Teleseismic evidence for a low-velocity body under the Coso geothermal area

Journal Article · Sat May 10 00:00:00 EDT 1980 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB085iB05p02471· OSTI ID:5285789

Reasenberg, P; Ellisworth, W; Walter, A

Teleseismic P wave arrivals were recorded by a dense array of seismograph stations located in the Coso geothermal area, California. The resulting pattern of relative residuals an area showing approximately 0.2-s excess travel time that migrates with changing source azimuth, suggesting that the area is the 'delay shadow' produced by a deep, low-velocity body. Inversion of the relative residual data for three-dimensional velocity structure determines the lateral variations in velocity to a depth of 22.5 km beneath the array. An intense low-velocity body, which concides with the surface expressions of late Pleistocene rhyolitic volcanism, high heat flow, and hydrothermal activity, is resolved between 5- and 20-km depth. It has maximum velocity contrast of over 8% between 10 and 17.5 km. The shallowest part of this body is centered below the region of highest heat flow; at depth it is elongate in approximately the N-S direction. The hypothesis that this low-velocity body is caused by the presence of partial melt in the middle crust is consistent with the local seismic, geologic, and thermal data.

• Research Organization: U.S. Geological Survey, Menlo Park, California 94025
• OSTI ID: 5285789
• Journal Information: J. Geophys. Res.; (United States), Vol. 85:B5
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
COSO HOT SPRINGS
SEISMIC SURVEYS
ATTENUATION
FLOW RATE
HEAT FLOW
SEISMIC P WAVES
WAVE PROPAGATION
CALIFORNIA
GEOPHYSICAL SURVEYS
NORTH AMERICA
SEISMIC WAVES
SURVEYS
USA
WESTERN REGION
150301* - Geothermal Exploration & Exploration Technology- Geophysical Techniques & Surveys