Low shear asymptotics for elastic seabeds

This paper deals with the low sheer asymptotics of the sound field propagat ing in a fluid layer with a homogeneous elastic seabed. Using the displacem ent formulation and applying WKB, we show that although the problem is form ally a singular perturbation problem, it can be reduced to a regular one, a nd we construct a regular expansion for the elastodynamic held in the botto m. The same results come out using alternative formulations, based either o n Lame potentials or on the Love function. The later formulation appears to have independent interest, as it explains why the problem under investigat ion does not fall in the existing framework of coercive singular perturbati ons which appear in one-dimensional elasticity. (C) 2001 Elsevier Science L td. All rights reserved.