叶涛^1,2,,
陈小斌^1,3,,,
黄清华^2,4,,,
崔腾发⁵
1. 应急管理部国家自然灾害防治研究院, 北京 100085
2. 北京大学理论与应用地球物理研究所, 北京 100871
3. 地震动力学国家重点实验室, 中国地震局地质研究所, 北京 100029
4. 河北红山地球物理国家野外科学观测研究站, 北京大学, 北京 100871
5. 中国地震局地震预测研究所, 北京 100036

基金项目: 国家重点研发项目专题（2018YFC1503402-04），国家自然科学基金创新研究群体项目（42021003），中国地震局地壳应力研究所所长基金（ZDJ2019-27）联合资助


详细信息

作者简介: 叶涛, 男, 博士.研究方向大地电磁方法与应用.E-mail:yetao@pku.edu.cn

通讯作者: 陈小斌, 应急管理部国家自然灾害研究院研究员.研究方向地球电磁学.Email:cxb@pku.edu.cn; 黄清华, 北京大学地空学院教授.研究方向地球电磁学.E-mail:huangq@pku.edu.cn

中图分类号: P318

收稿日期:2021-06-06
修回日期:2021-06-17
上线日期:2021-07-10

Three-dimensional electrical resistivity structure in focal area of the 2021 Yangbi M_S6.4 Earthquake and its implication for the seismogenic mechanism

YE Tao^1,2,,
CHEN XiaoBin^1,3,,,
HUANG QingHua^2,4,,,
CUI TengFa⁵
1. National Institute of Natural Hazards, Ministry of Emergency Management of China, Beijing 100085, China
2. Institute of Theoretical and Applied Geophysics, Peking University, Beijing 100871, China
3. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100871, China
4. Hebei Hongshan Geophysical National Observation and Research Station, Peking University, Beijing 100871, China
5. Institute of Earthquake Prediction, China Earthquake Administration, Beijing 100036, China


More Information

Corresponding authors: CHEN XiaoBin,E-mail:cxb@pku.edu.cn ; HUANG QingHua,E-mail:huangq@pku.edu.cn

MSC: P318

--> Received Date: 06 June 2021
Revised Date: 17 June 2021
Available Online: 10 July 2021


摘要
摘要:通过滇西地区大地电磁数据的三维反演研究，获得了云南漾濞6.4级地震震源区三维电阻率结构模型.结果显示漾濞地震震源区存在显著的电性横向不均匀性，漾濞M_S6.4及其地震序列均发生在高-低阻电性过渡区附近的高阻一侧.这一现象在国内外强震区电性结构、速度结构探测中被普遍发现，本文将其归纳为强震孕育与发生的"刚柔性过渡区现象".在漾濞地震区，高阻体向低阻体楔入，遭受发震断裂切割，发生强震.在这一结果的启发下，本文提出"刚柔性楔嵌体地震动力学模型"（简称为"刚柔性楔嵌体模型"）.其要点在于，在区域应力的驱动下，断裂两侧岩体相互作用造成刚度大一侧的岩体楔入到另一侧柔性介质中形成凹凸体结构，集中于发震断层上的最大有效剪应力切割凹凸体结构中的刚性岩体，产生强震.因此，我们认为漾濞地震是在区域构造应力作用下，最大有效剪应力集中于维西—乔后断裂南段西南侧的隐伏断裂，切割楔入到柔性（低阻）区的刚性（高阻）体的结果.
关键词: 漾濞地震/
三维电性结构/
发震机制/
刚柔性楔嵌体模型/
大地电磁

Abstract:We obtained from magnetotelluric data the three-dimensional resistivity model in the focal area of the Yangbi M_S6.4 earthquake. The results show that there is significant electrical lateral inhomogeneity in the focal area. The Yangbi M_S6.4 earthquake and its sequence occurred within the high-resistivity side close to the boundary between the high and lowresistivity zones. This spatial feature of hypocenters has been observed commonly in the results of electrical resistivity and velocity structures for other large earthquakes. We summarize the above feature as the so-called "Rigid-ductile transition zone phenomenon" for seismogenic mechanism. Taking into account the electrical resistivity structure of the Yangbi seismic zone, we propose a "rigid-ductile wedge seismo-dynamic model" (referred to as the "rigid-ductile wedge model") to explain the seismogenic mechanism of the Yangbi earthquake. Driven by the regional stress, the rigid part on one side of a fault can be wedged into the ductile part to form an asperity structure. The rigid mass can be cut by the maximum effective shear stress, leading to a rupture (earthquake). This is the case for the seismogenic mechanism of the Yangbi M_S6.4 earthquake.
Key words:Yangbi earthquake/
Three-dimensional electrical resistivity structure/
Seismogenic mechanism/
Rigid-ductile wedge model/
Magnetotellurics



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