Magnetotelluric Sounding on a Layered Earth With Transitional Boundary*

This work deals with a theoretical investigation of the magnetotelluric sounding where the horizontal layers of a geological section do not have a sharp but a transitional boundary. The ratio of the horizontal electric to the horizontal magnetic components gives a measure of “Cagniard impedance”, which together with the phase relationship between them, enables one to determine the subsurface geometry and the true resistivities. Utilising the principle of similitude a set of Resistivity Master Curves and the corresponding phase relationships are presented here for the case where the lower half‐space is infinitely resistive. The relation between the relative transition thickness and the cut‐off period is illustrated.