Modeling of electromagnetic fields generated by an earthquake due to piezomagnetic effect

In this research, we explore the EM response generated by earthquake fault-slip attributable to the piezomagnetic effect. To achieve this, we integrate the elastodynamic equations with Maxwell's equations. We put forward a semi-analytical method for simulating seismo-electromagnetic fields within a horizontally-stratified model. In this model, the coupled equations are resolved in the frequency-wavenumber domain. Subsequently, the seismo-electromagnetic responses in the time-space domain are obtained through the Hankel transform and the inverse Fourier transform. We carry out numerical simulations to examine the characteristics of the EM signals triggered by a fault - slip source. The results indicate that the piezomagnetic effect can generate both magnetic and electric fields. For an Mw 6.0 earthquake, at a receiver 85 km from the epicenter, the coseismic electric field can reach approximately ~0.1 μV/m, and the coseismic magnetic field can reach about 0.1 nT. This demonstrates that the EM fields resulting from the piezomagnetic effect are detectable by current EM equipment. Furthermore, we apply this method to simulate the observed coseismic EM data from an actual earthquake. The predicted magnetic fields show a high degree of consistency with the data, validating the effectiveness of our method.