The frequency of electromagnetic waves generated by microcracks and its seismic significance

Electromagnetic precursor anomalies are an important indicator for earthquake prediction, with numerous observations, simulations, and theoretical studies available. However, the generation process of electromagnetic waves, particularly their frequency characteristics, before an earthquake has not been thoroughly studied. This issue is crucial in determining whether the earthquake electromagnetic precursor signal can penetrate the stratum, significantly impacting the theoretical research on earthquake prediction. This paper explores the frequency of electromagnetic waves generated in the seismogenic zone before an earthquake through elastic mechanics and microcracks. Simulation results indicate that the lowest frequency of electromagnetic waves is 1341 Hz, sufficient for propagation from the seismic source zone to the surface. The simulated abnormal current near the seismic source zone is about 106 A, consistent with observations. While our work is just a starting point, this study offers theoretical support for the generation and propagation of earthquake electromagnetic precursor signals.