NEHRP Clearinghouse
- Title
- Microearthquake Investigation of the Mesa Geothermal Anomaly, Imperial Valley, California.
- File
- PB262571.pdf
- Author(s)
- Combs, J.
- Source
- Bureau of Reclamation, Washington, D.C.; National Science Foundation, Washington, D.C. Research Applied to National Needs., June 1974, 40 p.
- Identifying Number(s)
- IGPP-UCR-74-25
- Abstract
- Microearthquakes associated with the Mesa Geothermal Anomaly were recorded for five weeks using an array of six portable, high-gain seismographs equipped with vertical-component 1-sec natural period seismometers. Background seismicity of the area was thus determined prior to development for geothermal power and water. The seismicity changed considerably over the period of recording. Locations were determined for 36 microearthquakes having epicenters situated in the 150 sq km areal extent of the anomaly. A new right-lateral strike-slip fault, the Mesa Fault, was defined and based on the results of the present study. The northwest-southwest trending Mesa Fault is an active fault functioning as a conduit for rising geothermal fluids of the Mesa Geothermal Anomaly. This investigation is another demonstration that geothermal areas are characterized by high microearthquake activity. Stress, associated with these geothermal anomalies, is relieved by a combination of continuous seismic activity and intermittent microearthquake swarms.
- Keywords
- ; Imperial Valley; Tectonics; Geothermal prospecting; California; Fluid infiltration; Pressure; Seismic prospecting; Earthquakes; Geophysical prospecting; Faults (Geology)