Geomagnetic Fields Produced by Electrokinetic Sources

Abstract

Fluid motion in the vicinity of boundary separating regions of different streaming potential coefficients can produce an external magnetic field. We give analytical solutions of magnetic field for horizontally, vertically and diagonally discontinuous earth models and investigate the effect of source geometry. In general, the vertical component of the magnetic field is the largest, and the component parallel to the strike of the source is very sensitive to the dip angle of the source.
We apply our analytical solutions to the magnetic anomalies observed during the swarming Matsushiro earthquakes in 1965 and 1966. MIZUTANI and ISHIDO (1976) proposed an electrokinetic mechanism for the magnetic anomalies observed at Matsushiro, but they did not specify the cause of the electric current flow. We concretely examine the Mizutani and Ishido's hypothesis, using an electrokinetic source in inhomogeneous media. We conclude that it is difficult to explain the observed magnetic anomalies by the electrokinetic coupling.