地中电偶极源极低频电磁场的分布与传播特征  

Distribution and propagation characteristics of extremely low frequency electromagnetic field of electric dipole source in the Earth

作　　者：王桥 唐新功[2] 胡文宝[2] WANG Qiao;TANG XinGong;HU WenBao(National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China;Key Laboratory of Exploration Technologies for Oil and Gas Resources,Ministry of Education,Yangtze University,Wuhan 430100,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Beijing Baijiatuan Earth Sciences,National Observation and Research Station,Beijing 100095,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]油气资源与勘探技术教育部重点实验室(长江大学),武汉430100 [3]中国地震局地球物理研究所,北京100081 [4]北京白家疃地球科学国家野外科学观测研究站,北京100095

出　　处：《地球物理学报》2024年第4期1527-1545,共19页Chinese Journal of Geophysics

基　　金：国家自然科学基金(42104159,41574064,42274087);中欧龙计划五期(59308)资助

摘　　要：利用层状大地中偶极源响应的正演算法,计算地中电偶极源激发的极低频地震电磁场并分析其在地球环境下的传播特征.设计了多个水平层状地球模型,分别模拟和展示了深埋地中的电偶极源的响应和空间分布特征.重点分析了含地壳波导+LAI波导模型的高阻大地中,倾斜电偶极源激励响应随观测点的偏移距和垂直位置、激励源深度、地壳波导结构和参数变化时各场量响应的幅频特征.研究表明,用倾斜电偶极源模拟和分析高阻大地中孕震电磁辐射的响应及在大地电磁系统中的传播特性是可行的;模拟的高阻大地中的电磁辐射在地壳波导和LAI波导中均表现有慢衰减或幅值增强特性,但两个波导效应具有不同的频率选择性;高阻大地中的电磁辐射在波导的高阻介质中具有幅值强、衰减慢的特点.建议在高阻地层出露的地表、井中或海底的高阻岩层中以及大气层中布设测站.Based on the forward algorithm of dipole source response in layered earth, the propagation characteristics of an extremely low frequency of seismo-electromagnetic anomalies in the earth's environment are simulated and analyzed. Several typical horizontal layered earth models are designed to simulate and depict the response and spatial distribution characteristics of electric dipole sources underground. The amplitude-frequency characteristics of the excitation response of the inclined electric dipole source in the high resistivity earth with the crustal waveguide plus Lithosphere-Atmosphere-Ionosphere (LAI) waveguide model are analyzed, when the parameters change including the offset and vertical position of the observation point, the depth of the excitation source, and the structure and electromagnetic (EM) parameters of the crustal waveguide. The results show that it is feasible to simulate and analyze the response of seismo-electromagnetic radiation in the high resistivity earth and its propagation characteristics in the magnetotelluric system with the inclined dipole source. The EM radiation in high resistivity earth exhibits slow attenuation or even amplitude enhancement in both crustal waveguide and LAI waveguide, but the two waveguides have different frequency selectivity. It is suggested to set up stations on the surface where the high resistivity formation is exposed, in the well or on seabed with high resistivity rock layer, and the atmosphere.

关 键 词：层状模型 地中电偶极源 极低频电磁场传播特征 岩石圈波导 LAI波导 

分 类 号：P318[天文地球—固体地球物理学] P631[天文地球—地球物理学]