摘要
在地震电磁学研究中,电流在地下的流动特征与构造关系是一个非常重要的问题.大范围观测站的分布和强电流源存在的格局为我们研究这个问题提供了机会.本文通过对青岛换流站接地极向地下注入2100～3004A大电流时华北东部地区21个地电场台站观测的研究,深入认识了地电场信号变化实质.研究表明:①沿着郯庐断裂带方向、跨过郯庐断裂带西南方向、跨过郯庐断裂带北西方向能够记录到地电流信号的特征变化非常大,存在着明显方向性特征和"穴位"现象.②注入大地的电流强度越大,则在观测点记录到的地电流信号强度也越强.③本文研究区域里地电场信号的均匀度并不遵循均匀介质条件下的一般规律,说明地下介质电性非均匀性和各向异性特征明显.④大电流注入地下时能够较正确地反映信号源方位的台站较少,只有安丘台、大山台和新沂台所观测到的方位线可用于确定信号源的位置.本文从点电流源与台站测线布局构成的装置系统、大区域介质非均匀性、台站测区以及附近地区的介质细结构的影响三个方面,通过数值模拟,对上述特征进行了较深入的分析和解释.
In the study of seismo-electromagnetics,the relationship between the flowing characteristics of telluric current and the geological structure is a very important problem.The arrangement of broad distribution of many geoelectric field stations and powerful current injected into the underground supply us a golden opportunity to study the scientific problem.In this paper,by studying the signals originated from grounding electrode 2100～3004 Acurrent of Qingdao converter station that were recorded at twenty one geoelectric field stations in the east Huabei area,we could recognize the variation features of geoelectric field in a deepgoing way.The study shows that①along the directions of the Tan-Lu fault and the southwest beyond the fault zone as well as the northwest of it the telluric current signals present extremely different varying characteristics,and there are obvious directionality feature and phenomenon of sensitive site;② The larger the current intensity of the source is,the higher the signal strength recorded at observatory stations is.When the current intensity of the source changed from 2100Ato 3004A the increase rate of the signals recorded on the long dipole is different from that on short dipole at many stations;③ The uniformity degree of the geoelectric field in the area do not follow the regular patterns of homogeneous medium,which illustrates that the characteristics of inhomogeneous medium and anisotropy are obvious at many stations in the area;④ There are seldom stations that could be used to determine the direction of the source,but the azimuth obtained at Aqiu,Dashan and Xinyi stations could be used to locate the source site when a great current was injected.Thinking of the influences of the three factors,i,e,.the device system consisting of a point source and the dipole distribution of a station,heterogeneity of medium in a large area,as well as fine structure of the medium underground at a station,this paper makes a deep analysis and explanation of the characteristics mentioned above by using the numerical simulation.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2014年第2期518-530,共13页
Chinese Journal of Geophysics
基金
中国地震局星火项目(XH12016)
上海市科委科研计划项目(12231202700)
华北地区强震强化监视跟踪工作资助
关键词
大电流
地电场信号
信号源定位
地震电信号
Great current emission
Signal of geoelectric field
Location of signal source
Seismic electric signal
