The Overall Conductivity Distribution of the Earth

Abstract

The paper reviews recent work on the problem of determining the distribution of electrical conductivity in the mantle (to depths of about 1000km) from studies of the response of the Earth to externally generated time varying magnetic fields. An attempt has been made to assemble all the available estimates of the response, and to assess their relative reliability. This data can be used to make a preliminary selection of conductivity models, although the refinement of the models is best left to the technique described by PARKER (1971). An initial examination indicates that a model in which the conductivity rises relatively abruptly to about 2mho·m^-1 at a depth of 500 to 600km satisfies the currently available data.