Abstract

Earthquakes in California's San Francisco Bay Area are likely to be more strongly affected by stress interaction than earthquakes in any other place in the world because of the region's closely spaced, subparallel distribution of faults. I believe, therefore, that meaningful quantification of earthquake probability and hazard in the Bay Area can be made only with the guidance provided by physically based and regionwide earthquake models that account for this interaction. This article represents a first step in developing a standard physical earthquake model for the San Francisco Bay Area through realistic, 3000-year simulations of earthquakes on all of the area's major faults. These simulations demonstrate that a standard physical earthquake model is entirely feasible, they illustrate its application, and they blueprint its construction. A standard physical earthquake model provides the mechanism to integrate fully the diverse disciplines within the earthquake research community. As a platform for data utilization and verification, a physical earthquake model can employ directly any earthquake property that is measurable in the field or in the laboratory to tune and test its seismicity products. As a platform for probability forecasts, a physical earthquake model can supply rational estimates of every imaginable earthquake statistic while simultaneously satisfying all slip and earthquake rate constraints. As a platform for hazard analysis, a physical earthquake model can compute earthquake shaking intensity from first principles by convolving a full suite of rupture scenarios with site-specific dislocation Green's functions. Physical earthquake models have advanced greatly in the last decade. Simulations of earthquake generation and recurrence are now sufficiently credible that such calculations can begin to take substantial roles in scientific studies of earthquake probability and hazard.

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