利用大地电磁密集阵列研究蚌埠地震构造环境  

Study on the seismotectonic environment in Bengbu city using the dense magnetotelluric array

作　　者：蔡军涛 陈小斌 方良好 戚浩[2] 王培杰 张赟昀 刘钟尹 谢兴兵[4] 周磊[4] CAI JunTao;CHEN XiaoBin;FANG LiangHao;QI Hao;WANG PeiJie;ZHANG YunYun;LIU ZhongYin;XIE XingBing;ZHOU Lei(National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China;Anhui Earthquake Agency,Hefei 230031,China;Institute of Geology,China Earthquake Administration,Beijing 100029,China;College of Geophysics and Petroleum Resource,Yangtze University,Wuhan 430100,China)

机构地区：[1]应急管理部国家自然灾害防治研究院,北京100085 [2]安徽省地震局,合肥230031 [3]中国地震局地质研究所,北京100029 [4]长江大学地球物理与石油资源学院,武汉430100

出　　处：《地球物理学报》2023年第2期638-658,共21页Chinese Journal of Geophysics

基　　金：国家重点研发计划项目(2017YFC1500204-0002);中国地震局地震科技星火计划项目(XH20027Y);蚌埠市活动断层探测与地震危险性评价项目(ZB202003052)资助。

摘　　要：本文基于蚌埠及邻区100个高质量测点组成的宽频带大地电磁密集阵列数据,首先利用相位张量和阻抗张量统计成像技术定性分析了研究区构造维性和电性结构特征,然后采用多重网格法结合多次迭代重构的三维反演技术获得了其精细可靠的三维电阻率结构.结果显示蚌埠隆起南、北部电性结构存在显著差异,支持其南部和北部存在不同的构造演化和变形机制的观点.蚌埠隆起内部存在多个切割高阻异常体、与断裂带对应的低阻条带,其中下地壳存在高导异常.综合分析推断,该中下地壳高导异常为流体渗入到先存多条交切断层的破碎带所致,深部物质对蚌埠隆起区构造变形的作用不显著.本文研究认为蚌埠及其邻近地区具备强震孕育的深部结构环境,但该区域构造变形驱动机制有待探讨.In this study, broadband magnetotelluric(MT) dense array data composed of 100 sites with high quality was recorded in Bengbu and adjacent areas. We analysed the dimensionality and characteristics of the electrical structure with the phase tensor and statistical imaging method of the impedance tensor. A fine and reliable 3D resistivity structure was obtained using the 3D inversion method combined with a multi-grid algorithm and multiple iterative reconstruction inversion technology. The results show significant differences in electrical structure between the southern and northern parts of the Bengbu uplift, which support the view that there are different tectonic evolution and deformation mechanisms in the Bengbu uplift. Inside the Bengbu uplift, several low-resistivity belts, cutting high-resistivity anomalies, correspond to the fault zone. A high conductivity anomaly exists in the middle to lower crust of the Bengbu uplift. Comprehensive analysis infers that fluids penetrating the fractured zone caused by cutting several faults produce this high conductivity anomaly in the middle to lower crust. The deep material has no significant effect on the tectonic deformation of the Bengbu uplift. Our study suggests that Bengbu and its adjacent areas have a deep structural environment for strong earthquakes. However, the driving mechanism of tectonic deformation in this area remains to be discussed.

关 键 词：蚌埠 大地电磁 三维电性结构 城市活断层 郯庐断裂带 

分 类 号：P315[天文地球—地震学] P319[天文地球—固体地球物理学]