Shear wave velocity inversion of marine sediments using deep-water OBS Scholte-wave data

Acoustic velocity varies in deep-water environments, and the variable-velocity seawater can affect the dispersion characteristics of Scholte wave. To improve the accuracy of inversion, a horizontal layered-seawater and layered-seabed (HLSLS) model is established with continuously varying velocities for seabed S-wave velocity inversion using Scholte wave. First, we deduced the Scholte wave dispersion equation and the amplitude-depth equation of the HLSLS model based on wave theory. Then, with the real acoustic velocity of the seawater and submarine sediments parameters of the Shenhu area in the South China Sea, we analyzed the influence of variable-velocity seawater on the dispersion characteristics of Scholte wave. Finally, we performed two-dimensional (2D) S-wave velocity inversion on the field OBS multi-component data in the South China Sea. The results showed that the variation of seawater acoustic velocity had a certain influence on the dispersion characteristics of Scholte wave in deep water. The accuracy and practicality of our method were verified through numerical and filed data experiments.