Sector collapse of Mayuyama lava dome occurred in 1792 eruption
Mayuyama lava dome, situated at west of Shimabara city, were collpased by strong earthquakes at the end of Fugendake eruption. Debris generated of this collapse were descended as large avalanche, and destroyed completely southern part of Shimabara city. A part of debris dashed into Ariake Sea, and then caused huge Tsunami. The Tsunami were attacked not olny the sea shore of Shimabara Peninsula but also Kumamoto area where is the opposite site of Shimabara town. The victims of this disaster is estimated as 150,000 people, which is the worst volcanic disaster in Japan in historic time.
From the Nita park, steep cliff generated by sector collapse of Mayuyama lava dome can be observed (under left of photograph). From Chichibugaura park, hummocky hills were eroded by sea waves and its section can be observed.