郯庐断裂带南段对近地表大地电流的分异性  

DIFFERENTIATION DIRECTION OF TELLURIC CURRENTS IN THE SOUTHERN SECTION OF THE TANLU FAULT ZONE

作　　者：章鑫 杜学彬[2] ZHANG Xin;DU Xue-bin(Key Laboratory of Earthquake Monitoring and Disaster Mitigation Technology,Guangdong Earthquake Agency,Guangzhou 510070,China;Lanzhou Institute of Seismology,CEA,Lanzhou 730000,China)

机构地区：[1]广东省地震局,地震监测与减灾技术重点实验室,广州510070 [2]中国地震局兰州地震研究所,兰州730000

出　　处：《地震地质》2020年第4期909-922,共14页Seismology and Geology

基　　金：中国地震局地震科技星火计划项目(XH18035Y);国家自然科学基金(41374080)共同资助。

摘　　要：文中以渤海湾以南的郯庐断裂带南段为研究对象,应用华北地区27个地电场台站的观测数据,计算大地电流密度矢量和流线场,并获取流线场的散度和涡度。结果显示:郯庐断裂带南段对表层大地电流的流向有分异作用,在郯庐断裂带两侧的表层大地电流矢量方向相反,东侧流向为NW向,西侧流向为SW或W向;断裂带对流线场的散度和涡度也存在分异作用,散度和涡度的正(负)最大值主要出现在断裂带附近的浅层高导区域。文中通过模拟断裂带两侧的磁感应电流,并与前人的研究进行对比,建立了断裂带分异作用的解释模型。该模型显示电流方向的差异与郯庐断裂带南段深部的电性结构相关,电性差异是近地表大地电流方向分异的主要原因。研究断裂带对表层电流的分异现象对于理解深部电性差异具有参考意义。The Tancheng-Lujiang Fault is an important tectonic boundary in eastern China.The southern part of the Tancheng-Lujiang Fault is located south of Baohai Bay,which is an area with a dense population and frequent economic activities.It is worth conducting an in-depth study on the southern section of the fault,especially in the aspect of geophysical exploration and seismicity analysis.Electrical structure detection is an important way to interpret the structural activity of the fault.It can also analyze and explore the influence of the fault on the physical properties of both sides of the fault based on the geoelectrical observation data.In the study area,there are densely distributed stations of geoelectrical observation,including 27 fixed stations distributed along the fault zone from the southern Baohai Bay to Nanjing,Jinagsu Province.The continuous observations and recording of these stations provide a favorable condition for studying the tectonic activity of Tancheng-Lujiang Fault.In the long-term observation of geoelectric observation network,the geoelectric field measurements of long-and short-spacing measuring tracks in the same direction at the same station vary significantly because of the effect of long-term stability of the observation system and the environment near the electrodes.Also,the data curve changes complicatedly and seems to be in a mess.However,there are three basic facts of observation existing in the geoelectric field change:1)The variation amplitude of the geoelectric field changes observed on the long-and short-spacing measuring tracks in the same direction at the same station(including tidal response changes and the rapid change events such as short periods or pulses)is the same or very close;2)The Ex and Ey components at the same station always show the same variation in the same time period,or the opposite,which is related to the anisotropy of the medium under the station;3)The rapid changes of the minute values of the geoelectric field observed at different stations are synchronous in

关 键 词：郯庐断裂带南段 大地电流 分异作用 数值模拟 

分 类 号：P315.722[天文地球—地震学]