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Title:: Accurate Location of the 2020 Dongchuan,Yunnan M_L4.2 Earthquake Sequence

Author(s):: GAO Fanghong; LIU Zhikun; GENG Chuantao; (School of Geophysics and Information Technology,China University of Geosciences,Beijing 100083,China)

Keywords:: earthquake location; microseismic detection; the Xiaojiang Fault Zone; double-difference earthquake location; pull-apart basin; Dongchuan M_L4.2 earthquake

摘要:: 利用云南东川地区10个宽频带流动台站的连续波形数据,采用基于深度学习的自动震相拾取方法和震相关联技术,对2020年东川M_L4.2地震序列分别进行绝对定位和相对定位,获得了该地震序列的高精度地震定位结果,得到东川M_L4.2地震序列的212个余震事件,约为中国地震台网目录给出的余震数目的5倍,丰富了M_L≤3.0余震; 精定位结果表明东川M_L4.2主震震源深度为5.19 km,余震震源深度集中在3～6 km,余震序列分布长轴呈NNE向展布; 此次地震发生在小江断裂带西支,发震构造与乌龙拉分盆地的构造演化有关。

Abstract:: Selecting the continuous waveform data from 10 temporary broadband seismic stations in Dongchuan,Yunnan Province,and using the automatic seismic phase detection and correlation based on deep learning,we conduct absolute and relative locations of the July 8th,2020 Dongchuan M_L4.2 earthquake sequence,and obtain high-resolution results:the M_L4.2 earthquake sequence contains 212 events,about five times of the events from the catalogue of China Earthquake Networks Center,enriching the M_L<3.0 aftershocks.The focal depth of the M_L4.2 mainshock is 5.19 km and the aftershock sequence concentrates in the depth of 3—6 km.The Long axis of the aftershock zone is in the NNE direction.The earthquake sequence occurs in the west branch of the Xiaojiang Fault Zone and its seismogenic structure may be related with the tectonic evolution of the pull-apart Wulong Basin.