Dry versus saturated measurements indicate that both shear and bulk moduli increase upon saturation in all rocks except for the limestone. The increase is greatest for the bulk moduli and the greatest at lower confining pressures for both bulk and shear moduli. For the higher porosity sandstones the saturated S-wave velocities are higher than dry at low pressures and cross over at the higher pressures as the effect of density supersedes the effect of saturation on the shear modulus. Velocity data are compared with various models. The Gassmann equation for saturated effective bulk modulus does not predict saturated P-wave velocities for either low porosity granitic rocks or higher porosity sedimentary rocks.
Predicted velocities are consistently low even if the shear modulus is used.
Using the fluid density to predict saturated S-wave velocities cannot account for the higher shear moduli. Although the velocity data can be interpreted on the basis of these crack models it is not the purpose here to judge whether or not they are appropriate for all rocks, only to note the consistency between observations and these models as constructed.