A Systematic Analysis of Seismic Moment Tensor at The Geysers Geothermal Field, California
A Systematic Analysis of Seismic Moment Tensor at The Geysers Geothermal Field, California
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DOI：
10.1785/0120140285
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发表时间：
2015-12-01
影响因子：
3
通讯作者：
Gritto, Roland
中科院分区：
文献类型：
--
作者：
Boyd, O. Sierra;Dreger, Douglas S.;Gritto, Roland
间歇泉地热田是加州北部地震最活跃的地区之一。大多数事件发生在浅层深处，与能源生产作业引起的应力和水文扰动有关。为了更好地理解地震活动性和作业之间的关系，需要更好的震源机制信息。地震矩张量提供了对引起地震活动的等效力的性质的深入了解。从加州大学伯克利分校的矩张量目录中选择了位于Geysers地热田的53个M b>3事件，用于分析地震矩张量解和相关不确定性。计算偏差和全矩张量解，并采用统计检验来评估解的稳定性、分辨率和显著性。在本研究中，我们研究了几种源模型，包括双偶（DC）、纯各向同性（ISO；体积变化）和体积补偿线性矢量偶极子（CLVD）源，以及复合源，如DC + CLVD、DC + ISO和剪切-拉伸源。总的来说，我们从系统的方法中发现，对矩张量解的不确定性进行表征，间歇泉地震作为一个群体，在表观体积源项和复杂性方面明显偏离北加州地震活动性。
The Geysers geothermal field is one of the most seismically active regions in northern California. Most of the events occur at shallow depths and are related to stress and hydrological perturbations due to energy production operations. To better 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. In this study, we examine several source models including double-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, we find 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.