Electroseismic Scholte-wave analysis: A potential method for estimating shear-wave velocity structure of shallow-water seabed sediments

The potential application of conducting Scholte-wave analysis using electroseismic pressure fields excited by an electric current source due to the electrokinetic effect in fluid-saturated porous seabed sediments is investigated. First, we develop a numerical modelling algorithm by combining the Luco-Apsel-Chen generalized reflection and transmission method with the peak-trough averaging method to simulate the electroseismic wave fields in stratified fluid/porous media. The modelling results show that the electroseismic pressure signals recorded on the seafloor are mainly composed of evanescent electroseismic waves, and Scholte waves are the dominant wave pattern. Their amplitudes are generally within the order of magnitudes capable of being detected by current seismic instruments. Then, the modified frequency-Bessel transform method is extended to extract the Scholte-wave dispersion curves from electroseismic pressure fields. Results demonstrate that Scholte-wave dispersion curves extracted from electroseismic records are superior to those extracted from conventional seismic wave fields excited by an airgun source under the same source-receiver geometry because they contain many overtones and are almost free from the interferences of dispersive guided waves. Furthermore, the Scholte-wave dispersion inversion results obtained by employing the Levenberg-Marquardt method show that the shear-wave velocity model inverted by Scholte-wave dispersion curves extracted from the electroseismic pressure field is more accurate than those obtained by dispersion curves extracted from the seismic wave fields with the guided-wave removal. The above results indicate that the electroseismic Scholte-wave analysis method has the potential to evaluate the shear-wave velocities of shallow-water seabed sediments.