Variability of Shear Wave Speed and Attenuation In Surficial Marine Sediments

Abstract

Values of shear wave speed and attenuation in surficial marine sediments (upper 30 cm) are summarized and then correlated with easily measured sediment physical properties (porosity, bulk density, and mean grain size). Shear wave speed ranges from a low of 5 m/s in soft silty-clays to a high of 150 m/s in hard pack fine sands. Shear wave speed increases with decreasing porosity, increasing bulk density, and increasing mean grain size. Strong gradients in shear wave speed in the upper meter of sediment, related to increased effective stress (overburden pressure) and vertical gradients in sediment properties complicate theses predictive relationships. Shear wave attenuation follows the opposite trends as shear wave speed, increasing with increasing porosity, decreasing mean grain size and decreasing bulk density.