Japan Geoscience Union Meeting 2014

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Oral

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

[M-IS33_30AM1] How to evaluate the potential for megaquake and tsunami from onsite observations before the events?

Wed. Apr 30, 2014 9:00 AM - 10:45 AM 501 (5F)

Convener:*Yoshihiro Ito(Disaster Prevention Research Institute, Kyoto University), Kiichiro Kawamura(Graduate School of Sciences and Engineers, Yamaguchi University), Takeshi Tsuji(International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University), Chair:Yoshihiro Ito(Disaster Prevention Research Institute, Kyoto University), Kiichiro Kawamura(Graduate School of Sciences and Engineers, Yamaguchi University), Takeshi Tsuji(International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University)

9:30 AM - 9:45 AM

[MIS33-03] Turbidites collected from the Japan Trench inner slope, during the NT13-19 cruise

*Kazuko USAMI1, Ken IKEHARA1, Cecilia MCHUGH2, Toshiya KANAMATSU3 (1.Geological Survey of Japan, AIST, 2.JAMSTEC / Queens College, C.U.N.Y., 3.JAMSTEC)

Keywords:earthquake, Japan Trench, turbidite, tephra

To understand the recurrence of large earthquakes along the Japan Trench, we collected 24 sediment cores from the Japan Trench inner slope, 37.5-40 N, 143.5-144.16 E, water depth 4000-6000 m, during the NT13-19 cruise. Many deep-sea turbidites were intercalated in the sediment cores. We examined the interval and structures of the turbidites using soft-X radiographs. In general, number of the turbidites in a core is high in the southern part off Sendai, but is low in the northern part off Miyako. Meanwhile, intercalated tephras such as Haruna-Ikaho (Hr-FP), Towada-Chuseri (To-Cu) and Towada-a (To-a) were identified in the 13 cores. Based on the eruption ages of the tephras, we estimated the averaged recurrence intervals of 100-500 years in average in almost cores. But there are cores that display different intervals over 1500-2000 years.