Seismoelectric conversions due to a ground source in stratified porous media

The penetration and diffusion of fluids in fluid-saturated porous media can cause electromagnetic (EM) disturbances due to the electrokinetic effect. These mechanically induced EM waves, often known as the seismoelectric wave fields are sensitive to hydraulic parameters such as porosity and permeability. For in-situ seismoelectric field observations, the source and receivers are usually located at or near the ground surface. However, the current reflectivity-method-based seismoelectric modeling algorithms will suffer computational difficulties due to the slow convergence problem occurring when the source and receiver are located at close or the same depths. To overcome this problem, we extend the peak-trough averaging method to update the seismoelectric modeling algorithm based on the Luco-Apsel-Chen generalized reflection and transmission method. The updated seismoelectric algorithm is then applied to study the seismoelectric coupling phenomena. The results demonstrate that the electric signals recorded by a surface receiver are several milliseconds earlier than their causative seismic waves due to the evanescent seismoelectric conversion. This is capable to interpret similar phenomena reported in seismoelectric field observations over a long history. This time difference may have the potential to identify the location of the groundwater table. Therefore, the updated seismoelectric algorithm is a precise and efficient tool for forward modeling, which also benefits the interpretations of field seismoelectric observations.