1792 Unzen earthquake and tsunami
Encyclopedia
1792 Unzen earthquake and tsunami was an earthquake resulting 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 tsunami, killing 15,000 people altogether. It was also called, Shimabara
erupted, 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 away across the Ariake Sea
).
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 the Mount Unzen's peaks). 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. 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 an avalanche which swept through Shimabara
and into Ariake Bay, triggering a great tsunami.
city, Nagasaki Prefecture
which was created at the destruction of Mayuyama with the pouring of underground water. It size was first 1 km (south-north)and 300m 400m(east to west), but the production of a water exit river made it smaller and it is now 200 m by 70 m.
, there are 99 islands or Kujyu Kushima distributed from Sasebo
city to Hirado city. These islands are different from Tsukumojima.
Mount Unzen
is an active volcanic group of several overlapping stratovolcanoes, near the city of Shimabara, Nagasaki Prefecture, on the island of Kyūshū, Japan’s southernmost main island....
(in the Shimabara Peninsula of Nagasaki Prefecture
Nagasaki Prefecture
is a prefecture of Japan located on the island of Kyūshū. The capital is the city of Nagasaki.- History :Nagasaki Prefecture was created by merging of the western half of the former province of Hizen with the island provinces of Tsushima and Iki...
, 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 tsunami, killing 15,000 people altogether. It was also called, Shimabara
Shimabara
Shimabara can refer to any of the following:* Shimabara, Nagasaki, a city in Nagasaki Prefecture, Japan* Shimabara Peninsula, the geographic feature that hosts Shimabara, Nagasaki* Shimabara Castle, in Shimabara, Nagasaki...
erupted, Higo affected (島原大変肥後迷惑), since many people were killed by this tsunami in Higo, (Kumamoto Prefecture
Kumamoto Prefecture
is a prefecture of Japan located on Kyushu Island. The capital is the city of Kumamoto.- History :Historically the area was called Higo Province; and the province was renamed Kumamoto during the Meiji Restoration. The creation of prefectures was part of the abolition of the feudal system...
, situated 20 km away across the Ariake Sea
Ariake Sea
The is a body of salt water surrounded by Fukuoka, Saga, Nagasaki, and Kumamoto Prefectures, all of which lie on the island of Kyūshū in Japan. It is the largest bay in Kyūshū. Its deepest point is only about 50 m deep, and extreme tides exceed 4 m. It is used for aquaculture, with nori...
).
Volcanic Activities
Shimabara
Shimabara can refer to any of the following:* Shimabara, Nagasaki, a city in Nagasaki Prefecture, Japan* Shimabara Peninsula, the geographic feature that hosts Shimabara, Nagasaki* Shimabara Castle, in Shimabara, Nagasaki...
and into Ariake Bay, triggering a great tsunami.
Tsunami
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 is 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 330 ft (100 m), classing this tsunami as a small megatsunami.Monuments
As of July, 1991, the following monuments have been found.| Kind of Monument | Kumamoto Prefecture | Nagasaki Prefecture | Total |
|---|---|---|---|
| Memorial monument | 43 | 41 | 84 |
| Tsunami border monument | 5 | 0 | 5 |
| Graves | 16 | 90 | 106 |
| Simple monument | 1 | 0 | 1 |
| Others | 9 | 3 | 12 |
| Total | 74 | 134 | 208 |
Shirachi-ko
Shirachi pond(lake) is a pond in ShimabaraShimabara
Shimabara can refer to any of the following:* Shimabara, Nagasaki, a city in Nagasaki Prefecture, Japan* Shimabara Peninsula, the geographic feature that hosts Shimabara, Nagasaki* Shimabara Castle, in Shimabara, Nagasaki...
city, Nagasaki Prefecture
Nagasaki Prefecture
is a prefecture of Japan located on the island of Kyūshū. The capital is the city of Nagasaki.- History :Nagasaki Prefecture was created by merging of the western half of the former province of Hizen with the island provinces of Tsushima and Iki...
which was created at the destruction of Mayuyama with the pouring of underground water. It size was first 1 km (south-north)and 300m 400m(east to west), but the production of a water exit river made it smaller and it is now 200 m by 70 m.
99 Islets(Tsukumojima)
As a result of the destruction, tsukumojima or 99 islets or rocks were distributed before Shimabara city. In the same Nagasaki PrefectureNagasaki Prefecture
is a prefecture of Japan located on the island of Kyūshū. The capital is the city of Nagasaki.- History :Nagasaki Prefecture was created by merging of the western half of the former province of Hizen with the island provinces of Tsushima and Iki...
, there are 99 islands or Kujyu Kushima distributed from Sasebo
Sasebo
Sasebo or may refer to:* Sasebo, Nagasaki, a city in Japan and a base of the Imperial Japanese Navy in the city, later of the Japan Maritime Self-Defense Force* United States Fleet Activities Sasebo, a post-WWII United States Navy Base in the city...
city to Hirado city. These islands are different from Tsukumojima.