Pre-earthquake Magnetic Pulses

TL;DR

This paper models pre-earthquake magnetic pulses using a semiconductor approach, explaining their origin as transient currents in rocks that can be used to locate stress buildup zones before earthquakes.

Contribution

It introduces a coupled semiconductor and magnetic field model to explain unipolar magnetic pulses observed prior to earthquakes, linking electrical currents in rocks to electromagnetic signals.

Findings

Model reproduces observed pulse characteristics

Rocks can act as diodes producing transient currents

Magnetic pulses can be triangulated to stress zones

Abstract

A semiconductor model of rocks is shown to describe unipolar magnetic pulses, a phenomenon that has been observed prior to earthquakes. These pulses are observable because their extremely long wavelength allows them to pass through the Earth's crust. Interestingly, the source of these pulses may be triangulated to pinpoint locations where stress is building deep within the crust. We couple a semiconductor drift-diffusion model to a magnetic field in order to describe the electromagnetic effects associated with electrical currents flowing within rocks. The resulting system of equations is solved numerically and it is seen that a volume of rock may act as a diode that produces transient currents when it switches bias. These unidirectional currents are expected to produce transient unipolar magnetic pulses similar in form, amplitude, and duration to those observed before earthquakes, and this suggests that the pulses could be the result of geophysical semiconductor processes.