T209 Ridge to Trench Evolution of Oceanic Lithosphere and Its Accretion Tectonics in the Pacific Rim (Past and Present) (Posters)

Tuesday, 21 October 2014
9:00 AM - 6:30 PM
Exhibition Hall C

A PALEOSEISMOLOGICAL STUDY OF DEEP-SEA SEDIMENTS COLLECTED FROM THE SAGAMI TROUGH IN CENTRAL JAPAN

Paper number: T209-10
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Large earthquakes of the plate boundary type have occurred repeatedly in the Kanto region including the Tokyo district, central Japan. This region has uplifted and subsided progressively during these earthquakes.The recurrence intervals of the large earthquake would be 200-300 yrs and/or 2000 yrs (Shishikura, 2012). The earthquake history also could be recorded in the deep-sea sediment (Ikehara, 2012), but it is generally difficult to identify the earthquake event deposit from any other event deposits (e.g. flood deposits). Noda et al. (2008) suggested that we could exclude mostly flood deposits by careful choosing of sampling sites.

In this study, we collected deep-sea sediments from west Sagami Bay, where the earthquake event sediments in this region might be deposited. Two piston core samples were collected from a gentle submarine slope of KT-12-35 PC01 (991 m in water depth) and KT-12-35 PC03 (1,235 m in water depth). A submarine fan is formed on the gentle submarines slope (Ikehara, 2012). The fan deposit might be transported from a steep fault cliff, where is located the west side of the coring site. We discuss a general sedimentary process in this region and try to extract the earthquake history from these core samples.