Surface wave dispersion beyond cutoff for a fast layer on a slow substrate

The velocity and attenuation of pseudosurface waves beyond cutoff have been calculated for several layers on a slow substrate and unexpectedly different kinds of behavior can be distinguished. When the elastic properties of the layer and the substrate are not very different, the velocity of the pseudosurface wave beyond cutoff increases up to the Rayleigh wave velocity of the layer. When the elastic properties of the two materials are quite dissimilar, the pseudosurface wave tends towards an attenuated interfacial mode. In addition, another mode appears evolving into the Rayleigh wave of the layer material.