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).