Seismic wave attenuation in rock due to friction

The total attenuation in rock is probably due to a number of sources of dissipation. The mechanism proposed here as one source of attenuation is based on the frictional dissipation as crack surfaces in contact slide relative to one another during passage of a seismic wave. The attenuation due to friction at cracks is derived for dilatation and shear waves under the assumption that the cracks may be approximated as elliptical slits in plane strain. The results cannot be evaluated on an absolute basis; however, the ratio Qα/Qβ of the quality factor for longitudinal waves to that for transverse waves predicted by the theory agrees reasonably well with published values (all of which equal approximately 0.5) found in laboratory experiments on granite and limestone.