Pwave velocity variations in the Coso Region, California, derived from local earthquake travel times

摘要: Inversion of 4036 P wave travel time residuals from 429 local earthquakes using a tomographic scheme provides information about three-dimensional upper crustal velocity variations in the Indian Wells Valley-Coso region southeastern California. The are calculated relative to Coso-specific model, corrected for station elevation, weighted, and back-projected along their ray paths through models defined with layers blocks. Slowness surface layer reflect geology, including slow velocities sedimentary basins Rose valleys relatively fast Sierra Nevada Argus Mountains. In depth range 3–5 km inversion images an area reduced compressional western northern Valley but finds no major beneath Coso volcanic field north. These results consistent recent study anomalous shear attenuation region. Between 5 10 depth, low-velocity areas (7% slow) appear at southern end volcanics, reaching east Basin. Numerical tests inversion's resolution sensitivity noise indicate that these anomalies significant well-resolved, while other apparent poorly sampled probably artifacts. seismic data alone not sufficient uniquely characterize physical state regions. Because region's history Pleistocene bimodal volcanism, high heat flow, geothermal activity, geodetic deformation, one possibility is link zones decreased contemporary magmatic activity.