Grid-Search for Accelerated Moment Release (AMR) Precursors to California Earthquakes

Accelerated Moment Release (AMR) has been proposed as a potential medium to long-term predictor of large earthquakes. Previous studies have shown that earthquakes in California with magnitudes greater than 6.8 are preceded by an acceleration of intermediate-sized events. We define a false alarm as a period of accelerated regional seismicity that does not culminate in a large earthquake. For AMR to be useful as a predictive tool, acceleration must precede all large earthquakes and the false alarm rate must be small and known. Bowman et al. [1998] and Ikeda [2004] predicted AMR false alarm rates based on a synthetic earthquake catalogs. This study investigates the false alarm rate by using real earthquake catalogs to search for AMR signals across a broad region of California during a period of minimal earthquake activity. The AMR search is conducted on a grid covering the entire State of California. At each grid node a series of AMR calculations is performed to determine if AMR exists within circular regions over any temporal and spatial window. We construct false alarm rate curves base on the number of observed historical AMR sequences that did not culminate in a large earthquake. This provides a baseline for evaluating the utility of accelerating seismicity as a precursory signal before large earthquakes in California.