4:30 PM - 4:45 PM
[MIS26-09] Survey of methane hydrate off Hidaka, Pacific Ocean
Keywords:methane hydrate, Submarine topography, marine sediment
In the sea area around Hokkaido, the existence of bottom simulating reflectors (BSR) has been confirmed off Abashiri, Okushiri Island, Hidaka, and Tokachi. In the Pacific Ocean off Hidaka, the National Institute of Advanced Industrial Science and Technology conducted a seismic survey (GH06) in 2006. When the sound wave cross section obtained by GH06 was examined, gas chimneys and mound topography were confirmed at about 10 points on the survey line. Furthermore, in a fishery survey conducted by the research vessel "Kinsei-Maru" of the Hokkaido Research Organization, gas plumes were observed at multiple points on the survey line. Therefore, in order to investigate the distribution of methane hydrate in the Pacific Ocean off Hidaka, we conducted research cruises using the research vessel "Kaiyo-Maru No. 2" of Kaiyo Engineering Co., LTD. and the research training ship "Oshoro-Maru" of the Faculty of Fisheries, Hokkaido University, in 2020 (2K-2020) and 2021 (C114). In the survey, we conducted the seafloor topography and methane plume observation by the multi-beam echosounder and quantitative echo sounder, and the sampling of seafloor sediments using a gravity corer. As a result of the survey, a large number of small-scale diapirs, submarine landslide topography, and gas plumes near the concealed anticlinal axis were observed. In a survey conducted in 2021 (C114), methane hydrate was successfully collected at one site where a gas plume was confirmed. In this report, we report the relationship between the seafloor topography and the soil characteristics of the seafloor sediment, and the relationship between the gas plume points and the seafloor topography, based on the survey results off Hidaka.