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[1]CAO Ying,FU Hong,QIAN Jiawei.Characteristics of 3D Velocity Structure in the Arcuate Tectonic Belt of Southeastern Yunnan[J].Journal of Seismological Research,2023,46(02):245-260.[doi:10.20015/j.cnki.ISSN1000-0666.2023.0024 ]

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

Journal of Seismological Research[ISSN 1000-0666/CN 53-1062/P] Volume: 46 Number of periods: 2023 02 Page number: 245-260 Column: Public date: 2023-03-10

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

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)

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

CLC:: P315.2

DOI:: 10.20015/j.cnki.ISSN1000-0666.2023.0024

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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Last Update: 2023-03-10