南海北部沿海地区地震活动与发震构造  

Seismicity and Seismogenic Structure in the Northern Coastal Area of the South China Sea

作　　者：夏少红[1,2,3] 林江南 曹敬贺 XIA Shaohong;LIN Jiangnan;CAO Jinghe(CAS Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,Guangdong,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,Guangdong,China;Sanya Institute of Oceanology,SCSIO,Sanya 572100,Hainan,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院边缘海与大洋地质重点实验室,中国科学院南海海洋研究所,广东广州510301 [2]南方海洋科学与工程广东省实验室(广州),广东广州511458 [3]三亚中科海洋研究院,海南三亚572100 [4]中国科学院大学,北京100049

出　　处：《大地构造与成矿学》2022年第3期455-470,共16页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(U1701641,42076071);南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(GML2019ZD0204);海南省重点研发项目(ZDYF2020198)联合资助。

摘　　要：南海北部沿海地区位于华南陆块与南海的交接地带,经历了复杂的地质演化过程,形成了典型的板内地震活动带。本文通过收集研究区固定地震台网记录的地震数据,开展了双差走时地震重定位计算,获得了更为精确的地震震源参数。从地震活动的时空特征可知,南海北部沿海地区地震活动较为活跃,空间上主要形成了几个典型的集群型震群,如南澳岛外海地震群、阳江地震群、新丰江水库地震群以及海南岛岩浆活动地震群等。时间上,研究区每年地震活动的数量与分布模式基本稳定,主要集中在典型的震群区,其他地区零星分布较少的地震。典型震群区地震的分布主要集中在中上地壳(<20 km),下地壳也偶有地震发生。但不同震群区地震的分布形态存在一定差异,南澳岛外海地震分布呈“L”型,以NE向地震活动为主,也存在NW走向的地震分布趋势。阳江地区地震活动主要呈现南、北两个震群,其中南部震群主要呈近E-W向展布,地震活动比北部震群更强烈;北部震群覆盖面积较小,大体以S-N走向展布。新丰江水库地震活动主要分布在贮水盆地的西北部和东南部两个峡谷区,其中约78%的地震集中在水库大坝附近的峡谷区,总体呈NW-SE走向;西北部上游峡谷的震群在2010年以前很少被观测到,而2012年以后却呈明显增加趋势。海南岛地区地震活动主要呈现4个集群,所有集群的震源深度都具有近垂直状的通道分布特征,表明海南地区地震活动与岩浆流体活动存在紧密关联。同时,通过对比分析典型震群区地壳结构和发震构造,我们发现不同震群区发震构造差异性明显,南澳岛外海与珠江口地区的地震主要受NE向和NW向交错断裂以及地壳内部薄弱层和下地壳高速侵入体的控制和影响;新丰江水库地震主要受断裂带内部流体活动和水库静水压力的影响;海南地震活动可能与地幔柱造成�The coastal area of South China belongs to the intersection of the South China Block and South China Sea(SCS),which has undergone a complex geological evolution and formed a typical intraplate seismic activity zone.In this work,the seismic data recorded by the permanent seismic network in the study area are collected and the HypoDD relocation is carried out to get the more accurate seismic source parameters.From the temporal and spatial features of seismic activity,it can be seen that earthquakes in the northern coast of the South China Sea are relatively intense,forming several typical earthquake clusters,such as the Nan’ao Island Offshore earthquake swarms,Yangjiang earthquake swarms,Xinfengjiang Reservoir earthquake swarms,and Hainan Island magma-induced earthquake swarms.The yearly number and distribution pattern of earthquake in the study area are stable,mainly concentrated in the several typical earthquake swarm areas with sporadic earthquake in the other regions.Typical earthquake swarms are primarily distributed in the middle and upper crust depths(<20 km),and fewer occur in the lower crust.However,there are certain different distribution patterns in various earthquake swarm areas.Many seismic events offshore the Nan’ao Island are L-shaped,and most of the earthquakes are gathered to form a NE-trending seismic zone with some distributed in NW trend.The seismic distribution in the Yangjiang area can be divided into the south cluster and the north cluster.The south cluster is ruptured along the near-EW direction,which is obviously more intense than the north cluster that covers a smaller area and generally scatters in the NS direction.In the Xinfengjiang Reservoir area,two canyon areas in the northwest and southeast of the water storage basin are the primary sites of seismic event.About 78%of earthquakes are located in the southeastern canyon area near the dam of the reservoir,showing an overall NW-SE trend;the quake swarm in the upstream canyon of the northwest was rarely observed before 2010,but signif

关 键 词：南海北部 地震活动 地震群 发震构造 重定位 

分 类 号：P65[天文地球—地质学] P511.2