STRESS AND FAULTING IN THE COSO GEOTHERMAL FIELD: UPDATE AND RECENT RESULTS FROM THE EAST FLANK AND COSO WASH

We integrate new geologic mapping and measurements of stress orientations and magnitudes from wells 34-9RD2 and 58A-10 with existing data sets to refine a geomechanical model for the Coso geothermal field. Vertically averaged stress orientations across the field are fairly uniform and are consistent with focal mechanism inversions of earthquake clusters for stress and incremental strain. Active faults trending NNW-SSE to NNE-SSW are well oriented for normal slip in the current stress field, where the mean Shmin orientation is 108 ° ± 24º in a transitional strike-slip to normal faulting stress regime. These structures bound regions of intense micro-seismicity and are complexly associated wit