Propagation of seismic-induced electromagnetic waves in a semi-infinite porous medium: A Fourier transform approach
R. Arief Budiman, Aqsha Aqsha, Mehran Gharibi, Robert R. Stewart
Numerical simulations of seismic-induced electromagnetic waves in a semi-infinite, saturated porous soil were carried out using COMSOL Multiphysics software. The governing equations used are Maxwell's equations and wave (Navier) equations for the elastic displacements in the solid and fluid phases, and linear constitutive equations. The coupling between seismic and electromagnetic waves defines the seismoelectric effect. The simulations were performed in frequency domain over the range of 0-64 Hz. Fast Fourier transform with a frequency range of 1-32 Hz gave us the time-dependent soil responses. The spectra of energy absorption in the solid and liquid phases produce two identical peaks at 25 and 48 Hz. We attribute these peaks to a resonance effect with a slight dissipation from viscous drag force. The electric field produced was dominated by conduction and we did not observe any large-scale dipole formations. The induced magnetic field on the surface is around 1-10 nT from an excitation surface force peaking at 10 MN.