Electrical Coupling Between the Ionosphere and Surface Charges in the Earthquake Fault Zone

Several lithosphere–atmosphere–ionosphere coupling (LAIC) models have been proposed to explain observed precursors before strong earthquakes, such as atmospheric conductivity anomalies and ionospheric total electron content (TEC) variations. These coupling models include (a) radon ionization leading to charged aerosols and change of load resistance in the global atmospheric electric circuit, (b) an electric coupling model of stressed rock–atmosphere–ionosphere based on experimental evidence of stressed rock currents, and (c) ionosphere dynamics with an imposed zonal electric field. Here, we summarize our modeling of stressed-rock–atmosphere– ionosphere coupling for the LAIC process. A physical mechanism of electrical coupling between the atmosphere and surface charge in the fault region is proposed. We also discuss other possible seismic anomalies before and after the earthquake and suggest that in future electric field measurements are used to validate the possible exist-ence of electric activities associated with an earthquake preparation region.