THE USE OF SEISMIC SHEAR WAVES AND COMPRESSIONAL WAVES FOR LITHOLOGICAL PROBLEMS OF SHALLOW SEDIMENTS*

Abstract

A bstract From a great variety of in situ shear wave experiments, i.e., reflection, refraction and borehole surveys in the shallow sediments of the north German plains, several specific properties have been derived. Shear waves (S) differ from compressional waves (P) in that: they are not affected by the degree of water saturation. Thus, they provide a better correlation between the velocity V s and (solid) lithology; they generally have lower frequencies, but shorter wavelength and, hence, a better resolution of thin layers; they have lower absorption Q s −1 and hence a better penetration in partially saturated and gas‐containing sediments than P‐waves. Correlations have been established between V s and the confining pressure and between reduced V s values and several lithological parameters like the grain size of sandy material. More lithological and hydrological information is obtained by using S‐ and P‐wave surveys along the same profile. The best information on a sedimentological structure is obtained by the simultaneous observation of V s , V p , Q s and Q p .