起伏地形条件下二维大地电磁各向异性正演

The forward modeling of two-dimensional anisotropic magnetotelluric with topography

在大地电磁资料处理和解释中,大地电磁的各向异性正演一直是国内、外研究的前沿课题。这里首先从麦克斯韦方程组出发,得出各向异性介质二维大地电磁场的边值问题以及等价的变分问题,进而对计算区域进行完全非结构化三角形剖分,在单元内采用线性插值,将变分方程转化成线性方程组,求解出有限单元法数值解,获得各向异性介质下的电磁场值。讨论了电性主轴与笛卡尔坐标轴之间的夹角以及地形的起伏变化对视电阻率和相位值的影响,结果表明:起伏地形条件下,TE和TM两种极化模式的视电阻率和相位值都会受到影响,且TM模式受地形影响较大;由于介质的各向异性,视电阻率和相位断面图出现明显不同于各向同性的形态,导致横向分界面模糊。

In the interpretation of magnetotelluric data processing, the phenomenoimportant factors that cannot be ignored. The forward modeling of anisotropic magnetotelluric has always been the forefrontsubject at home and abroad. In this paper , we given the boundary value problems and its corresponding variational problem of magnetotelluric in 2D anisotropic geoelectric section from the Maxwell＇s equations. A triangular grid is used to discretize the calculation area , and linear interpolation is used at each triangular to compute the numerical solution with tinite element method obtained the apparent resistivity and phase values. In the subsequent section we discuss the effect of the angle between the elec-trical spindle and Cartesian coordinate axis and topography.