A Multi-Frequency Look at Gas Seeps on the East Siberian Margin

TitleA Multi-Frequency Look at Gas Seeps on the East Siberian Margin
Publication TypePoster - Conference
AuthorsWeidner, E, Mayer, LA, Weber, TC, Jakobsson, M, Chernykh, D, Ananiev, R, Mohammad, R, Semiltov, I
Conference NameAGU Fall 2015 Conference
Conference DatesDecember 14-18
PublisherAmerican Geophysical Union
Conference LocationSan Francisco, CA
Keywordseast siberian margin, gas seeps

The Swedish-Russian-US Arctic Ocean Investigation of Climate-Cryosphere-Carbon Interactions (SWERUS-C3)is a multi-investigator, multi-disciplinary program aimed at increasing our understanding of the climate-cryosphere-carbon system of the Eastern Siberian Arctic Ocean.In 2014, SWERUS-C3 carried out a two-leg field program on the Swedish Icebreaker ODEN. A component of the SWERUS-C3 program focused on water column mapping of the spatial distribution and geologic context of gas seeps using the acoustic systems on board ODEN(12kHzEM122 multibeam echosounder, 2-8kHzSBP120 subbottom profiler, and an 18kHzEK60split-beamsonar). On Leg 2 of the 2014 expedition, a new wide-band transceiver (EK80) was added to the split-beam echosounder and calibrated, providing the ability to measure the acoustic response of the gas seeps over a much broader range of frequencies (15-30kHz). While the broader bandwidth unquestionably provides higher target resolution, a further objective of the broadband mapping was to determine whether information on bubble size distribution could be determined so as to help model the flux of gas coming from the seeps. On Leg2, 53seeps were identified in the vicinity of Herald Canyon.The wide-swath, high-resolution multibeam bathymetry (from the EM122) and high-resolution chirp subbottom profiling (from the SBP120 multibeam subbottom profiler), combined with water column imaging of seeps collected at both 12kHz (from the EM122) and 15-30kHz (from the EK80) offer an important opportunity to understand the spatial distribution of seeps and their relationship to local and regional processes as determined from seafloor and subsurface structure, as well as to explore the potential of extracting quantitative information about the magnitude of gas transportfrom the seeps.