Japan Geoscience Union Meeting 2015

Presentation information

Oral

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 9:00 AM - 10:45 AM 102B (1F)

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)), Chair:Yoshihiro Ito(Disaster Prevention Research Institute, Kyoto University)

10:15 AM - 10:30 AM

[MIS33-06] Generation process of earthquake-related turbidity currents along the mid slope terrace on the Japan Trench inner slope

*Kazuko USAMI1, Ken IKEHARA1, Toshiya KANAMATSU2, Cecilia McHugh3 (1.Geological Survey of Japan, AIST, 2.JAMSTEC, 3.Queens College, C.U.N.Y)

Keywords:earthquake, Japan Trench, turbidite, tephra, 14C age

We conducted radiocarbon age determinations for bulk organic carbon of piston core sediment samples, recovered from the mid slope terrace on the Japan Trench inner slope, 36.6-40.8 N, 142.8-144.2 E, water depth 4203-6217 m, during the NT13-19 and YK14-E01 cruises. The obtained conventional radiocarbon ages are assumed to be almost 2000 years older than actual ages based on the ages of the core top samples and of the intercalated age-known tephras.
Many deep-sea turbidites were intercalated in the cores. They are considered to be seismo-turbidites regarding the sedimentary structures, grain compositions and surrounded topographic conditions. Age differences between hemipelagic and turbidite muds suggest that remobilization of surface sediments by the earthquake is the important process for turbidite deposition on the terrace.