The Influence of Listric Faults on Formation of Fractures in the Coso Geothermal Field
- Key words
- Coso; Fractures, Coso, listric faults, stress refraction
- Location
- Coso, California
- Conference
- Geothermal Resources Council Transactions
- Year
- 2006
- Session
- Fractures; listric faults; stress refraction
- Language
- English
Abstract
Formation of listric faults in the Coso geothermal field results from the presence of a shallow brittle-ductile transition. Rotation of strain axes as a consequence of high temperature gradients causes normal faults to change dip from relatively high angles (~60°) to low angles (10° to 20°) over a 4 km depth interval as determined from reflection seismic data and analysis of strain axes from focal mechanisms. This rotation of fault planes implies that fractures should also change orientation similarly with depth, thus influencing production and injection strategies.
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