Finite-difference modelling of magnetotelluric fields in two-dimensional anisotropic media
Finite-difference modelling of magnetotelluric fields in two-dimensional anisotropic media
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DOI：
10.1111/j.1365-246x.1997.tb05314.x
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发表时间：
1997-03
影响因子：
2.8
通讯作者：
J. Pek;Tomáš Verner
中科院分区：
文献类型：
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作者：
J. Pek;Tomáš Verner
本文提出了一种在二维各向异性块体结构中进行大地电磁场数值模拟的算法。各个均匀块的电特性由任意对称和正定的电导率张量描述。这个问题导致了一个耦合系统的偏微分方程的电磁场，Ex和H的罢工平行的组件。这些方程的数值近似的有限差分（FD）方法，利用积分插值方法。由于磁分量H在非导电空气中是恒定的，因此在空气层内仅近似电模式的方程。由FD近似得到的线性差分方程组可以以这样的方式排列，即其矩阵是对称的和带限的，并且对于不太大的模型，可以通过高斯消去法求解。该算法适用于模型的情况下，表现出一些非平凡的现象所造成的电各向异性。特别是，详细研究了二维各向异性对大地电磁阻抗与感应箭头关系的影响。
SUMMARY An algorithm for the numerical modelling of magnetotelluric fields in 2-D generally anisotropic block structures is presented. Electrical properties of the individual homogeneous blocks are described by an arbitrary symmetric and positive-definite conductivity tensor. The problem leads to a coupled system of partial differential equations for the strike-parallel components of the electromagnetic field, Ex and H,. These equations are numerically approximated by the finite-difference (FD) method, making use of the integro-interpolation approach. As the magnetic component H, is constant in the non-conductive air, only equations for the electric mode are approximated within the air layer. The system of linear difference equations, resulting from the FD approximation, can be arranged in such a way that its matrix is symmetric and band-limited, and can be solved, for not too large models, by Gaussian elimination. The algorithm is applied to model situations which demonstrate some non-trivial phenomena caused by electrical anisotropy. In particular, the effect of 2-D anisotropy on the relation between magnetotelluric impedances and induction arrows is studied in detail.