A hybrid coupled wave-number integration approach to range-dependent seismoacoustic modeling

Abstract

Recently, a spectral super-element approach was developed for acoustic modeling in fluid waveguides [H. Schmidt, W. Seong, and J. T. Goh, J. Acoust. Soc. Am. 98, 465–472 (1995)]. The approach uses a hybridization of finite elements, boundary integrals, and wave-number integration to solve the Helmholtz equation in a range-dependent ocean environment. It provides accurate, full two-way solutions to the wave equation, using either a full, global multiple scattering solution technique, or an efficient single-scatter, marching solution. This paper extends that work to mixed fluid-elastic stratifications. SAFARI is used as the basic computational engine for generating the Green’s function in an ocean with arbitrary fluid-elastic stratifications. The hybrid model therefore directly provides the spectral decomposition of the wave field in terms of modal components, head waves as well as seismic interface waves. Extensive numerical experiments have shown that the method gives accurate results particularly in the forward scatter direction. For comparisons, we have used a finite element parabolic equation model, a boundary-element code, as well as the recently developed virtual source algorithm.