The aftermath of the eruption of Mount Unzen was an earthquake and a landslide followed by a tsunami. The event, which resulted in the deaths of over 15,000 people, is considered the worst volcanic disaster in Japanese history.
Mount Unzen, located on the island of Kyushu in southern Japan, is made up of a number of stratovolcanoes, also known as composite volcanoes, which are characterized by explosive eruptions. In late 1791, a series of earthquakes shook the western slope of the mountain. One of its peaks, Fugen-dake, erupted in early 1792, causing lava to flow from the volcano for two months. In May 1792, two further earthquakes hit the area, possibly accompanied by an eruption of Mount Unzen's dome. The eastern slope of the mountain collapsed, causing an enormous landslide that decimated the city of Shimabara and flowed into the sea. This triggered a huge tsunami that grew to a maximum height of 187 feet, which first struck the far side of Ariake Bay in Higo Province and then returned and hit the already devastated city of Shimabara.
In 1991, Mount Unzen erupted again, resulting in the evacuation and destruction of thousands of homes and the deaths of 43 people. The eruption was followed by a number of earthquakes, minor eruptions and lava flows that continued until 1996. The history of the 1792 catastrophe causes continuing anxiety over seismic and volcanic activity in the area.