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-P04] Tsunami deposits recorded around the Lake Jusanko, Tsugaru Peninsula

*Rina Okada1, Takanobu Kamataki2, Koji Umeda1 (1.Hirosaki University, 2.Akita University)

Keywords:tsunami deposits, 1741 Oshima-Oki tsunami

Tsunami deposits are interpreted to be formed by traction processes associated with tsunami and are particularly used for marine deposits formed during the “backwash” phase. Such deposits are being used to identify past tsunami events and thereby better constrain estimates of both earthquake and tsunami hazard. 12core samples, taken using the handy geoslicers, collected on coastal land revealed candidates of historic and prehistoric tsunami sands around the Lake Jusanko in the Tsugaru Peninsula, northeast Japan. The deposits mainly consist of massive (sometime laminated), graded sands, peats and muds Two of sand layers at depths of 100-130 cm were regarded as tsunami deposits judging from sedimentary structures, mineral assemblages of sands and grain-size distribution curves. Radiocarbon dating of plant fragments just beneath the tsunami deposits provides an age close to the AD 1741 Oshima-Oki tsunami, which is considered to be due to the submarine debris avalanche of the Oshima-Oshima volcano.