Surface wave analysis of marine seismic data - Scholte wave simulation

The study of geophysical properties of shallow marine environments is critical for characterising the subsurface in offshore sites for both the oil and gas industry and also the geotechnical characterisation of the soil for the construction of sites like the ones for off shore wind turbines. Due to the complexity of these environments, like heterogeneity of sediments and complex water-sand interactions, conventional seismic geophysical methods may be challenging, time consuming and costly. This thesis focuses on the importance of studying Scholte waves propagation along the seabed in order to successfully characterise shallow marine sediments and further improve the resolution of subsurface models in coastal environments. This study is achieved through the creation of multi-layer 3D models with known density, P-wave velocity and S-wave velocity values from which the synthetic seismogram traces are produced using a Finite Difference Algorithm (FDA) provided by the SOFI3D software. The dispersion curves of the Scholte wave velocities are extracted and isolated at low frequencies to reveal a relationship between frequency and velocity. Through the process of inversion, the S-wave velocity versus depth profile is derived providing an insight into the subsurface volume and subsequently recognising any lateral variations and layering characteristics