Dynamic full-wave modeling of storm microseism propagation in an oceanic environment

Abstract

The full-wave modeling of storm seismoacoustic field propagation in oceanic waveguides and at the ocean-continent border in the low-frequency range from 0.01 to 1 Hz using the numerical grid method is considered. The 2D model proposed by Press and Ewing for planar waveguides above the homogeneous elastic halfspace was chosen as a basis. The influence of a layer of deposits and features of the crust of the oceanic- and continent-type was taken into account in the more complex model. The effects of the carrier frequency, orientation of directivity diagram of the signal source, and steepness of the continental slope were investigated. A system of the second-order linear partial differential equations of hyperbolic type was solved in the process of modeling. The inertia properties and attenuation in the medium were taken into consideration. Fast-operating locally recursive nonlocally asynchronous parallel algorithms were used in the modeling, which were developed at the Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences for modeling of plasma processes. At present, these algorithms are adapted for modeling of geophysical fields. A computing system consisting of two computers based on eight-core processors is used for computations. As a result, instantaneous pictures of microseism field propagation were constructed at the specified cross sections of the medium at sequential time moments, and the microseism’s frequency spectra and synthetic seismograms were obtained for some characteristic points of aqueous medium, bottom sediment, and land. The considered algorithms of full-wave numerical modeling and the computing system can be easily adapted to the 3D variant of anisotropic and inhomogeneous media specified by analytical expressions.