Fate of methane gas bubbles emitted from the seafloor along the Western Atlantic Margin as observed by active sonar Free

A method for characterizing and quantifying marine methane gas seeps along the Western Atlantic Margin (U.S. East Coast) was developed and applied to 70 free-gas seeps observed by the R/V Okeanos Explorer in 2012 and 2013, in water depths ranging from 300–2000 m. Acoustic backscatter from an 18 kHz split-beam echo sounder and a 30 kHz multi-beam echo sounder provided information on the height to which the gas seeps rose from the seabed. Profiles of the depth-dependent target strength and scattering strength per unit depth were generated from the acoustic data. These profiles were compared to models of the evolution of rising bubbles in order to help constrain the ultimate fate of the bubbles. Of particular interest are comparisons of profiles for seeps originating below, at, and above the gas hydrate stability zone.