ASA 126th Meeting Denver 1993 October 4-8

2pUW8. Two-dimensional modeling of low-angle backscatter from geologically realistic seafloors.

R. A. Stephen S. A. Swift

Dept. of Geol. and Geophys., Woods Hole Oceanogr. Inst., Woods Hole, MA 02543

The numerical scattering chamber has been used to quantitatively predict low-angle backscatter coefficients for a suite of seafloor models. A number of issues have been addressed: (a) How finely does seafloor bathymetry need to be resolved in order to predict the backscattered field? Corollary issues in this area are (i) at what resolution can one go from a deterministic to a stochastic representation and (ii) how should one interpolate between bathymetric data points? (b) How important are shear (rigidity) properties of the sediment and basement in a predictive model of seafloor backscatter? (c) How important is intrinsic attenuation (anelasticity) in a predictive model of seafloor backscatter? (d) How do the magnitude and mechanisms of backscatter vary with increasing sediment cover? (e) How effective are isolated facets on the seafloor in generating strong backscatter? (f) Can realistic volume heterogeneities within the sediment and basement generate comparable backscatter levels to realistic seafloor roughness? These issues will be discussed by comparing backscatter coefficients for various seafloor representations.