THE SFBR EARTHQUAKE SOURCE MODEL: MAGNITUDES AND LONG-TERM RATES Introduction: Calculating Rupture Source Rates in a Complex Model

The tectonically complex San Francisco Bay Region (SFBR) contains both known and unidentified faults that produce a broad range of earthquake sizes at different rates of occurrence. In this chapter we use fault zone information developed in the previous chapter to construct an earthquake source model that describes long-term rates of earthquake production in the SFBR. Specifically, this SFBR earthquake model defines the sizes and locations of earthquake rupture sources in the region, the magnitudes of the earthquakes produced by those sources, and the long-term recurrence rates of those earthquakes. The earthquakes described by the model include large segment-breaking and floating events on the seven characterized faults, and background events on uncharacterized or unknown faults. The SFBR earthquake model is constructed using the variety of geologic, geodetic, and seismic data summarized in the previous chapter, and is faithful to what is currently known about the rates of seismic moment accumulation and release across the region.