Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Oral

M (Multidisciplinary and Interdisciplinary) » M-GI General Geosciences, Information Geosciences & Simulations

[M-GI25] Environmental changes in mountainous area

Tue. May 22, 2018 9:00 AM - 10:30 AM A08 (Tokyo Bay Makuhari Hall)

convener:Keisuke Suzuki(Department of Environmental Sciences, Faculty of Science, Shinshu University), Yoshihiko Kariya(Department of Environmental Geography, Senshu University), Chiyuki Narama(新潟大学理学部理学科, 共同), Akihiko SASAKI(Department of Geography and Environmental Studies, Kokushikan University), Chairperson:Kariya Yoshihiko(専修大学)

10:00 AM - 10:15 AM

[MGI25-05] Holocene historical development of mass movement in the Utougi District, the upper Abe River basin, central Japan

*Yoshihiko Kariya1, Yuki Matsushi2, Hiroyuki Matsuzaki3 (1.Department of Environmental Geography, Senshu University, 2.Disaster Prevention Research Institute, Kyoto University, 3.School of Engineering, the University of Tokyo)

Keywords:slope changes, radiocarbon dating, in-situ cosmogenic nuclide exposure dating, mudflow, Trench-type megaquake

The Utougi area has long-term agricultural history of Japanese horseradish (Wasabi). This area is located on the middle flank of the Koma Mountains in central Japan. Unconsolidated thick gravelly deposits in the area showing terrace and fan-like topographies had been sequentially formed by the precede mudflow, the following large-scale rock slope failure, and the eventual debris flow events. According to chronological evidences given by 14C and in-situ terrestrial cosmogenic nuclide methods, these events of slope movement are thought to occur in the period from 6.0 to 3.8 cal ka BP. Megaquakes generated from the Suruga-Nankai submarine troughs south off central Japan are strong candidates for the causes of the events, despite the paucity of historical records and oral tradition. It can be said that the traditional cultivation of Japanese horseradish in the Utougi area has been established on the field formed by mass-movement in a steep mountain area. The Utougi area can provide a good opportunity for considering the relationship between geomorphic development and agricultural history in a montane village.