起伏地形条件下层状介质的视电阻率计算及其在地电前兆分析中的应用

CALCULATION OF APPARENT RESISTIVITY UNDER THE CONDITION OF UNDULATE TOPOGRAPHY AND APPLICATIONS IN THE ANALYSIS OF GEOELECTRIC PRECURSOR

本文以二维层状介质模型为基础利用边界单元法,对地形起伏所引起的视电阻率变化进行了数值模拟,探讨了水平层状介质表层存在不规则地形条件下地电阻率的理论计算方法,并讨论了地形对地电前兆复杂性的影响。结果表明,起伏较大的地形变化对视电阻率相对变化量中的深层电阻率变化有减小作用,这就降低了地电观测资料中包含的深层电性信息的比例,因而对突出地电观测资料中孕震变化的成份是不利的。

This paper deals with the numerical simulation of the changes of apparent resistivity caused by topographic undulation based on the model of 2 D layered medium by using the boundary element method, and the general calculating method of apparent resistivity under the condition of abnormal surface topography in the horizontal layered medium and the influence of topography on geoelectrie precursor are also discussed. The results show that the bigger the changes in topography, the less the information in apparent resistivity changes from deep depth. Thus, the proportion of precursory infor mation could be reduced. From this point of view, big undulation in topography could be unfavorable for geoelectrie resistivity monitoring.