Testing Waveform Predictions of 3D Velocity Models Against Two Recent Los Angeles Earthquakes

Nearly half of the national seismic risk is located in Southern California, and about one-fourth is concentrated in Los Angeles County alone (Federal Emergency Management Agency [FEMA], 2000). To assess the seismic hazards that drive this risk, we must forecast the strong ground motions that are likely to be produced by large fault ruptures. The standard probabilistic seismic-hazard model of California calculates shaking intensities according to an ensemble of ground-motion prediction equations (Petersen et al., 2008). These empirical equations have a high aleatory variability, primarily because they do not model much of the ground-motion variance caused by 3D crustal heterogeneities (Strasser and Bommer, 2009).