An efficient implementation of the free surface boundary condition in 2-D and 3-D elastic cases

Interpretation and inversion of seismograms recorded at the Earth's surface require precise methods to model seismic waves. This is particularly important when offsets are large and amplitude-offset information could possibly be used to estimate the elastic properties of the subsurface. The finite-difference approach is capable of modeling waves in complex heterogeneous media although it is difficult to assure a precise solution near the free surface which may lead to inaccurate source and receiver directiv-ities and numerically dispersive Rayleigh waves. We use a cost effective implementation of the free surface boundary condition which permits the use of staggered grids without significantly increasing the number of grid points in order to ensure sufficient convergence of the numerical solution to the physical solution.