人工源地电场“选择性”现象研究  

Selectivity phenomenon of artificial-source geoelectric field

作　　者：赵文舟[1,2] 马钦忠 李伟[1,2] 周江南 ZHAO WenZhou;MA QinZhong;LI Wei;ZHOU JiangNan(Earthquake Administration of Shanghai Municipality,Shanghai 200062,China;ShanghaiSheshan National Geophysical Observatory,Shanghai 200062,China)

机构地区：[1]上海市地震局,上海200062 [2]上海佘山地球物理国家野外科学观测研究站,上海200062

出　　处：《地球物理学报》2022年第5期1742-1752,共11页Chinese Journal of Geophysics

基　　金：上海市科委科研计划项目(16dz1205800);上海佘山野外科学观测站项目(2021SSY03);地震科技星火计划(XH20019)共同资助.

摘　　要：地震电信号的“选择性”现象是地电学中非常重要的特征.地电信号的“选择性”现象普遍存在:上海浦东张江台观测不到源自其西南方向三个接地极上千安培入地大电流的附加地电场,而能够观测到其正南方向接地极入地大电流的附加地电场;山东地区邹城台和乳山台无法接收到青州接地极上千安培入地大电流.通过大地电磁测深手段探明了张江台出现该现象的主要原因在于其西南方向信号源至观测台之间地下存在着巨大的高阻体;其正南方向观测台至信号源之间地下以中低阻体和低阻体为主.上述大地电磁测深资料和断层解释为张江地电场台站观测特征的机理进行了很好阐释,解释了地震电信号在大区域范围传播过程中由于大尺度地下电性结构复杂性带来的影响,为深入认识地震电信号“选择性”现象提供了直接的勘探依据.Selectivity of seismic electrical signals is a very important feature of geoelectric field.The phenomenon of geoelectric signal selectivity is ubiquitous:at Zhangjiang station in Shanghai,additional geoelectric signals of thousands of amperes from three grounding electrodes of High Voltage Direct Current Transmission in the southwestern direction cannot be observed,but additional geoelectric signals from the electrode in the southern direction are observed;at Zoucheng and Rushan stations in Shandong province,additional geoelectric signals of thousands of amperes from the Qingzhou grounding electrode cannot be observed.With magnetotellurics(MT),it is proven that the main reason for this phenomenon at Zhangjiang is that a huge high-resistance body exists underground between the signal sources in the southwestern direction and the observation station,and the subsurface between the observation station and the signal sources in the southern direction is dominated by low and medium resistance bodies.MT sounding data and fault characteristics provide a good explanation of additional geoelectric field signal transmission at Zhangjiang station.Large-scale underground effects of electrical structure complexity show that the selectivity phenomenon for recognizing seismic signals has a direct exploration basis.

关 键 词：大地电磁测深 电性结构 断层解释 “选择性”现象 上海和山东地区 

分 类 号：P319[天文地球—固体地球物理学] P631[天文地球—地球物理学]