| 基于三维应变格林函数反演中小震震源机制 |
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| 引用本文： | 周立,林强,范涛.基于三维应变格林函数反演中小震震源机制[J].西北地震学报,2019,41(6):1553-1559. |
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| 作者姓名： | 周立 林强 范涛 |
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| 作者单位： | 中国地震局地震研究所 地震预警湖北省重点实验室, 湖北 武汉 430071;武汉地震科学仪器研究院有限公司, 湖北 武汉 430071;湖北省重大工程地震监测与预警处置工程技术研究中心, 湖北 武汉 430071,中国地震局地震研究所 地震预警湖北省重点实验室, 湖北 武汉 430071;武汉地震科学仪器研究院有限公司, 湖北 武汉 430071;湖北省重大工程地震监测与预警处置工程技术研究中心, 湖北 武汉 430071,中国地震局地震研究所 地震预警湖北省重点实验室, 湖北 武汉 430071;武汉地震科学仪器研究院有限公司, 湖北 武汉 430071;湖北省重大工程地震监测与预警处置工程技术研究中心, 湖北 武汉 430071 |
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| 基金项目： | 国家重点研发计划项目（2017YFC1500804）；中国地震局地震研究所基本科研业务费专项资助项目；中国地震局地壳应力研究所基本科研业务费专项资助项目（项目批准号：IS201726160） |
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| 摘 要： | 随着复杂速度结构反演的发展和高性能计算能力的提升,基于高精度3D介质模型计算格林函数反演震源机制更具可行性。中小地震因具有更好的覆盖和近似点源效应,在区域结构成像中有着广泛的应用。基于波形类的反演方法如波动方程层析成像\,全波形反演都需要震源机制解,而传统的震源机制反演方法不能很好地应用于中小地震。采用有限差分法构建应变格林张量(Strain Green Tensor,SGT)数据库,将合成波形和实际波形按震相截窗并滤波到不同的频带范围,先通过最小化互相关走时差来进行震源重定位,再通过最小化波形残差反演震源机制。通过合成数据测试验证方法的正确性,随后将该方法应用于青藏高原东部边缘龙门山地区,反演一系列M_W3.4～5.7的中小地震震源机制。由于应变格林张量数据库可预先构建,该方法可以应用于(近)实时震源机制解反演。
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| 关 键 词： | 震源机制反演 应变格林函数 青藏高原 有限差分法 波形反演 |
| 收稿时间： | 2019/3/6 0:00:00 |
Inversion of Focal Mechanisms of Small and Moderate Earthquakes Based on a Three-dimensional Strain Green Tensor Database |
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| ZHOU Li,LIN Qiang and FAN Tao.Inversion of Focal Mechanisms of Small and Moderate Earthquakes Based on a Three-dimensional Strain Green Tensor Database[J].Northwestern Seismological Journal,2019,41(6):1553-1559. |
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| Authors: | ZHOU Li LIN Qiang and FAN Tao |
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| Institution: | Hubei Key Laboratory of Earthquake Early Warning, Institute of Seismology, China Earthquake Agency, Wuhan 430071, Hubei, China;Wuhan Institute of Seismologic Instrument Co., Ltd, Wuhan 430071, Hubei, China;Engineering Technology Research Center for Earthquake Monitoring and Early WarningDisposal of Major Projects in Hubei Province, Wuhan 430071, Hubei, China,Hubei Key Laboratory of Earthquake Early Warning, Institute of Seismology, China Earthquake Agency, Wuhan 430071, Hubei, China;Wuhan Institute of Seismologic Instrument Co., Ltd, Wuhan 430071, Hubei, China;Engineering Technology Research Center for Earthquake Monitoring and Early WarningDisposal of Major Projects in Hubei Province, Wuhan 430071, Hubei, China and Hubei Key Laboratory of Earthquake Early Warning, Institute of Seismology, China Earthquake Agency, Wuhan 430071, Hubei, China;Wuhan Institute of Seismologic Instrument Co., Ltd, Wuhan 430071, Hubei, China;Engineering Technology Research Center for Earthquake Monitoring and Early WarningDisposal of Major Projects in Hubei Province, Wuhan 430071, Hubei, China |
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| Abstract: | With the development of complex velocity structure inversion and improvements in high-performance computational power, it has become possible to calculate accurate 3D strain Green tensors (SGT) by means of high-resolution 3D earth models. Due to more uniform distribution and better point source effects, small-to-moderate earthquakes are widely used in local-scale waveform-based tomography. As it is known, waveform-based tomography methods like wave-equation tomography and full waveform inversion (FWI) require focal mechanism solutions during the whole inversion procedure. However, traditional focal mechanism inversion methods are not very suitable to small-to-moderate earthquakes. In this study, we first used the finite differential method to construct a strain Green tensor (SGT) database and filtered the synthetic and actual waveforms in different frequency band ranges. We then relocated the earthquakes by minimizing the cross-correlation travel time differences, and, next, inverted the focal mechanism by minimizing the waveform residuals. Finally, we used this SGT database method to inverse the focal mechanisms of a series of MW3.4-5.7 earthquakes in the Longmenshan fault zone, between the eastern margin of the Tibetan plateau and the western part of Sichuan basin. The results indicated that the proposed method can be applied in (near) real-time inversions of focal mechanism solutions since the database can be pre-constructed. |
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| Keywords: | focal mechanism inversion strain green function Tibet plateau finite differential method waveform inversion |
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