小地震精定位与层析成像揭示的邢台地震区深部构造特征  

DEEP STRUCTURAL CHARACTERISTICS IN THE XINGTAI SEISMIC ZONE REVEALED BY PRECISE RELOCATION OF SMALL EARTHQUAKES AND TOMOGRAPHY

作　　者：刘亢[1,2] 杨婷 李红光[1] 房立华[3,4,5] 宋键[6] LIU Kang;YANG Ting;LI Hong-guang;FANG Li-hua;SONG Jian(National Earthquake Response Support Service,Beijing 100049,China;Hebei Key Laboratory of Earthquake Dynamics,Sanhe 065201,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Key Laboratory of Earthquake Source Physics,China Earthquake Administration,Beijing 100081,China;Institute of Disaster Prevention,Sanhe 065201,China;Ludong University,Yantai 264025,China)

机构地区：[1]中国地震应急搜救中心,北京100049 [2]河北省地震动力学重点实验室,三河065201 [3]中国地震局地球物理研究所,北京100081 [4]中国地震局震源物理重点实验室,北京100081 [5]防灾科技学院,三河065201 [6]鲁东大学,烟台264025

出　　处：《地震地质》2023年第6期1328-1348,共21页Seismology and Geology

基　　金：国家重点研发计划项目(2021YFC3002104);河北省地震动力学重点实验室开放基金(FZ212101)共同资助。

摘　　要：1966年河北邢台M_(S)7.2地震发生后小地震持续不断,为开展该地区的深部构造研究提供了便利条件。文中基于河北省地震台网1991—2021年间的观测数据,采用双差定位法获得了邢台及其邻区9644次地震的精定位结果,清晰地刻画出深部断裂的空间形态;结合华北流动地震台阵2006—2008年的观测数据,采用38578个P波到时数据,获得了研究区高分辨率走时层析成像结果。研究表明:研究区的地壳速度结构存在较强的横向不均匀性,新河断裂与元氏断裂之间的上地壳存在明显的低速异常,中下地壳存在高速异常,邢台地震位于高、低速异常体交界处,该位置具备积累大量应变能的介质条件,易发生破裂,释放应力;邢台震区小地震密集带与高、低速异常体东边界的总体展布趋势比较一致,推测沿高、低速体东边界展布的深、浅部断裂已上下贯通,速度异常体的边界位置同样也是速度变化相对强烈的部位,易发生地震破裂;综合多种地震、地质调查成果,揭示出邢台震区下方存在一条贯通整个地壳的深大断裂,倾向SE,上断点位于东汪附近,邢台地震促使深浅部的先存断裂上下贯通。From March 8 th to 29 th,1966,five earthquakes(M≥6)occurred in the Xingtai area,with the M S6.8 earthquake on March 8 th and the M S7.2 earthquake on March 22 nd being the most severely damaged.The Xingtai earthquake resulted in over 8000 deaths and the economic losses up to 1 billion yuan.The Xingtai earthquake has opened the scientific practice of earthquake prediction in China and is a milestone in the development of earthquake science in China.Based on previous research results,there is a deep fault beneath the Xingtai earthquake area,which is the energy source of earthquakes,while there is a relatively independent fault system in the shallow part,which is generally recognized by scholars.However,the divergence regarding the seismogenic structure of the Xingtai earthquake mainly focuses on the unclear coupling relationship between the deep and shallow structural systems in the seismic area.The structural relationship between deep seismic faults and the shallow Xinhe Fault system requires new evidence to determine.In addition,previous scholars have proposed the viewpoint of“Newly generated Fault”,which can better explain the rupture characteristics of the Xingtai earthquake,but it still needs to be supported by the inversion results of the seismic rupture process based on the three-dimensional crustal fine structure.There are many small earthquakes in the Xingtai area.Deep structural information can be obtained using small earthquake data.Especially after 2009,the significant improvement in earthquake positioning accuracy in North China has made it possible to obtain new insights into deep structures.By locating small earthquakes,the spatial distribution and motion characteristics of faults are characterized,and seismic travel time tomography reveals the deep crustal velocity structure characteristics of the earthquake area.Combining previous geophysical exploration results,conducting deep and shallow structural analysis is of great significance for studying the spatial distribution,motion characteristic

关 键 词：邢台地震 小地震精定位 层析成像 深部构造 滑脱构造 

分 类 号：P315.2[天文地球—地震学]