CONCLUSIONS

The synthetic modeling results confirm the point that near surface velocity variations create not only timing anomalies, but also focusing anomalies. These focusing anomalies cannot be compensated for by static shift. Near surface variations cause distinct trajectories in midpoint-offset plots of trace power. Preliminary results show that slant stack imaging based on these power plots can be used to locate velocity perturbations. Once these perturbations are located, the seismic wavefield can be extrapolated through the near surface to iteratively estimate velocity. Much work remains to be done in order to implement and link these two steps, but the results presented here are encouraging.