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ALM: An Asperity-based Likelihood Model for California

Stefan Wiemer, & Danijel Schorlemmer

Published 2007, SCEC Contribution #1000

We propose a quasi-stationary earthquake likelihood model for California based on the assumption that small-scale (5-15 km) spatial variations in b-value of the Gutenberg-Richter law are meaningful for forecasting future seismicity. Because the b-value is inversely proportional to differential stress, low b-value patches (b < 0.7) in our model are much more likely to produce large ruptures than high b-value regions (b > 1.0). We calibrated our model based on the micro-seismicity from 1984-2005.5, using all events above the locally determined magnitude of completeness. At each node, Akaike?s Information Criterion is used to decide if a local b-value estimate or a global estimate of b = 0.82 is used in conjunction with the local a-value estimate to produce a forecast.

Key Words
United States, geologic hazards, asperities, statistical analysis, California, models, maximum likelihood, earthquake prediction, San Andreas Fault, seismic risk, risk assessment, tectonics, algorithms, earthquakes, faults, seismotectonics

Wiemer, S., & Schorlemmer, D. (2007). ALM: An Asperity-based Likelihood Model for California. Seismological Research Letters, 78(1), 134-140.