2. A Fatal Landslide and Earth Shattering Tsunami
As the lava kept flowing from Mount Unzen, the earthquakes and tremors continued. On the night of May 21st, 1792, two big quakes hit. They were powerful enough to shake one of the lava domes loose, causing it to collapse down the eastern side of the mountain. That triggered a landslide, which swept through the city of Shimabara down below, and continued on to Ariake Bay.
When the landslide struck the water, it caused a mega tsunami, with waves nearly 70 feet high, rising up to 187 feet high in some places because of the seabed’s topography. The tsunami traveled across Ariake Bay, until it hit the city of Higo on the other side, where it caused widespread devastation. It then bounced back across the bay, and hit the city of Shimabara, where the dust had still not settled from the landslide that had swept through it and triggered the tsunami in the first place. About 15,000 people were killed in the disaster, making it Japan’s worst volcanic eruption.