DO TRAVEL-TIMES IN PULSE-TRANSMISSION EXPERIMENTS YIELD ANISOTROPIC GROUP OR PHASE VELOCITIES

The elastic properties of layered rocks are often measured using the pulse through-transmission technique on sets of cylindrical cores cut at angles of 0, 90, and 45 degrees to the layering normal. To discover whether typical experiments of this kind are more likely to measure group velocity, phase velocity, or something in between a laboratory pulse-transmission experiment of Vernik and Nur (1992) is numerically modelled. Most experiments are clearly closer to the phase-velocity case than Vernik and Nur's; it is therefore concluded that almost all pulse-transmission experiments of this kind should measure anisotropic phase velocities, not group velocities. -from Authors