ELECTROMAGNETIC FIELD IN A NONUNIFORM SPHERE (3D case)
V.V. Plotkin
Institute of Geophysics, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
Keywords: Electric and magnetic modes, deep electromagnetic soundings, induction and galvanic sources, impedance, inhomogeneous medium, electrical conductivity
Pages: 1107-1119
Subsection: GEOPHYSICS
Abstract
The paper presents a new approach to the problem of global electromagnetic field simulated as a nonuniform sphere excited by external induction or galvanic source currents. The forward problem with arbitrary nonuniform sources is solved taking into account the dependence of electrical conductivity on both radial and angular coordinates. The angular and radial dependences and amplitude variations of electric and magnetic fields are computed assuming that deviations from spherical symmetry are caused by mid-mantle or surface conductivity perturbations associated with induction and galvanic excitation. The inverse problem is solved using a mode approach.
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