Challenges of Quaternary geology and oxygen isotope dendrochronology for high precision dating of large-scale landslides

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K01123
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 04010:Geography-related
• Research Institution: Senshu University
• Principal Investigator: Kariya Yoshihiko 専修大学, 文学部, 教授 (70323433)
• Co-Investigator(Kenkyū-buntansha): 山田 隆二 国立研究開発法人防災科学技術研究所, マルチハザードリスク評価研究部門, 主任研究員 (70343762)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 深層崩壊 / 高精度編年 / 酸素同位体比年輪年代 / 地すべり / 歴史地震 / 第四紀 / 地形学

Outline of Final Research Achievements

For the first time, we have attempted to precisely date large-scale slope failures in the Japanese Alps using both Quaternary geology/geomorphology and oxygen isotopic dendrochronology. As a result, we obtained new ages for the Otsukigawa River Debris Avalanche (Koumi Town, Nagano Prefecture), Mount Shichimenzan Rockslide (Hayakawa Town, Yamanashi Prefecture), and Oyakure Rockslide (Shizuoka City, Shizuoka Prefecture) that force a reexamination of the conventional theory. Previous authors have argued that carbon-14 dates and historical documents simply link paleoearthquakes and paleo-rainstorms with large-scale slope failures, but our results show that we should be more careful in such correlations.

Free Research Field

地形学・第四紀学

Academic Significance and Societal Importance of the Research Achievements

本研究は、大規模斜面崩壊の年代決定について、炭素14C年代と史料記載年代との年代範囲の合致だけに頼らず、周到かつ詳細な地形・地質調査と良質な年代測定試料の利用及び様々な年代測定法を適切に組み合わせて総合的に行うことの重要性を示した。この成果は、地形学、第四紀学、斜面防災学、歴史地震学などの諸分野に資するものである。