Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Evening Poster

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS11] tsunami deposit

Tue. May 22, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Tetsuya Shinozaki(Center for Research in Isotopes and Environmental Dynamics (CRiED), University of Tsukuba), Takashi Chiba(Maritime Disaster Prevention Center), Daisuke Ishimura(首都大学東京大学院都市環境科学研究科地理学教室)

[MIS11-P05] Sediment environment change from diatom analysis in Hirota Bay

*Kosuke Tsutsumi1,2, Izumi Sakamoto1, Yuka Yokoyama1, Rihoko Saito1,3, Naoki Haramishi1,4 (1.Tokai University, 2.IEDA Consultants, Inc., 3.Arc Geo Support Co., Ltd, 4.FUKADA SALVAGE & MARINE WORKS CO., LTD)

Keywords:Diatom, Tsunami

The Tohoku great earthquake disaster that occurred on March 11, 2011 gave tsunami damage to the wide range of the Tohoku district. In this study,we aimed for clarifying the sedimentation environment change after the tsunami in the Hirota bay. We performed sound wave exploration, particle size analysis, diatom analysis in this study. As the result, next 1-3 characteristics become clear. 1)Sabulosity sediment is superior in the coastal place, and a particle becomes small off the coast.2)Around Kesen-gawa river, the existence of the coarse sand to gravel zone that formed NW-SE trending was confirmed. 3)Nature of the muddy fine grain sediment is superior in the Karakuwa peninsula side of the gulf west and is sabulosity sediment superiority in the Hirota Peninsula side of the gulf east side. As a result of diatom analysis, freshwater species was dominant in the shore area, and confirmed that the ratio of freshwater species decreased as an offing.