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  • 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

    Series of earthquakes occurred on the western flank of Mount Unzen which gradually moved towards Fugen-dake

    Mount Unzen, Japan
    1791

    Towards the end of 1791, a series of earthquakes occurred on the western flank of Mount Unzen which gradually moved towards Fugen-dake (one of Mount Unzen's peaks).




  • Japan
    Feb, 1792

    Fugen-dake started to erupt

    Japan
    Feb, 1792

    In February 1792, Fugen-dake started to erupt, triggering a lava flow which continued for two months. Meanwhile, the earthquakes continued, shifting nearer to the city of Shimabara.




  • 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.




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