1:45 PM - 2:00 PM
[SVC32-01] Stratigraphy and formative process of the proximal deposits of the 1707 CE Hoei eruption, Fuji Volcano, based on field geological survey combined with photogrammetry and terrain analysis using aerial photos and LiDAR point cloud
Keywords:Hoeizan, Akaiwa, volcanic geology, terrain analysis, UAV
The1707 Hoei eruption of Fuji Volcano was previously considered to have occurred from a series of craters (Hoei Craters 1-3) on the southeast flank of the volcano, and the yellowish-brown tuffaceous breccia (Akaiwa) exposed near the ridge (Hoeizan) along the eastern rim of Crater 1 was interpreted as older strata uplifted during the eruption, although the evidence was insufficient and questionable. Based on field geological survey combined with a terrain analysis on UAV aerial photos and high-density point cloud data (VIRTUAL SHIZUOKA) obtained by aerial laser survey, we revealed the topography and stratigraphy of the proximal deposits of the Hoei eruption and the detailed eruptive process that formed them, including the location change of the source crater. The above preliminary report has already been presented (Koyama, 2019, JpGU), however, this time the author reports a summary of the revised and expanded results with further analysis and discussion. For details, refer to Koyama (2023, Fujinology, No. 3, Mt. Fuji World Heritage Center, Shizuoka).
1. The stratigraphic division and distribution of the proximal deposits of the Hoei eruption (Units 1-9) by Baba et al. (2022, Bull.Volcanol.Soc.Japan) were revised, and a new division of Units 6A-6C was added.
2. The author also clarified the northward and southwestward lithologic changes of Unit 7, which is distributed near Hoeizan, and reaffirmed that the Hoeizan was formed by the accumulation of pyroclastic material ejected during the Hoei eruption and that the Akaiwa is the product of hydrothermal activity.
3. The depositional structure of Unit 6B was revealed, and the source crater of Units 6A-8 was located at the bottom of Crater 1, and Unit 8 was deposited on the eastern part of the inner wall of Crater 1.
4. The topography and distribution of Units 2-5 were reexamined, and their source crater positions and eruptive sequences were estimated. As a result, the source craters of Unit 2 and Unit 5, which erupted white pumice in the early stage of the eruption, are estimated to be the Gotenniwa East Crater adjacent to the east of Craters 2 and 3.
1. The stratigraphic division and distribution of the proximal deposits of the Hoei eruption (Units 1-9) by Baba et al. (2022, Bull.Volcanol.Soc.Japan) were revised, and a new division of Units 6A-6C was added.
2. The author also clarified the northward and southwestward lithologic changes of Unit 7, which is distributed near Hoeizan, and reaffirmed that the Hoeizan was formed by the accumulation of pyroclastic material ejected during the Hoei eruption and that the Akaiwa is the product of hydrothermal activity.
3. The depositional structure of Unit 6B was revealed, and the source crater of Units 6A-8 was located at the bottom of Crater 1, and Unit 8 was deposited on the eastern part of the inner wall of Crater 1.
4. The topography and distribution of Units 2-5 were reexamined, and their source crater positions and eruptive sequences were estimated. As a result, the source craters of Unit 2 and Unit 5, which erupted white pumice in the early stage of the eruption, are estimated to be the Gotenniwa East Crater adjacent to the east of Craters 2 and 3.