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Non-shear focal mechanisms of earthquakes at The Geysers, California and Hengill, Iceland, geothermal areas

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, , and
Edited by:
Anon

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Abstract

Several thousand earthquakes were recorded in each area. We report an initial investigation of the focal mechanisms based on P-wave polarities. Distortion by complicated three-dimensional crustal structure was minimized using tomographically derived three-dimensional crustal models. Events with explosive and implosive source mechanisms, suggesting cavity opening and collapse, have been tentatively identified at The Geysers. The new data show that some of these events do not fit the model of tensile cracking accompanied by isotropic pore pressure decreases that was suggested in earlier studies, but that they may instead involve combination of explosive and shear processes. However, the confirmation of earthquakes dominated by explosive components supports the model that the event are caused by crack opening induced by thermal contraction of the heat source.

Additional Publication Details

Publication type:
Conference Paper
Publication Subtype:
Conference Paper
Title:
Non-shear focal mechanisms of earthquakes at The Geysers, California and Hengill, Iceland, geothermal areas
ISBN:
0934412715
Volume
17
Year Published:
1993
Language:
English
Publisher:
Publ by Geothermal Resources Council
Publisher location:
Davis, CA, United States
Larger Work Title:
Transactions - Geothermal Resources Council
First page:
123
Last page:
128
Conference Title:
Proceedings of the 1993 Annual Meeting on Utilities and Geothermal: An Emerging Partnership
Conference Location:
Burlingame, CA, USA
Conference Date:
10 October 1993 through 13 October 1993