Interaction mechanism of electric current induced by solar activity and earthquake faults

Solar activity and its sharp variability generally produce large-scale disturbances in Earth’s magnetosphere, inducing geomagnetic fluctuations that can be measured globally through ground-based magnetometers and Low Earth Orbit (LEO) satellite observations. These disturbances, driven primarily by solar wind variability and coronal mass ejections, may cause geomagnetic storms and induce electrical currents in Earth’s ionosphere and crust, leading to measurable electromagnetic signatures. Considering that both tectonic deformation and geomagnetic variations affect the physical state of Earth’s lithosphere (even though with different weights), possible links between solar-driven geomagnetic activity and seismic processes have been proposed in the literature.

Preliminary analyses indicated that while geomagnetic storms produce large and well-defined electromagnetic perturbations in the Earth–ionosphere system and well-recorded by geomagnetic ground magnetometers, any corresponding modulation of seismicity is subtle and difficult to distinguish from background tectonic variability. Nonetheless, localised correlations in highly conductive, fluid-rich fault systems suggest that electromagnetic effects may contribute to earthquake timing in specific geological settings when faults are near the critical failure due to accumulated tectonic stress. Over the past several decades, a number of hypotheses have proposed that such geomagnetic disturbances could influence the timing of earthquake occurrence by modulating crustal stress, pore-fluid pressure, or electrochemical processes along active faults.

This contribution emerged from the International Space Science Institute (ISSI) Team 23-583 (57) meeting activities, which proposed a new hypothesis of geomagnetic–seismic coupling where geomagnetic fluctuations generate electric currents within the conductive layers of the lithosphere. The hypothesis consists of electrolytic deposition of elements on fault surfaces due to telluric currents acting in lithospheric fluids, capable of weakening the cohesion between foot and hanging walls and consequently inducing slippage. Such a hypothesis is compared with others, including (1) Lorentz-force interactions between induced telluric currents and crustal rock masses, (2) electromagnetic triggering of electrokinetic fluid migration in fault zones, and (3) magnetoelastic effects in stressed, magnetically susceptible rocks.

 

Acknowledgment

We acknowledge ISSI (Bern) /ISSI-BJ (Beijing) for supporting the International Team 23-583 (57) “Investigation of the Lithosphere Atmosphere Ionosphere Coupling (LAIC) Mechanism before the Natural Hazards” led by Dedalo Marchetti and Essam Ghamry, and in particular, Prof. Dimitar Ouzounov for fruitful scientific discussions.