P-wave velocity models of continental shelf of East Siberian Sea using the Laplace-domain full waveform inversion

• Main Authors: Kang, Seung-Goo, Hong, Jong Kuk, Jin, Young Keun, Jang, Ugeun, Niessen, Frank, Baranov, Boris
• Format: Conference Object
• Language: unknown
• Published: American Geophysical Union 2017
• Subjects: Arctic; Arctic Ocean; East Siberian Sea; Laplace; Alfred Wegener Institute; Beaufort Sea; Korea Polar Research Institute; permafrost
• Online Access: https://epic.awi.de/id/eprint/49563/; http://adsabs.harvard.edu/abs/2017AGUFM.T13B0522K; https://hdl.handle.net/10013/epic.2c9774a8-b39c-487f-8aef-04b17a07e431

2016 IBRV ARAON Arctic Cruise Leg-2, Expedition ARA07C was a multidisciplinary undertaking carried out in the East Siberian Sea (ESS) from August 25 to September 10, 2016. The program was conducted as a collaboration between the Korea Polar Research Institute (KOPRI), P.P. Shirshov Institute of Oceanology (IORAS), and Alfred Wegener Institute (AWI). During this expedition, the multi-channel seismic (MCS) data were acquired on the continental shelf and the upper slope of the ESS, totaling 3 lines with 660 line-kilometers. The continental shelf of ESS is one of the widest shelf seas in the world and it is believed to cover the largest area of sub-sea permafrost in the Arctic. According to the present knowledge of the glacial history of the western Arctic Ocean, it is likely that during the LGM with a sea level approximately 120 m below present, the entire shelf area of the ESS was exposed to very cold air temperatures so that thick permafrost should have formed. Indeed, in water depths shallower than 80 m, sub-bottom profiles in the ESS recorded from the shelf edge to a latitude of 74°30' N in 60 m water depth exhibited acoustic facies, suggesting that at least relicts of submarine permafrost are present. In order to identify the existence and/or non-existence of subsea permafrost in our study area, we analyze the MCS data using the Laplace domain full waveform inversion (FWI). In case of the Canadian continental shelf of the Beaufort Sea, subsea permafrost has high seismic velocity values (over 2.6 km/sec) and strong refraction events were found in the MCS shotgathers. However, in the EES our proposed P-wave velocity models derived from FWI have neither found high velocity structures (over 2.6 km/sec) nor indicate strong refraction events by subsea permafrost. Instead, in 300 m depth below sea floor higher P-wave velocity structures (1.8 2.2 km/s) than normal subsea sediment layers were found, which are interpreted as cemented strata by glaciation activities.