Holocene debris flow assessment based on late Pleistocene to Holocene sediments

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K18526
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Geography, Cultural anthropology, Folklore, and related fields
• Research Institution: Nagoya University
• Principal Investigator: Hori Kazuaki 名古屋大学, 環境学研究科, 准教授 (70373074)
• Project Period (FY): 2017-06-30 – 2019-03-31
• Keywords: 土石流 / 沖積層 / 完新世 / 養老山地 / 濃尾平野

Outline of Final Research Achievements

This study focuses on the late Pleistocene to Holocene sediments near the terminal of fans in the eastern edge of the Yoro Mountain in the western margin of the Nobi Plain and tried to evaluate the past debris flow events. A total of four borehole core sediments obtained in and around the terminal of the fans of Oguradani, Hannyadani, and Tokudadani was analyzed. In the core sediments collected from Tokudadani and Hannyadani, several gravel layers thought to have been deposited due to floods or debris flows were identified. Radiocarbon dating of organic matter and shell fragments could estimate the depositional age of the gravel layers.

Free Research Field

地理学

Academic Significance and Societal Importance of the Research Achievements

豪雨や地震が多発し，山地の多い日本は土石流による物的・人的被害を頻繁に受けてきたが，過去の土石流については発生時期や頻度，規模など不明な点が多い．本研究によって，洪水や土石流によって堆積したと考えられる礫層が確認され，その堆積時期を推定できたことにより，過去の洪水や土石流に関する理解が進むと考えられる．また，研究成果は，山地と低地の境界付近に分布する扇状地の形成過程，とくに扇状地の海水準変動や気候変動に対する応答，の解明にも貢献するものである．