[S-VC47] Volcanic and igneous activities, and these long-term forecasting

[SVC47-02] The 1649 AD pyroclastic fall deposits of Nikko-Shirane Volcano

*Yuki Kusano¹, Teruki Oikawa¹, Yoshihiro Ishizuka¹ (1.Geological Survey of Japan, AIST)

Keywords:Nikko-Shirane Volcano, 1649 calAD, pyroclastic fall deposit, Volume

Nikko-Shirane Volcano is an active volcano on the border between Gunma and Tochigi prefectures. The largest eruption on historic record occurred in 1649 AD. Eruption products of the 1649 AD eruption are correlated with a muddy-pyroclastic fall deposit below the surface soil at the foot of Nikko-Shirane Volcano (Okuno, 1993; Suzuki et al., 1994). Recently, we conducted six trench surveys around the summit of Nikko-Shirane Volcano and detected the 1649 AD eruption product (Kusano and Ishizuka, 2020). Based on the stratigraphy, thickness, grain size and composition of pyroclastic fall deposit, we will present the summary the eruption products and volume of the 1649 eruption. According to three estimation methods of the eruption volume by Geshi et al. (2010), Hayakawa (1985) and Fierstein and Nathenson (1992), evaluated volume of this eruption is at least 2–3 × 10⁷ m³ which is one digit larger than the estimation before (Okuno, 1993).