MEASUREMENT OF SEISMO-ACOUSTIC OCEAN-BOTTOM PROPERTIES IN THE HIGH ARCTIC

This paper describes a high-resolution seismic experiment designed to measure compressional and shear properties of the ocean bottom in the Lincoln Sea, north of Ellesmere Island, Canada. A three-component ocean-bottom seismometer (OBS) was deployed through 4 m of multiyear sea ice in 540 m of water, and used to record broadband signals from explosive sources detonated on the seafloor at ranges from 35 to 900 m. Subsequently, a layered compressional-speed model was determined from a travel-time analysis of refracted compressional waves, and a shear-speed model was determined by matching the observed dispersion characteristics of Scholte and shear waves using the full-wave numerical propagation model SAFARI. Compressional and shear attenuation coefficients were estimated from an analysis of the decay of signal amplitude with range; an approximately linear increase in attenuation with frequency was observed for both wave types. The sensitivity of acoustic propagation in the ocean to the various geoacoustic parameters was investigated using the propagation model.