We study the isotropic elastic wave equation in a bounded domain with boundary
with coefficients having jumps at a nested set of interfaces satisfying the
natural transmission conditions there. We analyze in detail the microlocal
behavior of such solutions like reflection, transmission and mode conversion of
S and P waves, evanescent modes, and Rayleigh and Stoneley waves. In
particular, we recover Knott’s equations in this setting. We show that knowledge
of the Dirichlet-to-Neumann map determines uniquely the speed of the P
and the S waves if there is a strictly convex foliation with respect to them,
under an additional condition of lack of full internal reflection of some of the
waves.
Keywords
elasticity, microlocal, inverse problem, transmission
problem