Mount Ontake, thought to be inactive, had a series of eruptions in 1980. In 1981, the caldera lake volcano Lake Shikotsu erupted in Hokkaidō, followed in 1982 by Mount Tarumae, which is located on its shores. Mount Kusatsu-Shirane in Kusatsu, Gunma Prefecture, erupted in 1983. The Kaitoku Seamount erupted in 1984, Mount Tokachi—located in Hokkaidō—and Izu-Tobu—located on the Izu Peninsula—erupted in 1989.