Electrical Conductivity of Fayalite and Spinel

Abstract

A KNOWLEDGE of the electrical conductivity of the Earth at various depths is of importance in many aspects of geomagnetism. It has been suggested¹ that the core of the Earth acts as a self-exciting dynamo, with electromagnetic coupling between the mantle and the core. This coupling depends on the electrical conductivity of the mantle, and some indication of the value of the latter is given by the analysis of the diurnal and secular variations in the geomagnetic field and the sporadic variations arising from magnetic storms. The calculations of Lahiri and Price², which are based on the induction of Earth currents by currents in the ionosphere, indicate that the electrical conductivity of the upper part of the mantle increases considerably with depth.