f Seismic properties of marine sediments

Physical parameters of marine sediments are important data for the identification of sediment types as well as for the estimation of geotechnical data for offshore engineering purposes . They are more easily accessible than sedimentological propertjes especially under in situ cónditions . Seismic methods are mainly prefered for structural investigations of the seafloor . On the other hand, these data contain also information on the complex dynamic moduli of compressional and shear waves in the sediments . Shear waves are important for the investigation of physical parameters as their velocities cover a large range of values between 10 and 300 m/sec, whereas compressional wave velocities are in a limited range between about 1450 and 2000 m/sec in near surface layers of the sea floor . Shear waves are not influenced by the pore fluid or the degree of saturation, the velocity depends only on grain structure. Compressional wave velocities, on the other hand, depend strongly on the kind of pore fluid and especially on the degree of saturation .