f Elastic iterative migration of offset VSP data

Linearized elastic migration/inversion has previously been applied to real offset VSP data by Beydoun et al. (1990). Their scheme was based on the least-squares approach to inversion and a ray-Born approximation (Beydoun and Mendes, 1989). In this paper, a non-linear iterative elastic migration/inversion scheme (Mittet et al., 1992) is tested on synthetic offset VSP data. The scheme is based on two sets of measured boundary conditions (displacement velocity and traction) in the misfit function. The implementation of the wave propagation is based on a high-order finite difference technique (Mittet et al. (1988)).