CONCLUSIONS

I have presented a method that greatly simplifies traveltime calculations on a regular grid. The algorithm has the advantage over Vidale's method that all points can be treated equally, i.e., no minimum traveltime points have to be found at each extrapolation step, and no choices based on local wavefront curvature have to be made. The computations are vectorizable, and allow efficient calculation of Greens's functions in Kirchhoff methods.