Multimode wave-equation-based Scholte wave inversion

Abstract

Scholte waves are interface waves propagating along fluid-solid boundaries, such as the sea bottom. They are often recorded by ocean bottom nodes (OBN)/cables (OBC) and regarded as noise in conventional data processing. In this study we present a workflow to estimate a shallow shear wave velocity model below the sea bottom by inverting Scholte waves, and demonstrate it on an OBN dataset from North Sea. We use a spectral element (SEM) seismic propagator to simulate the propagation of the Scholte waves on the irregular bathymetry, and to calculate the model updates. Technically the workflow consists of two components: dispersion curve picking using a machine learning (ML)-based method and dispersion curve inversion. The method is shown to be robust and it is believed to be a good candidate for an early stage of an elastic model building workflow when Scholte waves are observed.