A Resolution Enhancement of Rayleigh Wave Dispersive Imaging using Modified Phase-Shift Method

Abstract

Multi-channel analysis of surface wave (MASW) method is an efficient tool for obtaining vertical shear wave profile. One of the key in the steps in the MASW method is generate a dispersion curves. To generate dispersion energy, the acquired shot gathers data have been transformed from the time-space (t-x) domain to the frequency-phase velocity (f-v) domain using 2D wavefield transformation so that the dispersion curve can be determined by picking the peak of dispersion energy. In this paper, we proposed a modified phase-shift method to increase the resolution of Rayleigh wave dispersive imaging so that the accuracy of the dispersion curve determination becomes higher. This method added processing step on the conventional phase-shift method. The algorithm is written in Matlab environment. We compared this method with the conventional phase-shift and frequency-wavenumber (F-K) method and applied to synthetic and real data. We used DISECA program in Matlab to generate synthetic waveforms. Our results from the synthetic and real data show that modified phase-shift method can improve the dispersion energy imaging resolution better than the conventional phase-shift and F-K method.