An active volcano in Japan produced a major landslide, resulting in a more than 8 mile long path of destruction with many areas being inundated by more than 50 meters or 164 feet thick of mud and debris. This occurred on the southern flank of the Mount Ontake volcano, which today's video will discuss in detail. Factors that caused this 1984 landslide disaster which will be discussed include a major earthquake, strike slip faulting, recent rainfall, and ground amplification.
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A special thanks to the EarthquakeSim YouTube channel for granting me permission to use clips of his footage!
Video Sources from the EarthquakeSim YouTube channel:
[1] https://www.youtube.com/watch?v=RLCEDINUFao
[2] https://www.youtube.com/watch?v=2mwp-qKkJPA
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Sources/Citations:
[1] Japanese Meteorological Agency
[2] Endo, K., Sumita, M., Machida, M., Furuichi, M. (1989). The 1984 Collapse and Debris Avalanche Deposits of Ontake Volcano, Central Japan. In: Latter, J.H. (eds) Volcanic Hazards. IAVCEI Proceedings in Volcanology, vol 1. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-73759-6_14
[3] OOIDA, Tooru & YAMAZAKI, Fumihito & FUJII, Iwao & AOKI, Harumi. (1989). Aftershock activity of the 1984 western Nagano Prefecture earthquake, central Japan, and its relation to earthquake swarms. Journal of Physics of the Earth. 37. 401-416. 10.4294/jpe1952.37.401.
[4] Mimura, K. & Kano, Kazuhiko & Nakano, S. & Hoshizumi, H.. (2016). Ontake debris avalanche in 1984—Flow and deposition mechanism inferred from the deposit—.. Bulletin of the Geological Survey of Japan. 39. 495-523.
[5] Iwata, Naoki & Kiyota, Ryouji & Aydan, Ömer. (2021). 3D Strong Motion Simulation of the 1984 Western Nagano Prefecture Earthquake and Its Implication on Ontake Volcano Landslide. 10.1007/978-3-030-64518-2_72.
[6] Miyagi, I., Geshi, N., Hamasaki, S. et al. Heat source of the 2014 phreatic eruption of Mount Ontake, Japan. Bull Volcanol 82, 33 (2020). https://doi.org/10.1007/s00445-020-1358-x, CC BY 4.0.
[7] U.S. Geological Survey
[8] Oikawa, T., Yoshimoto, M., Nakada, S. et al. Reconstruction of the 2014 eruption sequence of Ontake Volcano from recorded images and interviews. Earth Planet Sp 68, 79 (2016). https://doi.org/10.1186/s40623-016-0458-5. CC BY 4.0.
[9] Tsunematsu, Kae & Ishimine, Yasuhiro & Kaneko, Takayuki & Yoshimoto, Mitsuhiro & Fujii, Toshitsugu & Yamaoka, Koshun. (2016). Estimation of ballistic block landing energy during 2014 Mount Ontake eruption. Earth, Planets and Space. 68. 10.1186/s40623-016-0463-8. CC BY 4.0.
The above two sources were used to map the locations of 1979 eruption vents and 2014 eruption source vents and extent of pyroclastic flows.
[10] Kato, Aitaro & Terakawa, Toshiko & Yamanaka, Yoshiko & Maeda, Yuta & Horikawa, Shinichiro & Matsuhiro, Kenjiro & Okuda, Takashi. (2015). Preparatory and precursory process leading up to the 2014 phreatic eruption of Mount Ontake, Japan. Earth, Planets and Space. 67. 10.1186/s40623-015-0288-x. CC BY 4.0.
0:00 Solid Ground
0:29 Major Earthquake
1:56 Landslide Path
3:37 Landslide Formed Lake
4:02 Damage & Extent
4:33 Seismic Amplification