Seismogenic environment and mechanism of the Yangbi MS6.4 earthquake in Yunnan, China

IF 1.2 4区 地球科学 Q3 Earth and Planetary Sciences
Mengqiao Duan , Kezhen Zuo , Cuiping Zhao , Lianqing Zhou
{"title":"Seismogenic environment and mechanism of the Yangbi MS6.4 earthquake in Yunnan, China","authors":"Mengqiao Duan ,&nbsp;Kezhen Zuo ,&nbsp;Cuiping Zhao ,&nbsp;Lianqing Zhou","doi":"10.1016/j.eqs.2022.08.001","DOIUrl":null,"url":null,"abstract":"<div><p>The Yangbi <em>M</em><sub>S</sub>6.4 earthquake occurred on May 21, 2021 in western Yunnan, China, where moderate earthquakes strike frequently. It exhibited a typical “foreshock-mainshock-aftershock” sequence and did not occur on a pre-existing active fault. The seismogenic environment and mechanism of this earthquake have aroused considerable research attention. In this study, we obtain the three-dimensional <em>v</em><sub>P</sub>, <em>v</em><sub>S</sub> and <em>v</em><sub>P</sub>/<em>v</em><sub>S</sub> images using the <em>v</em><sub>P</sub>/<em>v</em><sub>S</sub> consistency-constrained double-difference tomography method, which improves the accuracy of <em>v</em><sub>P</sub>/<em>v</em><sub>S</sub> models. We focus on characteristics of <em>v</em><sub>P</sub>/<em>v</em><sub>S</sub> images in areas with a lateral resolution of 0.1°, and reveal the seismogenic environment of the Yangbi <em>M</em><sub>S</sub>6.4 earthquake. The conclusions are as follows: (1) Low velocity and high-<em>v</em><sub>P</sub>/<em>v</em><sub>S</sub> anomalies are revealed at different depths around the northern segment of the Red River fault. <em>v</em><sub>S</sub> and <em>v</em><sub>P</sub>/<em>v</em><sub>S</sub> images along the Weixi-Qiaohou-Weishan fault and the buried faults on its west show obviously segmented feature. (2) The source region of the Yangbi <em>M</em><sub>S</sub>6.4 earthquake is located in a low-<em>v</em><sub>P</sub>/<em>v</em><sub>S</sub> zone implying high medium strength. High-<em>v</em><sub>P</sub>/<em>v</em><sub>S</sub> anomalies in its NW direction indicate cracks development and the existence of fluids or partial melts, which are unfavorable for stress accumulation and triggering large earthquakes. Such conditions have also prevented the earthquake sequence from extending northwestward. (3) With the southeastward extrusion of materials from the Tibetan Plateau, fluid migration was blocked by the low-<em>v</em><sub>P</sub>/<em>v</em><sub>S</sub> body in the source region. The high-<em>v</em><sub>P</sub>/<em>v</em><sub>S</sub> anomaly beneath the source region may implies that the fluids or partial melts in the middle and lower crust gradually weakened medium strength at the bottom of the seismogenic layer, and preparing the largest foreshock in the transition zone of high to low <em>v</em><sub>P</sub>/<em>v</em><sub>S</sub>. Meanwhile, tectonic stress incessantly accumulated in the brittle upper crust, eventually led to the <em>M</em><sub>S</sub>6.4 earthquake occurrence.</p></div>","PeriodicalId":46333,"journal":{"name":"Earthquake Science","volume":"35 4","pages":"Pages 297-310"},"PeriodicalIF":1.2000,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674451922003482/pdfft?md5=42b0ca855b3483b8b6d600225a2d318b&pid=1-s2.0-S1674451922003482-main.pdf","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Earthquake Science","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1674451922003482","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"Earth and Planetary Sciences","Score":null,"Total":0}
引用次数: 1

Abstract

The Yangbi MS6.4 earthquake occurred on May 21, 2021 in western Yunnan, China, where moderate earthquakes strike frequently. It exhibited a typical “foreshock-mainshock-aftershock” sequence and did not occur on a pre-existing active fault. The seismogenic environment and mechanism of this earthquake have aroused considerable research attention. In this study, we obtain the three-dimensional vP, vS and vP/vS images using the vP/vS consistency-constrained double-difference tomography method, which improves the accuracy of vP/vS models. We focus on characteristics of vP/vS images in areas with a lateral resolution of 0.1°, and reveal the seismogenic environment of the Yangbi MS6.4 earthquake. The conclusions are as follows: (1) Low velocity and high-vP/vS anomalies are revealed at different depths around the northern segment of the Red River fault. vS and vP/vS images along the Weixi-Qiaohou-Weishan fault and the buried faults on its west show obviously segmented feature. (2) The source region of the Yangbi MS6.4 earthquake is located in a low-vP/vS zone implying high medium strength. High-vP/vS anomalies in its NW direction indicate cracks development and the existence of fluids or partial melts, which are unfavorable for stress accumulation and triggering large earthquakes. Such conditions have also prevented the earthquake sequence from extending northwestward. (3) With the southeastward extrusion of materials from the Tibetan Plateau, fluid migration was blocked by the low-vP/vS body in the source region. The high-vP/vS anomaly beneath the source region may implies that the fluids or partial melts in the middle and lower crust gradually weakened medium strength at the bottom of the seismogenic layer, and preparing the largest foreshock in the transition zone of high to low vP/vS. Meanwhile, tectonic stress incessantly accumulated in the brittle upper crust, eventually led to the MS6.4 earthquake occurrence.

云南杨壁MS6.4级地震发震环境与机制
2021年5月21日,中国云南西部中地震多发地区杨壁6.4级地震发生。它表现出典型的“前震-主震-余震”序列,并没有发生在先前存在的活动断层上。此次地震的发震环境和机制引起了人们的广泛关注。本研究采用vP/vS一致性约束双差层析成像方法获得了vP/vS三维图像,提高了vP/vS模型的精度。研究了横向分辨率为0.1°区域的vP/vS图像特征,揭示了杨壁MS6.4地震的发震环境。结果表明:(1)红河断裂北段周围不同深度均存在低速和高vp /vS异常。沿渭西-桥后-渭山断裂及其西侧隐伏断裂的vS和vP/vS图像显示出明显的分段特征。(2)杨壁MS6.4级地震震源区位于低vp /vS区,高中强度。北西向的高vp /vS异常表明裂缝发育,存在流体或部分熔体,不利于应力积累和引发大地震。这样的条件也阻止了地震序列向西北延伸。(3)青藏高原物质向东南方向挤压,源区低vp /vS体阻挡了流体运移。震源下方的高vP/vS异常可能表明,中、下地壳的流体或部分熔体在发震层底部逐渐削弱了中等强度,并在高、低vP/vS过渡带准备了最大的前震。同时,构造应力在脆弱的上地壳中不断积累,最终导致MS6.4地震的发生。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
Earthquake Science
Earthquake Science GEOCHEMISTRY & GEOPHYSICS-
CiteScore
1.10
自引率
8.30%
发文量
42
审稿时长
3 months
期刊介绍: Earthquake Science (EQS) aims to publish high-quality, original, peer-reviewed articles on earthquake-related research subjects. It is an English international journal sponsored by the Seismological Society of China and the Institute of Geophysics, China Earthquake Administration. The topics include, but not limited to, the following ● Seismic sources of all kinds. ● Earth structure at all scales. ● Seismotectonics. ● New methods and theoretical seismology. ● Strong ground motion. ● Seismic phenomena of all kinds. ● Seismic hazards, earthquake forecasting and prediction. ● Seismic instrumentation. ● Significant recent or past seismic events. ● Documentation of recent seismic events or important observations. ● Descriptions of field deployments, new methods, and available software tools. The types of manuscripts include the following. There is no length requirement, except for the Short Notes. 【Articles】 Original contributions that have not been published elsewhere. 【Short Notes】 Short papers of recent events or topics that warrant rapid peer reviews and publications. Limited to 4 publication pages. 【Rapid Communications】 Significant contributions that warrant rapid peer reviews and publications. 【Review Articles】Review articles are by invitation only. Please contact the editorial office and editors for possible proposals. 【Toolboxes】 Descriptions of novel numerical methods and associated computer codes. 【Data Products】 Documentation of datasets of various kinds that are interested to the community and available for open access (field data, processed data, synthetic data, or models). 【Opinions】Views on important topics and future directions in earthquake science. 【Comments and Replies】Commentaries on a recently published EQS paper is welcome. The authors of the paper commented will be invited to reply. Both the Comment and the Reply are subject to peer review.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信