The 1792 Unzen landslide and tsunami was a volcanic megadisaster, occurring on 21 May 1792, during the Edo period. Triggered by the volcanic activity of Mount Unzen (on the Shimabara Peninsula, Nagasaki Prefecture, Kyushu, Japan), it caused a massive collapse of the Mayuyama lava dome and a subsequent tsunami. Approximately 15,000 people lost their lives, making it the largest scale volcanic disaster in Japanese history. It was also called Shimabara suffered, Higo affected (島原大変肥後迷惑), since many people were killed by this tsunami in Higo (Kumamoto Prefecture, situated 20 km (12.4 mi) across the Ariake Sea).
Why this event still matters
Historical incidents shape the rules that protect people today — building codes, evacuation policy, warning systems and inspection regimes almost always trace back to a specific disaster. Studying 1792 eruption of Mount Unzen alongside current events is how preparedness improves.
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