Comparison of the Rayleigh wave in elastic and viscoelastic media

Dispersion properties of Rayleigh-type surface waves can be used for imaging and characterizing the shallow subsurface. This paper models Rayleigh waves in complex viscoelastic media by using the time-domain finite difference method on the rotated staggered grid. We compared the dispersion properties of the viscoelastic Rayleigh wave with the elastic one. We proposed a method to model the Rayleigh wave based on the second-order displacement-stress viscoastic wave equations and the unspilt convoutiona perfecly matched hyer absorbing boundary condition. The validity of our method is tested by two examples. Then, the wave fields are calculated in a laterally heterogeneous media and a media with cavity. We analyzed the dispersion properties of the Ray'eigh waves. The dispersion curve varies consideraNy with quabty factor Q in shallow subsurface; the higher modes of Rayleigh waves are generated and possess significant amounts of energy for strong attenuation.