancing the Fault Rupture Models for this report (28 KB; PDF)

For questions about the content of this report, contact Mike Blanpied

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Maintained by: Michael Diggles
Created: May 31, 2003
Last modified: May 17, 2005 (mfd)