FINITE-DIFFERENCE MODELING OF GEOACOUSTIC INTERACTION AT ANELASTIC SEA-FLOORS

A major problem in understanding seismic wave propagation in the seafl oor is to distinguish between the loss of energy due to intrinsic atte nuation and the loss of energy due to scattering from fine scale heter ogeneities and bottom roughness. Energy lost to intrinsic attenuation (heat) disappears entirely from the system. Energy lost to scattering is conserved in the system and can appear in observations as incoheren t noise (reverberation, time spread, angle spread) and/or mode convert ed waves. It has been shown by a number of investigators that the seaf loor scattering problem can be addressed by finite difference solution s to the elastic wave equation in the time domain. However previous st udies have not considered the role of intrinsic attenuation in the sca ttering process. In this paper, a formulation is presented which inclu des the effects of intrinsic attenuation in a two-dimensional finite d ifference formulation of the elastodynamic equations. The code is stab le and yields valid attenuation results.