3-DIMENSIONAL INDUCTION IN A NONUNIFORM THIN SHEET AT THE SURFACE OF A UNIFORMLY CONDUCTING EARTH

Summary. A new method for solving problems in three‐dimensional electromagnetic induction in which the Earth is represented by a uniformly conducting half‐space overlain by a surface layer of variable conductance is presented. Unlike previous treatments of this type of problem the method does not require the fields to be separated into their normal and anomalous parts, nor is it necessary to assume that the anomalous region is surrounded by a uniform structure; the model may approach either an E‐ or a B‐polarization configuration at infinity. The solution is expressed as a vector integral equation in the horizontal electric field at the surface. The kernel of the integral is a Green's tensor which is expressed in terms of elementary functions that are independent of the conductance. The method is applied to an illustrative model representing an island near a bent coastline which extends to infinity in perpendicular directions. Copyright © 1979, Wiley Blackwell. All rights reserved