Bathymetric scattering and seafloor interface waves in long‐range ocean acoustic propagation.

Abstract

Ocean bottom seismometer observations during a long‐range ocean acoustic propagation experiment in the North Pacific in 2004 showed robust, coherent, late arrivals that were not observed on hydrophones suspended 750 m and more above the seafloor and that were not readily explained by ocean acoustic propagation models. These deep seafloor arrivals were the largest amplitude arrivals on the vertical velocity channel for ranges from 500 to 3200 km. They appear to correspond to energy converted from ocean acoustic waves into seafloor interface (Scholte) waves at a small bathymetric high about 18 km from the receivers. Some problems with this model are the following: (a) It is rare to observe discrete Scholte waves propagating 18 km or so on the seafloor. It is usually assumed that Scholte and shear waves decay rapidly in and along the seafloor because of strong scattering and intrinsic attenuation. (b) There is apparently insignificant scattering back into the water column because this would have been observe...