SEISMOLOGY AND GEOLOGY ›› 2016, Vol. 38 ›› Issue (4): 922-936.DOI: 10.3969/j.issn.0253-4967.2016.04.010

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APPARENT RESISTIVITY TEMPORAL VARIATION CHARAC-TERISTICS AFFECTED BY THE FIXED DISTURBANCE SOURCE ON SURFACE OF MEASURING AREA

XIE Tao, LU Jun   

  1. China Earthquake Networks Center, Beijing 100045, China
  • Received:2015-10-19 Revised:2016-05-14 Online:2016-12-20 Published:2017-01-20

地表固定干扰源影响下地电阻率观测随时间变化特征分析

解滔, 卢军   

  1. 中国地震台网中心, 北京 100045
  • 作者简介:解滔,男,1986年生,2011年毕业于中国地震局兰州地震研究所固体地球物理学专业,获理学硕士学位,助理研究员,目前主要从事地震电磁学及卫星热红外遥感应用研究,电话:010-59959144,E-mail:xtaolake@163.com。
  • 基金资助:

    中国地震局监测预报司震情跟踪定向工作任务(2016020402)资助

Abstract:

Current leakage,metallic conductor,and local anomalous resistivity body are main disturbance sources which affect the successive observation of apparent resistivity in stations,besides the observing system failure.We construct a finite element model using a 3-layered horizontal medium to discuss the dynamic characteristics of disturbances caused by metal conductor and local anomalous resistivity body in the measuring filed.The numerical results show that low resistivity source which is located in areas where the sensitivity coefficient is positive will cause decline on apparent resistivity observation.While low resistivity source will cause increase when it is located in areas where the sensitivity coefficient is negative.Disturbance caused by high resistivity source is opposite to the one from low resistivity source.The general dynamic feature of disturbance is that the disturbance amplitude increases as the resistivity of shallow layer decreases,while the amplitude declines when the shallow layer's resistivity increases.For the measuring direction which has normal annual variation form,low resistivity source which is located in area where the sensitivity coefficient is positive will increase the annual variation amplitude,while it will reduce annual amplitude when it is in a negative sensitivity coefficient area.Annual amplitude changes caused by high resistivity source are opposite to the changes caused by low resistivity source.For the measuring direction which has abnormal annual variation form,dynamic annual feature is opposite to the one in direction of normal annual variation form.If the dynamic feature is opposite to the annual variation and disturbance amplitude is also greater than annual amplitude,the annual variation will change direction.Disturbance amplitude from metallic conductor is affected by the resistivity and cross-section area,the lower of the resistivity and the larger of the cross-section area,the greater of the disturbance amplitude.

Key words: earthquake, apparent resistivity, disturbance, dynamic feature, anomalous resistivity body, metallic conductor

摘要:

在水平层状介质模型下,采用有限元数值计算方法建立三维模型,分析了地电阻率测区中位于地表的金属导线和局部电性异常体对观测产生的干扰形态和幅度随时间的变化特征。分析结果显示:1)低阻干扰源位于影响系数为正的区域时,将引起地电阻率观测值的下降变化,位于影响系数为负的区域时,将引起观测值的上升变化,高阻干扰源对观测的影响与之相反;2)地表干扰源影响的动态特征表现为,在浅层介质电阻率较低时对观测的干扰幅度要大于浅层介质电阻率较高时;3)对于正常年变的测道,低阻干扰源位于影响系数为正的区域时引起年变幅度增大,位于影响系数为负的区域时引起年变幅度减小,高阻干扰源对年变形态的影响与之相反;对于反常年变的测道,干扰源对年变形态的影响则与对正常年变测道的影响相反;4)金属导线对观测的干扰幅度受自身电阻率和横截面积影响:电阻率越低干扰幅度越大;有效横截面积越大干扰幅度越大。

关键词: 地震, 地电阻率, 干扰, 动态特征, 电性异常体, 金属导线

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