The time-reversal of different kinds of waves, e.g. electromagnetic, sound, to optimize focusing has been studied in both homogeneous and inhomogeneous media. This thesis aims to further develop the time-reversal technique to include seismic waves. In order to apply the concept of the time-reversal cavity we simulate the seismic waves originating from a point source in a simple cubic volume using SeisSol. We then use the recorded signals at the surface to produce a time-reversed wave. As a proof of concept this is first developed in a simple homogeneous, acoustic medium, and later expanded to include inhomogeneous, elastic media. In both cases the time-reversed wave indeed corresponds to the outgoing wave. Even with a small number of receivers at the surface can the origin of the point source be estimated.