Microearthquake Monitoring at the Southeast Geysers Using a High-resolution Digital Array

Microearthquake activity at the Southeast Geysers, California, geothermal field is monitored with a highresolution digital seismic network. Hypocenters are spatially clustered in both injection and production areas, but also occur in more diffuse patterns, mostly at depths from 1 to 2.8 km. Hypocenters near the injection well DV-11 exhibit a striking correlation with movement of injectate and injectate-derived steam. Preliminary moment tensor results show promise to provide information on the differing source mechanisms resulting from fluid injection and steam extraction.