Figure 4. P- and S-wave velocity vs. confining pressure measured on Sample 163-990A-10R-1, 12–14 cm (crosses). Also shown are the velocities calculated from the best fitting aspect ratio spectrum determined in the second inversion of the data according to the theory of Kuster-Toksöz (1974) (solid line). The free parameters that were determined in the inversion are the aspect ratio spectrum and the bulk and shear grain moduli. Six different aspect ratios were modeled in this fit to the data. The RMS model misfit for the second inversion is 0.017 km s –1 . The P- and S-wave velocities calculated from the average aspect ratio spectrum from Table 3 are also shown (dashed lines) and have an RMS misfit of only 0.019 km s –1 . Note the similarity between the two model fits (i.e., between the solid and dashed lines). The aspect ratio spectra and RMS misfits for other samples are listed in Table 2.