郯庐断裂渤海湾北段地震活动及其指示意义  

Seismicity of the northern section of the Tanlu fault zone in the Bohai Bay and its implications

作　　者：陈瑛 梁晓峰[3,4] 闫宏芳 姜明明[1,2,5] 艾印双 CHEN Ying;LIANG XiaoFeng;YAN HongFang;JIANG MingMing;AI YinShuang(Key Laboratory of Earth and Planetary Physics,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Institutions of Earth Science,Chinese Academy of Sciences,Beijing 100029,China;CAS Center for Excellence in Tibetan Plateau Earth Sciences,Beijing 100101,China;Guangdong Earthquake Agency,Guangzhou 510070,China)

机构地区：[1]中国科学院地质与地球物理研究所,地球与行星物理重点实验室,北京100029 [2]中国科学院大学地球科学学院,北京100049 [3]中国科学院地质与地球物理研究所,岩石圈演化国家重点实验室,北京100029 [4]中国科学院地球科学研究院,北京100029 [5]中国科学院青藏高原地球科学卓越创新中心,北京100101 [6]广东省地震局,广州510070

出　　处：《地球物理学报》2020年第7期2566-2578,共13页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41474040,41125015)资助.

摘　　要：郯庐断裂渤海湾北段纵贯辽宁省,现今仍然活动,1975年海城M_S7.3地震就发生在该断裂系统上.利用2005年5月至2006年4月布设的渤海湾流动地震台阵观测数据,结合辽宁省固定地震台网数据,重新拾取了780个区域小地震,并使用双差地震定位方法获得了546个地震事件的定位结果.通过自助法得到双差定位的平均水平误差和深度误差分别为1.5和1.9km.结果显示在观测周期内,郯庐断裂渤海湾北段主断裂地震不活跃,但是主断裂东侧的海城河断裂和太子河断裂小震沿断裂呈条带状密集分布.利用gCAP(general Cut and Paste)方法计算了区域地震震源机制解,选取出4个可信的震源机制解;综合前人已有结果,认为研究区的小地震震源机制主要以走滑与正断为主,与区域构造应力场吻合良好.海城河和太子河断裂的地震活动深达中下地壳,结合热流数据和岩石物理实验,推测研究区中下地壳由干燥的镁铁质岩石组成.The northern section of the Tanlu fault zone,extending through Liaoning Province,is considered active at present,at which the 1975 M S7.3 Haicheng earthquake occurred.In this study,we re-pick up 780 events around this fault and then from which relocate 546 small ones using a double-difference relocation method(HypoDD)based on the seismic data recorded by Bohai Bay seismic network and Liaoning Provincial Seismic Network from May 2005 to April 2006.The horizontal and vertical location uncertainties are 1.5 and 1.9 km,respectively.The location results show that the seismicity in the main fault of this section is not active.While the banded dense distributions of quakes are present along both the Haichenghe fault and the Taizihe fault east of the main fault in the Bohai aforementioed.General Cut and Paste method(gCAP)is used to calculate the focal mechanism solutions of these events,from which four solutions are reliable.In combination with previous relevant studies,the focal mechanisms of the small earthquakes in the study region are dominated by strike-slip and normal faulting,which is consistent with the regional tectonic stress field.The focal depths on the Haichenghe fault and the Taizihe fault extend downward to the mid-lower crust.Combining with heat flow data and petrophysical experiments,this work speculates that the middle and lower crust beneath study region is likely composed of dry mafic rocks.

关 键 词：地震定位 震源机制解 海城河断裂 太子河断裂 

分 类 号：P315[天文地球—地震学]