Recency of Faulting and Neotectonic Framework in the Dixie Valley Geothermal Field and Other Geothermal Fields of the Basin and Range

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Report: Recency of Faulting and Neotectonic Framework in the Dixie Valley Geothermal Field and Other Geothermal Fields of the Basin and Range

Abstract
We studied the role that earthquake faults play in redistributing stresses within in the earths crust near geothermal fields. The geographic foci of our study were the sites of geothermal plants in Dixie Valley, Beowawe, and Bradys Hot Springs, Nevada. Our initial results show that the past history of earthquakes has redistributed stresses at these 3 sites in a manner to open and maintain fluid pathways critical for geothermal development. The approach developed here during our pilot study provides an inexpensive approach to 1) better define the best locations to site geothermal wells within known geothermal fields and 2) to define the location of yet discovered geothermal fields which are not manifest at the surface by active geothermal springs. More specifically, our investigation shows that induced stress concentrations at the endpoints of normal fault ruptures appear to promote favorable conditions for hydrothermal activity in two ways: 1) Nearby fault ruptures may induce after shocks associated with small amounts of slip on macro fractures along the fault and within the damage zone of the fault, thereby producing open fractures without producing large stress drops on the fault; and 2) when the geothermal field is adjacent to fault rupture endpoints, decreases in fault-normal stress may be large enough to produce significant increases in fracture dilatancy, thereby increasing hydraulic conductivity.We conclude that an understanding of the spatial distribution of active faults and the past history of earthquakes on those faults be incorporated as a standard tool in geothermal exploration and in the siting of future boreholes in existing geothermal fields.

Authors 
Steven G. Wesnousky, S. John Caskey and John W. Bell








Published 
N/A, 2000





DOI 
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Online 
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Citation

Steven G. Wesnousky,S. John Caskey,John W. Bell. 2000. Recency of Faulting and Neotectonic Framework in the Dixie Valley Geothermal Field and Other Geothermal Fields of the Basin and Range. N/A: N/A.