Preliminary Results of the Seismicity Monitoring Experiment around the 2019 Mw5.4 Earthquake Epicenter in the Central South China Sea Basin  

作　　者：Wenfei Gong Aiguo Ruan Xiongwei Niu Zhenjie Wang Pingchuan Tan Xiaodong Wei Wei Wang Zhengyi Tong Liqun Cheng Fansheng Kong Shaoping Lu Jianke Fan Weiwei Ding Jinyao Gao Chunguo Yang Jiabiao Li 

机构地区：[1]School of Oceanography,Shanghai Jiaotong University,Shanghai 200240,China [2]Key Laboratory of submarine Geosciences,Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou 310012,China [3]Zhejiang Earthquake Administration,Hangzhou 310013,China [4]School of Earth Sciences,Zhejiang University,Hangzhou 310027,China [5]Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,China [6]School of Earth Sciences and Engineering,Sun Yat-sen University,Zhuhai 519082,China [7]Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China

出　　处：《Journal of Earth Science》2024年第1期212-220,共9页地球科学学刊（英文版）

基　　金：jointly supported by the National Natural Science Foundation of China(Nos.42076047,41890811)。

摘　　要：On September 5,2019,a moderate earthquake of Mw5.4 unexpectedly occurred in the apparently quiescent central basin of the South China Sea.We immediately carried out a seismicity monitoring experiment around the epicenter by using broadband ocean bottom seismometers(OBS)for the following three scientific targets.The first is knowing the earthquake seismogenic mechanism,fault structure and further development.The second is finding the role of the residual spreading ridge playing in earthquake processes and further revealing the deep structures of the ridge directional turning area.The third is confirming the existence and significance of the so called“Zhongnan fault”.This paper reports the preliminary results of the first phase experiment.Five OBSs were deployed for seismicity monitoring with a duration of 288 days,but only three were recovered.Micro-earthquakes were firstly detected by an automatic seismic phase picking algorithm and then were verified by analyzing their seismic phases and time-frequency characteristics in detail.A total of 21,68 and 89 microearthquakes were picked out from the three OBSs respectively within the distance of 30 km.The dominant frequency of these micro-earthquakes is 12-15 Hz,indicating tectonic fracturing.During the first two months after the mainshock the seismicity was relatively stronger,and micro-earthquakes were still occurring occasionally till the end of observation,indicating the epicenter area is active.We used Match&Locate method to locate 57 micro-earthquakes preliminarily.Their spatial distribution shows that the seismicity is developed mainly along the NE direction roughly parallel to the residual ridge with depth variations between 10-20 km.

关 键 词：South China Sea microseismic monitoring EARTHQUAKES FAULT broadband OBS 

分 类 号：P714[天文地球—海洋科学]