Geophysical Journal | 2003 volume 25 1

Theoretical principles of geoelectromagnetic soundings with considering sphericity of field sources

© Shuman V.N.

Physic-mathematical principles of geoelectromagnetic sounding systems are discussed with considering the sphericity of magnetotelluric field sources that combine possibility of electromagnetic field generation with poloidal and toroidal properties. Some aspects of electrodynamics of spherical sources associated with the effect of dynamo-excitation are specified. Informational characteristics of the radial (vertical) electrical field component belonging to the "galvanic" mode and which consists of two parts - potentional (electrostatic) and inductional are studied. Physical mechanisms of the effect of endogenous factors on the surface charges redistribution that characterize the electrostatic part of this field component are analyzed.
A general theory of impedance measurements in geoelectromagnetic methods based on the input of two scalar parameters of impedance type is developed that does not demand apriori information on the inducing field structure. The idea of the generalyty of the magnetotelluric and magnetovatiational methods of geoelectrics based on the generalized impedance equation is realized. Application of this theory to processing and interpreting the results of a magnetotelluric experiment, its unification, further methodical orientation and search for a new trend of the method development are show.

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