Magnetotelluric response on vertically inhomogeneous Earth
Magnetotelluric response on vertically inhomogeneous Earth
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DOI：
10.1029/jb086ib04p03027
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发表时间：
1981-04
影响因子：
--
通讯作者：
D. Kao
中科院分区：
文献类型：
--
作者：
D. Kao
研究了电阻率随深度线性变化的非均匀大地中的大地电磁响应。在这样的介质中的水平电场和磁场的修正贝塞尔函数的条款。计算了（1）非均匀半空间，（2）均匀层覆盖的非均匀半空间，（3）夹在两个均匀层之间的过渡区的非均匀层的阻抗和视电阻率。结果以图形方式呈现，并与Cagniard模型和均匀多层模型进行了比较。在电阻率随深度减小的情况下，上述非均匀模型的结果与Cagniard两层模型的结果相似，等价性为h1 c = h1，+ ρ1/α。在电阻率随深度增加的情况下，上述非均匀模型的结果通常不能用Cagniard两层模型来拟合，但如果各层参数选择得当，可以用均匀多层模型来拟合。阻抗倒数作为频率的函数比视电阻率更有助于确定上覆均匀层的增加速率α和厚度h1。
Magnetotelluric response in an inhomogeneous earth having resistivity varying linearly with depth is investigated. Horizontal electric and magnetic fields in such a medium are given in terms of modified Bessel functions. Impedance and apparent resistivity are computed for (1) an inhomogeneous half-space, (2) an inhomogeneous half-space overlain by a homogeneous layer, and (3) an inhomogeneous layer as a transition zone sandwiched between two homogeneous layers. Results are presented graphically and are compared with those of Cagniard models and with homogeneous multilayer models. In the case of resistivity decreasing with depth, the results of the above inhomogeneous models are similar to that of Cagniard two-layer models, with the equivalence of h1c = h1, + ρ1/α. In the case of resistivity increasing with depth the results of the above inhomogeneous models can not usually be fitted with Cagniard two-layer models but can be fitted with homogeneous multilayer models if the parameters of the layers are favorably chosen. The reciprocal impedance as a function of frequency is more useful than the apparent resistivity for determining the rate of increase α and the thickness h1 of an overlying homogeneous layer.