Grid data for topography and backscatter maps of massive gas hydrate recovery area between the Umitaka Spur and the Ogi Spur in the Sea of Japan
Massive gas hydrates of biogenic methane were recovered from mound structures at ~20 km northeast to the Umitaka Spur in the Sea of Japan. Mound structures at the Umitaka Spur are associated with thermogenic methane. This is owing to influence of hydrocarbon source rocks at deep sediment depths. These source rocks are widely distributed for the oil and gas fields along the eastern margin of the Sea of Japan. Therefore, the local occurrence of intensive biogenic methane production suggests unique trigger in deep. Investigation of this area and comparison with the Umitaka spur will be useful for understanding complicated nature in deep sediment depths. Geophysical data for topography and backscatter maps were obtained during the 1K17 cruise (July 2017) and the 2K19 cruise (July 2019) by R/V Kaiyo Maru No.1 and R/V Kaiyo Maru No.2 of the Kaiyo Engineering Co., Ltd. (http://kaiyoeng.com/eng/), respectively. Data for the southern part of the focused area was obtained during the 1K17 cruise and northern part, during the 2K19 cruise. The equipment attached to the ship bottom was used (EM122 and EM304 of Kongsberg during the 1K17 cruise and the 2K19 cruise, respectively). Raw data of the equipment was processed using a software, MarineDiscovery, of Ocean High Technology Institute, Inc. (https://www.ohti.co.jp/www/en/products/software/marinediscovery/) and converted into ~25 m mesh (0.8 second) grid data for both topographic map and backscatter. Grid data covering both areas was prepared only for topography map due to difficulty in calibration for sound intensity. Uploaded data Topography map of northern area (Topography map of northern area.pdf) Topography map of southern area (Topography map of southern area.pdf) Grid data for topography at northern area (2K19_Joetsu_LM_DP.grd) Grid data for topography at southern area (1K17_Izumozaki_DP.grd) Grid data for topography_marged (1K17_2K19_Joetsu_LM_DP.grd) Grid data for backscatter at northern area (2K19_Joetsu_LM_BS.grd) Grid data for backscatter at southern area (1K17_Izumozaki_BS.grd)
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Grid data for the Generic Mapping Tools (GMT).