Wave scattering and diffusion in textured random media
Abstract
Most theoretical investigations of seismic wave scattering rely on the assumption that the underlying medium is statistically isotropic. However, deep seismic soundings of the crust as well as geological observations often reveal the existence of elongated or preferentially oriented scattering structures. In this paper, we develop a radiative transfer theory to describe the propagation and multiple scattering of the acoustic wavefield in an anisotropic random medium. After a few scatterings, the acoustic energy is shown to obey a tensorial diffusion equation. We apply our theory to a simple lithospheric model where a textured and heterogeneous crust overlies a transparent mantle. The deterministic reflection/transmission at the Moho and at the free surface are taken into account rigorously in the boundary conditions of the diffusion equation. In simple geometries, we derive exact expressions of the energy density in the diffusive regime. Our analytical results provide a simple physical interpretation of the well-known Coda Q parameter in terms of the components of the diffusion tensor.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....3347M