Lack of adequate velocity data can sometimes be overcome by the proper co-ordination of seismic and geologic factors. The basic assumption that seismic and geologic data are directly correlatable must be utilized to its fullest extent. Upon this basis reliable basic seismic data of time and delta t values are computed with variations in the other parameters to make the computed seismic data closely match the known geologic conditions by one of several standard computing methods. The empirical fitting of the seismic data to match geologic conditions establishes the velocity gradient which can be then be extrapolated into immediately adjacent areas. An iso-velocity section can also be prepared, if desired. Generally, it appears that iso-velocity contours parallel formational strikes. The application of such empirically derived velocity data will result in seismic structural maps and cross-sections which are compatible with actual geologic conditions. The value of the oftentimes neglected true dip section is shown and is actually an integral part of the analysis. The application of electronic computing techniques makes such determinations much more rapid and makes the method entirely feasible.