Traditionally, compaction has been determined from seismic stacking velocities or sonic logs. The use of stacking velocities requires a considerable human effort, since consistent velocity picks must be obtained. We propose to fit a depth dependant velocity function to seismic travel time information using the semblance criterion, and thereby obtain estimates of important parameters describing lithology and compaction. The need for human interaction is thus reduced, and more reliable estimates are obtained. Furthermore, the method uses all available travel time information in the depth interval to be analyzed, including zones of weak reflections.