An old lava dome collapses in Kyūshū, Japan when the Mount Unzen volcano, part of Shimabara Peninsula, which has seen extensive volcanism over millions of years, erupts on May 21, 1792; the resulting landslide into Ariake Bay and megatsunami that reaches a height of one hundred meters (three hundred and thirty feet), kills about fourteen thousand three hundred people in and around Shimabara.
It it is the worst volcanic-related eruption in Japan to date.