ASSESSMENT OF TENSOR OF ELECTRICAL-CONDUCTIVITY ANISOTROPY IN THE LOWER MANTLE FROM GEOMAGNETIC DATA
V.V. Plotkin, P.G. Dyad’kov, S.G. Ovchinnikov
Keywords: MagnesiowП‹stite, lower mantle, anisotropy of electrical conductivity, global electromagnetic induction, three-component registration of geomagnetic variations, global network of observatories
Abstract
Anisotropy of electrical conductivity in the lower mantle is regarded as a possible consequence of the phase transition of magnesiowϋstite from semiconductor into metallic state. We propose a method for obtaining information about the tensor of electrical conductivity of a deep anisotropic layer from geomagnetic data of the global network. It is possible to estimate the parameters of the electrical-conductivity tensor which are tangential components of the electromagnetic field by analysis of the characteristics of a magnetic mode. We present the results of processing of real data by the proposed method for the period from 1920 to 2009; the data were borrowed from the Net databank of the monthly values of components X, Y, and Z of the geomagnetic field.
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