A Systematic Analysis of Seismic Moment Tensor at The Geysers Geothermal Field, California

Boyd, O. Sierra and Dreger, Douglas S. and Lai, Voon Hui and Gritto, Roland (2015) A Systematic Analysis of Seismic Moment Tensor at The Geysers Geothermal Field, California. Bulletin of the Seismological Society of America, 105 (6). pp. 2969-2986. DOI: https://doi.org/10.1785/0120140285

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Official URL: http://doi.org/10.1785/0120140285

Abstract

The Geysers geothermal field is one of the most seismically active regionsinnorthernCalifornia.Mostoftheeventsoccuratshallowdepthsandarerelated tostressandhydrologicalperturbationsduetoenergyproductionoperations.Tobetter understand the relationships between seismicity and operations, better source mechanism information is needed. Seismic moment tensors offer insight into the nature of equivalent forces causing the seismicity. Fifty-three M>3 events located at The Geysers geothermal field were selected from the University of California Berkeley Moment Tensor Catalog for analysis of seismic moment tensor solutions and associated uncertainties. Deviatoric and full moment tensor solutions were computed, and statistical tests were employed to assess solution stability, resolution, and significance.Inthisstudy,weexamineseveralsourcemodelsincludingdouble-couple(DC), pure isotropic (ISO; volumetric change), and volume-compensated linear vector dipole (CLVD) sources, as well as compound sources such as DC�CLVD, DC�ISO, and shear–tensile sources. In general, wefind from a systematic approach toward characterizing uncertainties in moment tensor solutions that The Geysers earthquakes, as a population, deviate significantly from northern California seismicity in terms of apparent volumetric source terms and complexity.

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Item Type: Article
Subjects: Methodology > Method and procesing > Source parameter estimation
Region > USA > California > Geysers
Inducing technology > Geothermal energy production
Project: SHEER project > THE GEYSERS: geothermal energy production