Effects of irregular topography on Rayleigh-wave propagation in surface-wave exploration

We have conducted finite difference simulation of wave propagation in a 3D shallow soil model with a surface irregularity similar to a river embankment. We found large scattering waves from edges of the surface layer in the synthetic vertical waves at sites on the surface along a surveying line of the crest. The scattering waves do not have significant effects on the dispersive features of Rayleigh waves at the sites close to the source location. However, the effects is large for the sites far from the source, and makes it difficult to apply ID surface wave theory to interpret observed data in the surface-wave exploration.