This research is to continue analysis of earthquake data collected in the 1989 Loma Prieta earthquake aftershock series by means of the PASSCAL seismic instruments. This data will be augmented by the USGS Calnet stations and other portable arrays and refraction data. The current project is solving for Vp/Vs in a single-step inversion. The next step is to iteratively solve for Vp and Vp/Vs. A 3-dimensional image of the subsurface properties will be determined which will be used to investigate properties of rocks at depth relative to locked versus creeping portions of the San Andreas fault. The results will also be used to improve locations of earthquakes in the region to investigate geometry of faults and the complex tectonic system. This research is a component of the National Earthquake Hazard Reduction Program.
