SCATTERING BY A RANDOM FIELD OF SURFACE SCATTERERS

A study of elastic wave scattering by a random distribution of surface scatterers has been carried out with a three‐dimensional seismic model. The model consisted of 143 round brass rods cemented to the surface of a large concrete slab. By recording the signals from each detector position with and without scatterers present, we looked at the scattered energy in the absence of the direct signal. We found that (1) the separation for which signals from two detectors ceased to resemble each other (coherence distance) was about 0.3 to 0.4 wavelength of predominant coherent noise, (2) the coherence distance is independent of scatterer size for scatterers with diameters in the range 0.05 to 0.4 wavelength, (3) the amount of scattered energy increases with scatterer size, and (4) all components of motion appear in the scattered energy with about the same average amplitude.