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[1]HUANG Ya,CHEN Jia,JIN Mingpei,et al.Seismic Characteristics in the Meta-instability Stage of the 2021 Yangbi,Yunnan MS6.4 Earthquake[J].Journal of Seismological Research,2021,44(03):357-366.

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Seismic Characteristics in the Meta-instability Stage of the 2021 Yangbi,Yunnan M_S6.4 Earthquake

Journal of Seismological Research[ISSN 1000-0666/CN 53-1062/P] Volume: 44 Number of periods: 2021 03 Page number: 357-366 Column: Public date: 2021-10-20

Title:: Seismic Characteristics in the Meta-instability Stage of the 2021 Yangbi,Yunnan M_S6.4 Earthquake

Author(s):: HUANG Ya; CHEN Jia; JIN Mingpei; LI Xiaobin; CHA Wenjian; WANG Jun; LI Sihai; (Dali Center of China Earthquake Science Experimental Site,Dali 671000,Yunnan,China)

Keywords:: fault meta-instability stage; synergism process; seismicity; the Yangbi M_S6.4 earthquake; meta-instability dense array; northwest Yunnan

CLC:: P315.72

DOI:: -

Abstract:: In this paper,using the observation data of the dense network composed of meta-instability array and 10 fixed stations,we carry out the temporal and spatial scanning of seismic parameters such as frequency,total fault area,and b-value of the complete magnitude before the Yangbi M_S6.4 earthquake in northwest Yunnan province.We find that there are obvious common characteristics such as increasing frequency,increasing total fault area and low b-value before the instability of the M>4.0 earthquakes in the study area.The coordinated evolution of faults with small-earthquake activity as the indication before the Yangbi M_S6.4 earthquake can be roughly divided into three stages:①the period from May to December 2020,in which strain-release points appeared,and the frequency of small earthquakes increased slowly; ②the period from January to May 17,2021,in which the strain-release points increased and extended,and the frequency of small earthquakes increased,and the number of M>3.0 earthquakes increased significantly,and their epicenters migrated to the epicenter of the main earthquake.At the end of the stage,the strain-release points expanded into a belt.③the period from May 18 to 21,2021,in which the strain-release points linked together and even overlapped.And small and medium earthquakes increased rapidly,and the M>4.0 earthquakes concentrated.We conclude that the meta-instability process should consist of the static phase(from January to May 17,2021),and the dynamic phase(from May 18 to 20,2021).Finally we discuss the causes of the meta-instability and the questions in the division of the meta-instability process.

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Last Update: 2021-10-20