Spatio-temporal seismicity changes and high-resolution fault zone structures associated with recent large earthquakes in China

中国近期大地震的时空地震活动变化及高分辨率断裂带结构

• 批准号: 1447091
• 负责人: Zhigang Peng
• 金额: $ 26.01万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1447091&HistoricalAwards=false
• 关键词: Spatio; temporal; seismicity; changes; resolution

Large earthquakes occur on major fault zones. Obtaining spatio-temporal changes of seismic activities and detailed fault zone properties around the times of large earthquakes are long-sought goals in earthquake seismology. Sometimes large shallow earthquakes are preceded by increased seismic activity also known as ?foreshocks?. However, the exact relationship among foreshocks, mainshock nucleation and fault zone structures are still in debate. Recently several large earthquakes occurred around the Tibetan Plateau in China, and produced significant damages and casualties. These include the 2008 Ms7.3 Yutian, Ms8.0 Wenchuan, the 2010 Ms7.0 Yushu, the 2013 Ms7.0 Lushan, and the 2014 Ms7.3 Yutian earthquakes. Among them, the Yushu and Yutian mainshocks had clear evidence of M4-5 foreshocks, while the Wenchuan and Lushan mainshocks did not., a comprehensive analysis could provide us a better understanding on whether foreshocks exist and their physical mechanisms. This project will support a team to conduct a systematic examination of seismicity changes around the times of these large earthquakes in China, as well as high-resolution imaging of fault zone structures. The study will employ continuous waveforms recorded by permanent seismic stations around the region of each mainshock, as well as dense aftershock deployment. To examine evolutionary changes in seismicity and fault zone processes, the researchers plan to conduct the following tasks: (1) Use a recently developed waveform matched filter technique to detect all earthquakes long before the occurrence of each mainshock; (2) Use newly relocate catalogs to search for spatio-temporal evolutions before mainshock, as well as performing Epidemic Type Aftershock Sequence (ETAS) modeling and deriving source properties; (3) Identify fault zone head waves along the rupture zones of several recent events; and (4) Perform joint inversion of P and FZHWs for high-resolution fault interface properties. With multi-facet techniques and extensive waveform data, they look to obtain a more complete picture on evolutions of seismic activities and their relationship with fault zone processes around the epicenters of several large intra-plate earthquakes in China. This project can provide important new evidence on the existence (or lack of) precursory changes that precede large mainshocks. The obtained results are essential for evaluating the use of foreshocks as forecasting tools and seismic hazard mitigation in these regions. The project will develop data products such as newly detected earthquake catalog and share with other researchers via peer-reviewed publications. This project will support both graduate students and undergraduate interns to conduct scientific research in China, and promote international collaboration. The project is co-supported by the ISE Global Venture Fund.

大地震发生在主要断层区域上。在地震时期，在大地震时期获得地震活动的时空变化和详细的断层区特性是地震地震学的长期目标。有时，大地震发生之前，地震活动增加也称为前壳？但是，前壳，主震成核和断层区结构之间的确切关系仍在争论中。最近，中国藏高原周围发生了几次大地震，造成了重大损害和伤亡。其中包括2008年MS7.3 Yutian，MS8.0 Wenchuan，2010年MS7.0 Yushu，2013 MS7.0 Lushan和2014年MS7.3 MS7.3 Yutian地震。其中，Yushu和Yutian Mainshocks有明确的M4-5前壳证据，而Wenchuan和Lushan Mainshocks却没有。全面的分析可以使我们更好地了解前壳是否存在及其物理机制。该项目将支持一个团队对中国这些大地震的时代以及断层区域结构的高分辨率成像进行系统检查。该研究将采用由每个主震动区域周围永久性地震站记录的连续波形以及密集的余震部署。为了检查地震性和断层带过程的进化变化，研究人员计划执行以下任务：（1）使用最近开发的波形匹配的滤波器技术在每个主震中发生之前很久以来检测所有地震； （2）使用新的重新安置目录在主震前搜索时空的演变，并执行流行病类型的余震序列（ETAS）建模和得出源特性； （3）确定沿最近几个事件的破裂区域的断层区头波； （4）对高分辨率故障界面属性进行P和FZHWS的联合反转。借助多面技术和广泛的波形数据，他们希望获得更完整的地震活动演变及其与中国几个大型板内地震震中周围的断层区域过程的关系。该项目可以提供重要的新证据，表明在大型主弹药之前的存在（或缺乏）前保证变化。获得的结果对于评估预测用作预测工具和减轻这些区域的地震危害至关重要。该项目将开发数据产品，例如新检测到的地震目录，并通过同行评审的出版物与其他研究人员共享。该项目将支持研究生和本科实习生在中国进行科学研究，并促进国际合作。该项目由ISE全球风险基金共同支持。