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《地震研究》[ISSN:1000-0666/CN:53-1062/P]

卷:

46

期数:

2023年02期

页码:

245-260

栏目:

出版日期:

2023-06-01

文章信息/Info

Title:

Characteristics of 3D Velocity Structure in the Arcuate Tectonic Belt of Southeastern Yunnan

作者:

曹 颖¹; 付 虹¹; 钱佳威²

(1.云南省地震局,云南 昆明 650224; 2.中国科学技术大学 地球和空间科学学院,安徽 合肥 230026)

Author(s):

CAO Ying¹; FU Hong¹; QIAN Jiawei²

(1.Yunnan Earthquake Agency,Kunming 650224,Yunnan,China)(2.School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,Anhui,China)

关键词:

滇东南;  弧形构造区;  地壳三维速度结构;  V_P/V_S

Keywords:

southeastern Yunnan;  arcuate tectonic belt;  3D crustal velocity structure;  V_P/V_S

分类号:

P315.2

DOI:

10.20015/j.cnki.ISSN1000-0666.2023.0024

摘要:

利用2008—2021年云南地震台网记录到的M≤5.1地震走时数据,采用V_P/V_S模型一致性约束的双差层析成像方法,获得了滇东南弧形构造区的地壳三维V_P、V_S和V_P/V_S模型及地震重定位结果。结果表明,研究区内发生的2018年8月13日通海M_S5.0地震和2021年6月10日双柏M_S5.1地震的震源深度主要位于V_P,V_S的高、低速异常的交界处或低速异常体的边缘,及低V_P/V_S异常体内。这可能意味着这2个地震所处深度范围内的流体或熔融对地震的发生没有直接作用,而是因为震源位置介于脆、韧性岩体之间,当能量积累到一定程度后该位置更易发生脆性破裂。小江断裂、曲江断裂和石屏—建水断裂下方深处存在高V_P/V_S异常体,结合区内温泉地球化学研究,推测高V_P/V_S异常体可能是地热流体而非熔融物质,地热流体的存在可能会削弱已表现为强闭锁的小江断裂带与曲江断裂和石屏—建水断裂相交处的闭锁体,从而降低断层破坏的构造应力阈值并加速地震孕育过程,应重点关注地热流体的影响。

Abstract:

This paper used the seismic travel-time data from January 2008 to December 2021 recorded by the Yunnan Seismic Network,and adopted a new TomoDDMC method that can improve the resolution and reliability of the V_P/V_S model to obtain the three-dimensional crustal V_P,V_S and V_P/V_S models,as well as the seismic relocation results in southeastern Yunnan.The results show that the 2018 Tonghai M_S5.0 earthquake and the 2021 Shuangbai M_S5.1 earthquake occurring in the study area are mainly located at the junction of the areas with high- and low-velocity anomalies,or at the edge of the area with low-velocity but low V_P/V_S anomaly.It is possible that the fluid or melting material within the depth range of these two earthquakes has no direct effect on the occurrence of them,but because they are between brittle and ductile rock mass,brittle fracture easily occurs when the energy is accumulated to a certain level.We also find that there are high V_P/V_S anomalies under the Xiaojiang fault,the Qujiang fault and the Shiping-Jianshui fault.By the help of the geochemical study of hot springs,we speculate that the high V_P/V_S anomaly bodies are geothermal fluid rather than molten material.The existence of geothermal fluid may weaken the locking body at the intersection of the Xiaojiang fault,the Qujiang fault and the Shiping-Jianshui fault,which has shown strong locking,so as to reduce the tectonic stress threshold of fault failure.Therefore,the influence of geothermal fluid on the Xiaojiang fault,the Qujiang fault and the Shiping-Jianshui fault deserves special attention.

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备注/Memo

备注/Memo:

收稿日期:2022-06-14.
基金项目:云南省地震局科技专项(2020ZX04).
第一作者简介:曹 颖(1988-),高级工程师,主要从事地震监测工作和地震层析成像研究.E-mail:976242105@qq.com.

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更新日期/Last Update: 2023-03-10