Acquisition and inversion of dispersive seismic waves in shallow marine environments
Dispersive Scholte waves as well as acoustic guided waves have been excited by surface towed airguns and recorded with stationary receivers (OBS) and a towed hydrophone array. The inversion of the recorded wavefield spectra was adapted to the data from shallow marine environments. The dispersive interface wave travelling along the sea floor (Scholte Wave) is sensitive to the shear wave velocity (Vs) of the sediment and could be sucessfully recorded and inverted at different sites in Kiel Bay and the south-east rim of the Arkona Basin in the Baltic Sea. Limitations remain for very soft sediments with Vs < 50m/s. The acoustic guided wave is sensitive to density and compressional velocity (Vp) as well as Vs. Shear wave velocity and high resolution Vp information could be obtained from the inversion of this wave type in the central Arkona Basin, where very soft sediments (10-20m) overlaid the till and chalk layers, and no interface wave was observed. The lateral variation of the dispersion of Scholte waves was observed with the towed acquisition system, which could be suitable to effciently locate areas with a high shear wave velocity basement at shallow (0-100m) depth.