ABSTRACT
Knowledge of seafloor sediment type linked to elastic wave properties is important for understanding underwater sound wave propagation. This is especially true in shallow shelving seas where sound waves interact with the seafloor leading to mode conversions from compressional to shear waves. The velocity and attenuation of horizontally polarised surface shear waves (SH-waves, or Love waves) were measured in situ at eight seafloor sites in the Strait of Hormuz during research cruise CD104 (21 March–19 April 1997) in water depths 75–93 m using a seabed lander called SAPPA. The Hormuz measurements were subsequently calibrated using the same seismic source and receiver on a wet quartz beach sand in the UK; estimated accuracies are 4% for velocity and 0.5 dB/m for the attenuation coefficient. The 200 seafloor samples that were collected showed predominant calcareous (shelly) sands and gravels with significant mud contents over the survey area, with a calcareous mud blanket extending to the north of the main shipping channel. SH-wave velocity and attenuation (1,000/Q, where Q is the quality factor) clustered around values of 15–30 m/s and 25–150, respectively, compared to quartz beach sand values of 96 m/s and 37.
