THE INFLUENCE OF THE EARTH'S CURVATURE ON THE LONG-PERIOD MAGNETOTELLURIC SOUNDING METHOD

Abstract

Abstract:

Based on the electromagnetic theory,the forward formula is obtained for the long-period magnetotelluric(LMT)method in a layered spherical earth. The computer program for computing the LMT response is worked out and the forward modeling is completed for some theoretical models. According to the results of forward modeling,we analyzed how the earth's curvature influences the electromagnetic response. The results show that the apparent resistivity will decline and the phase will increase with an increased probing depth. However,the impact of the Earth's curvature can be ignored in the case of one-dimensional base regarding the measurement accuracy of the LMT instrument at present; But with the development of instrument,it is necessary to take the earth's curvature into account in the future.

Key words: long-period magnetotellurics(LMT), electromagnetic response, layered spherical earth model, the earth’s curvature, apparent resistivity, impedance phase

摘要：

基于电磁理论,导出了层状球体大地条件下长周期大地电磁响应的计算公式,编制了计算机程序,并对相应理论模型进行正演计算。根据计算结果,分析了地球曲率对长周期大地电磁测深法视电阻率和阻抗相位的影响。理论模型的计算结果显示,随着探测周期的增大,地球曲率对长周期大地电磁响应的影响逐渐增大,视电阻率曲线会明显下降,阻抗相位曲线逐渐趋于90°; 在一维情况下,对于目前的仪器测量范围可以忽略地球曲率带来的影响,但随着仪器技术的进一步发展,地球曲率对长周期大地电磁测深法的影响不可忽视。

关键词: 长周期大地电磁测深法, 电磁响应, 层状球体模型, 地球曲率, 视电阻率, 阻抗相位

CLC Number:

P631

QIN Qing-yan, LUO Wei, ZHANG Wei. THE INFLUENCE OF THE EARTH'S CURVATURE ON THE LONG-PERIOD MAGNETOTELLURIC SOUNDING METHOD[J]. SEISMOLOGY AND GEOLOGY, 2012, (3): 456-466.

覃庆炎, 罗威, 张伟. 地球曲率对长周期大地电磁测深法的影响[J]. 地震地质, 2012, (3): 456-466.

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