Japan Geoscience Union Meeting 2015

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Poster

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS33] Progress in marine geoscience off Pacific coast of Tohoku after the 2011 earthquake and tsunami

Tue. May 26, 2015 6:15 PM - 7:30 PM Convention Hall (2F)

Convener:*Kazuko Usami(Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology), Ken Ikehara(Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology), Yoshihiro Ito(Disaster Prevention Research Institute, Kyoto University), Takashi Toyofuku(Japan Agency for Marine-Earth Science and Technology (JAMSTEC))

6:15 PM - 7:30 PM

[MIS33-P09] Characteristic of palaeoenvironment based on the diatom assembles of the core drilled from Hirota bay, Iwate, Japan

*Tomohito INOUE1, Izumi SAKAMOTO1, Yuka YOKOYAMA1, Masatoshi YAGI1, Satsuki IIJIMA1, Hiroyuki MATSUZAWA1, Tsumoru SAGAYAMA2 (1.Tokai university, 2.Geol.Survey Hokkaido,HRO)

Keywords:diatom, tsunami, deposit

Hirota bay located in Rikuzen takada off the coast is flowed Kesen river from southeastern . The recent 2011Tohoku tsunami strongly affected the coastal area of the Pacific coast of Tohoku. We will show about characteristic of diatom assembles of the columnar core sampled from Hirota bay.
Sakamoto et al(2014) estimated that sandy sediments from 0-71cm is 2011tsunami origin sediments (Unit1) , muddy sediments from 71-143cm is normal sediments in this bay (Unit2) on the 13HV3 core .Results of diatom analysis of the 13HV3 core are that brackish~freshwater species from 0-71cm dominante but brackish-marine species from 75-143cm dominante .
On the 13HV8 core which sampled near the Kesen river , brackish~freshwater species from 0-1cm dominate but brackish-marine species from 42-160cm dominate(Sagayama et al,2014).
Normal sediments on 13HV3 shows marine environment but normal sediments on 13HV8 shows brackish environment. It suggests that the difference of distance from river front and seawater environments (seawater/freshwater ratio) on sampling points.