History of 1792 Unzen earthquake and tsunami
Monday May 21, 1792 to May, 1792
Japan
The 1792 Unzen earthquake and tsunami resulted from the volcanic activities of Mount Unzen (in the Shimabara Peninsula of Nagasaki Prefecture, Japan) on 21 May. This caused the collapse of the southern flank of the Mayuyama dome in front of Mount Unzen, resulting in a tremendous megatsunami, killing 15,000 people altogether. It was also called Shimabara erupted, Higo affected, (Shimabara means the central mountain of the Shimabara Peninsula) since many people were killed by this tsunami in Higo (Kumamoto Prefecture, situated 20 km (12 mi) away across the Ariake Sea).Shimabara Peninsula of Nagasaki Prefecture, Japan Tuesday May 21, 1782 Two large earthquakes were followed by a collapse of the eastern flank of Mount Unzen's Mayuyama dome
Shimabara Peninsula of Nagasaki Prefecture, Japan Tuesday May 21, 1782 On the night of 21 May, two large earthquakes were followed by a collapse of the eastern flank of Mount Unzen's Mayuyama dome, causing a landslide which swept through the city of Shimabara and into Ariake Bay, triggering a great tsunami.
Mount Unzen, Japan 1791 Japan Feb, 1792 Shimabara Peninsula of Nagasaki Prefecture, Japan May, 1792 Megatsunami
Shimabara Peninsula of Nagasaki Prefecture, Japan May, 1792 It is not known to this day whether the collapse occurred as a result of an eruption of the dome or as a result of the earthquakes. The tsunami struck Higo Province on the other side of Ariake Bay before bouncing back and hitting Shimabara again. Out of an estimated total of 15,000 fatalities, around 5,000 are thought to have been killed by the landslide, around 5,000 by the tsunami across the bay in Higo Province, and a further 5,000 by the tsunami returning to strike Shimabara. The waves reached a height of 33–66 ft (10–20 m), classing this tsunami as a small megatsunami. At the Osaki-bana point Futsu town, the waves locally grew to a height of 187 ft (57 m) due to the effect of sea bottom topography.