Dynamic modeling of the propagation of low-frequency seismic acoustic fields in the oceanic medium

Abstract

Numerical modeling of the propagation of wave fields in heterogeneous media has developed signifi� cantly in hydroacoustics, seismic prospecting, and other fields. Since modeling of the physical processes is complicated, a number of simplifications are usually introduced. In particular, the energy losses in the medium are neglected and the approximation of liquid bottom is also applied; however, in this case, shear waves and a number of related phenomena disappear. The other usual simplification is the parabolic approx� imation, which applies a stationary harmonic field source, but in this case the dynamics of the wave prop� agation process is lost, and the waves reflected from the inhomogeneities of the medium and other phe� nomena disappear [1, 2]. In this paper, we perform numerical modeling without the simplifications men� tioned above. The problems of propagation of the pulse seismic acoustic fields over the oceanic waveguides water surface–bottom and at the ocean– continent boundary are considered for the first time in the low frequency range from 0.05 to 1 Hz. Long range propagation of storm microseisms and fields of earth� quakes occur in this range [1–5]. A viscoelastic model of the medium and the generalized Hooke law are applied to take damping into account. The differential equations in partial derivatives of the hyperbolic type are used for the mathematical description. The numerical solution of the differential equations in the problem considered here is performed using the grid models that are closest to the physical conditions of the propagation of fields [6].