Modeling seismic waves in ocean with the presence of irregular seabed and rough sea surface

Abstract

Abstract For the simulation of seismic wavefields in the ocean, it is very important to consider the influences of the irregular seabed and the rough sea surface. To numerically model seismic waves in the ocean, the fluid seawater and the solid seabed must be treated separately, and the air–fluid and fluid–solid boundary conditions must be considered simultaneously. A fluid–solid configuration is created with the influences of a rough sea surface and an irregular seabed to carry out wavefield simulation. Based on the boundary conformal grids, the 2D acoustic wave equations (in the fluid media), the 2D elastic wave equations (in the solid media) and two boundary conditions (at the interface between air and fluid and the interface between fluid and solid) are converted from the Cartesian coordinate system into a curvilinear coordinate system. In curvilinear coordinates, the seismic wave equations and boundary conditions are discretized with finite-difference operators. At the left, right and bottom boundaries of the model, the convolutional perfectly matched layer boundary condition is used to absorb artificial reflections. The numerical simulation results show that the snapshots and shot gathers of the rough sea surface model are more complex and contain stronger reflections than those of the flat model. The rough sea surface and the pattern of the irregular seabed have a great influence on the propagation of seismic waves in the ocean.