鲜水河—安宁河断裂带深部构造特征、固体潮应力变化与地震触发相关性研究  

Correlations of the deep structural characteristics,tidal stress variation and earthquake initiation along the Xianshuihe-Anninghe fault zone

作　　者：刘冠男[1] 王志[2,3,4] LIU GuanNan;WANG Zhi(College of Geophysics,Chengdu University of Technology,Chengdu 610059,China;Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China;Southern Marine Science and Engineering Guangdong Laboratory,Guangzhou 510301,China;Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences,Guangzhou 510301,China)

机构地区：[1]成都理工大学地球物理学院,成都610059 [2]中国科学院南海海洋研究所大洋与边缘海地质重点实验室,广州510301 [3]南方海洋科学与工程广东省实验室,广州510301 [4]中国科学院南海生态环境工程创新研究院,广州510301

出　　处：《地球物理学报》2020年第3期928-943,共16页Chinese Journal of Geophysics

基　　金：国家自然科学基金（91955204,41572201）;青藏科考（2019QZKK2704）;地质灾害防治与地质环境保护国家重点实验室开放基金（SKLGP2016K016）资助

摘　　要：本研究通过反演241,561条纵波和209,363条横波高质量的地震走时数据,获得了鲜水河、安宁河断裂带的P波、S波以及泊松比的三维结构模型,并结合相位分析与Schuster测试讨论了该断裂带上地震事件的触发与其深部构造以及固体潮所产生的应力变化三者之间的关系.结果表明,鲜水河—安宁河断裂带26.5°N、28°N、29.5°N以及31.5°N四个位置附近存在低速、高泊松比异常,可能暗示着深部流体(包括部分熔融物质)的上涌.这些大范围分布的流体提高了孕震层的孔隙流体压力,削弱了断层面之间摩擦力,在鲜水河—安宁河断裂带形成了一些具有高度地震活动性的区域.此外,相位分析与Schuster测试的结果表明,鲜水河—安宁河断裂带附近的地震触发与固体潮剪切应力的变化密切相关.综合分析的结果表明,固体潮与构造应力对地震触发可能存在某种“合”的关系.在分布着大量流体的区域,地震事件可能对固体潮更加敏感.The correlation of earthquake initiation,deep structural heterogeneities and stress variation associated with the solid earth tide was discussed based on Three-Dimensional(3D)tomography and Schuster′s test accordingly along the Xianshuihe-Anninghe Fault zone(XAF).The seismic structures were obtained by inverting 241,561 P-wave and S-wave 209,363 travel times from high quality datasets.Results show that anomalies of low velocity and high Poisson′s ratio are present at 26.5°N,28°N,29.5°N and 31.5°N along the XAF,which can be interpreted as fluids(partial melt of deep material)intrusion from the lower crust and/or uppermost mantle.These fluids presumably raises pore fluid pressure of seismogenic layers and reduce the frictions in fault planes,generating several high-seismicity areas along the XAF.Besides,the results of tidal phase analysis and Schuster′s tests indicate that there is a high correlation between earthquake initiation and tidal shear stress variation.A comprehensive analysis illustrates that the solid earth tide and the tectonic stress have a joint effect on earthquake initiation,which is possibly more sensitive to solid earth tide at locations with widespread fluids.

关 键 词：鲜水河—安宁河断裂带 地震层析成像 地震触发 深部构造 固体潮 

分 类 号：P315[天文地球—地震学]