EFFECT OF RELIEF IN EM METHODS WITH VERY DISTANT SOURCE

An approximate model for the analytical calculation of the terrain relief effect in EM methods with very distant sources (VLF method, afmag method, shallow magnetotelluric sounding) is proposed in this article. The case of two-dimensional forms of relief for E-polarization of a horizontal plane electromagnetic wave is treated. An approximate method of solution is also developed so that the determination of the relief effect can be made even by means of desk calculators. The results of the method introduced when compared with model and practically measured curves show that the proposed model is sufficiently exact for determining the relief effect in EM profiling methods. © 1979.