广西北流 — 广东化州 MS5.2 级地震发震构造探讨-华南地震

文章信息/Info

Title:: Discussion on the Seismogenic Structure of the Beiliu-Huazhou MS 5.2 Earthquake in the Junction of Guangxi and Guangdong

作者:: 王小娜 1; 2; 邓志辉 1; 2; 王力伟 1; 杨选 1; （ 1. 广东省地震局 , 广州 510070； 2. 南方海洋科学与工程广东省实验室 , 广东珠海 519000）

Author(s):: WANG Xiaona1; 2; DENG Zhihui1; 2; WANG Liwei1; YANG Xuan1; （ 1.Guangdong Earthquake Agency, Guangzhou 510070,China;2.Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519000,China）

Keywords:: Beiliu-Huazhou MS5.2 earthquake; Foreshock; Double-Difference seismic location method; Focal mechanism; Michang-Shiwo fault

摘要:: 2019 年 10 月 12 日广西北流与广东化州交界发生 5.2 级地震 , 地震发生前 2 s, 其北西侧发生 4.2 级前震。根据地震周边 47 个台站记录到的 P 波及 S 波震相走时数据 , 利用双差地震定位方法获取了 104 个地震的精定位结果 , 结合 4.2 级前震的震源机制解及 5.2 级主震的 “ 中心震源机制解 ” 进行研究探讨 , 综合分析认为 NW-SE 向米场 — 石窝断裂可能是北流 4.2 级前震和 5.2 级主震的主要发震构造 , 前震孕震过程有 NEESWW 向茶山断裂的参与。而 5.2 级主震位于米场 — 石窝断裂与 NE-SW 向信宜 — 廉江断裂交汇处 , 该交汇处应力薄弱且距离前震仅 1km 左右 , 推测 4.2 级前震的发生可能对 5.2 级地震具有触发作用 ,5.2 级地震发生后余震主要沿米场 — 石窝断裂的延伸线分布。

Abstract:: The MS5.2 earthquake occurred at the junction of Huazhou city of Guangdong province and Beiliu city of Guangxi province. There is a ML4.2 earthquake occurred 2 sec before the MS5.2 earthquake. This paper obtains 135 relocated earthquakes by applying Double-Difference seismiTc location method and the focal mechanism of the foreshock and mainshock. The research suggests that Michang-Shiwo fault with NW-SE trending might be the main seismogenic structure of the foreshock and mainshock. Additional,the Chashan fault with NEE-SWW trending involves the pregnant process of the ML4.2 foreshock. The MS5.2 mainshocklocates at the intersection of Michang-Shiwo fault and Xinyi-Lianjiang fault,while the intersection is only about 1km from the foreshock, which suggests that the ML4.2 foreshock might trigger the MS5.2 mainshock.Finally,the aftershock sequence distributes along the extension line of the Michang-Shiwo fault.