This research is to investigate and model anomalous particle motions and coda of seismic body waves received at broad-band TERRAscope stations in the active seismic region of southern California. These effects are believed to be due to lateral heterogeneity, including faults, near the stations. Understanding the effects of lateral velocity heterogeneity is essential for evaluating errors in waveform modeling using simple 1-D earth models and determining wave scattering mechanisms within the lithosphere. The anomalous observations themselves may be useful in inferring constraints on the type and magnitude of heterogeneity. Data from all available TERRAscope stations will be investigated for inference of lateral heterogeneity. In addition to velocity heterogeneity due to geologic structure, effects of topography will be investigated to determine if topography plays a major role in formation of P wave coda and the interpretation of the P waveform particle motions. This research is a component of the National Earthquake Hazard Reduction Program.
