Accelerating seismicity and stress accumulation before large earthquakes

The stress field that existed before a large earthquake can be calculated b ased on the known source parameters of the event. This stress field can be used to define a region that shows greater seismic moment rate changes prio r to the event than arbitrarily shaped regions, allowing us to link two pre viously unrelated subjects: Coulomb stress interactions and accelerating se ismicity before large earthquakes. As an example, we have examined all M gr eater than or equal to6.5 earthquakes in California since 1950. While we il lustrate the model using seismicity in California, the technique is general and can be applied to any tectonically active region. We show that where s ufficient knowledge of the regional tectonics exists, this method can be us ed to augment current techniques for seismic hazard estimation.