It coincides with the day Japan’s first volcano observatory was set up in 1911 on Mount Asamayama, which straddles Gunma and Nagano prefectures. The Sekotsuji district of Fuji in Shizuoka ...

The four-stage classification system is intended to be used in other areas where a potential eruption could occur, such as Mount Usu in Hokkaido, Mount Asamayama, straddling Nagano and Gunma ...