Side-scan sonar investigations and hydroacoustic 'bubble' quantification in an area of surface-near gas hydrate occurrences: recent studies from Hydrate Ridge, offshore Oregon

摘要

Cold venting of methane-rich fluids occurs at Hydrate Ridge, an area known for surface-near gas hydrate occurrences. Biogeochemical cycles, the organic and anorganic material turnover rates at vent sites as well as the fate of methane (both dissolved and free gas) were studied during a 2-months cruise using in situ observatories. High-resolution side-scan sonar mapping allows the extrapolation of gas hydrate and massive carbonate occurrences that were visually observed by towed video systems. Ship mounted single beam hydroacoustic systems and a newly designed horizontally looking swath system are used to investigate free gas 'bubbles' that are cyclically released from the seafloor.