2021年云南漾濞MS6.4地震震前地壳形变特征研究

doi:10.12196/j.issn.1000-3274.2022.03.002

摘要/Abstract

摘要： 2021年5月云南大理州漾濞发生一系列中强地震, 其主震达到M_S6.4, 主震震中位于滇南块体内部的维西—乔后—巍山断裂西南侧, 发震断层可能为维西—乔后—巍山断裂的次级分支断裂, 地表走向约为135°。本文收集1998年以来的震中周边GPS测站观测数据, 研究了此次地震序列震前区域地壳的水平形变特征及其与此次地震的关系。结合构造分析认为, 漾濞地震发生在GPS测站水平运动速度陡变区域, 该区域地壳水平运动受阻; 震中区域应变积累明显, 处于面应变率高值区, 且为最大剪应变率的高低值转换区, 符合易发地震区域特性。震中及其邻区的孕震环境以右旋剪切为主, 兼具东西向拉张作用。

关键词: 2021年漾濞M_S6.4地震, 滇南地区, GPS基线, 地壳形变

Abstract: In May 2021, a series of moderate earthquakes occurred in Yangbi, Yunnan Province, which seriously threatened the safety of people’s lives and property. The epicenter of Yangbi M_S6.4 earthquake is located near the Weixi—Qiaohou—Weishan fault in the South Yunnan block. The seismogenic fault is a newly discovered fault with a strike of 135°. Based on GPS observation data from 1998 to 2020, the long-term crustal movement velocity field in the study area is obtained, and the horizontal deformation background characteristics of the regional crust before these strong earthquakes in Yangbi are studied, as well as its relationship with the occurrence of earthquakes. Combined with the structural analysis, it is considered that the Yangbi earthquake occurred in the area where GPS horizontal velocity steeply change. Here the horizontal crustal movement was blocked and the strain accumulation is obvious with the high value area of surface strain rate and maximum shear strain rate. The seismogenic faults in this area are mainly affected by dextral shear and E-W extension.

Key words: the 2021 Yangbi M_S6.4 earthquake, South Yunnan, GPS baseline, Crustal deformation

中图分类号:

P315.7

邹芳, 孟国杰, 苏小宁, 吴伟伟, 赵倩, 佘雅文, ThantMyo. 2021年云南漾濞M_S6.4地震震前地壳形变特征研究[J]. 地震, 2022, 42(3): 21-36.

ZOU Fang, MENG Guo-jie, SU Xiao-ning, WU Wei-wei, ZHAO Qian, SHE Ya-wen, Thant Myo. Characterstics of Tectonic Deformation before the 2021 Yangbi M_S6.4 Earthquake in Yunnan[J]. EARTHQUAKE, 2022, 42(3): 21-36.

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