5.8 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Megatsunami | 5/10 | https://en.wikipedia.org/wiki/Megatsunami | reference | science, encyclopedia | 2026-05-05T07:35:36.838495+00:00 | kb-cron |
=== Historic ===
==== c. 2000 BC: Réunion ==== A landslide on Réunion island, to the east of Madagascar, may have caused a megatsunami.
==== c. 1600 BC: Santorini ====
The Thera volcano erupted, the force of the eruption causing megatsunamis which affected the whole Aegean Sea and the eastern Mediterranean Sea.
==== c. 1100 BC: Lake Crescent ==== An earthquake generated the 7,200,000-cubic-metre (9,400,000 cu yd) Sledgehammer Point Rockslide, which fell from Mount Storm King in what is now Washington in the United States and entered waters at least 140 metres (459 ft) deep in Lake Crescent, generating a megatsunami with an estimated maximum run-up height of 82 to 104 metres (269 to 341 ft).
=== Modern ===
==== 1674: Ambon Island, Banda Sea ====
On 17 February 1674, between 19:30 and 20:00 local time, an earthquake struck the Maluku Islands. Ambon Island received run-up heights of 100 metres (328 ft), making the wave far too large to be caused by the quake itself. Instead, it was probably the result of an underwater landslide triggered by the earthquake. The quake and tsunami killed 2,347 people.
==== 1731: Storfjorden, Norway ==== At 10:00 p.m. on 8 January 1731, a landslide with a volume of possibly 6,000,000 cubic metres (7,800,000 cu yd) fell from the mountain Skafjell from a height of 500 metres (1,640 ft) into the Storfjorden opposite Stranda, Norway. The slide generated a megatsunami 30 metres (100 ft) in height that struck Stranda, flooding the area for 100 metres (330 ft) inland and destroying the church and all but two boathouses, as well as many boats. Damaging waves struck as far away as Ørskog. The waves killed 17 people.
==== 1741: Oshima-Ōshima, Sea of Japan ====
An eruption of Oshima-Ōshima occurred that lasted from 18 August 1741 to 1 May 1742. On 29 August 1741, a devastating tsunami occurred. It killed at least 1,467 people along a 120-kilometre (75 mi) section of the coast, excluding native residents whose deaths were not recorded. Wave heights for Gankakezawa have been estimated at 34 metres (112 ft) based on oral histories, while an estimate of 13 metres (43 ft) is derived from written records. At Sado Island, over 350 kilometres (217 mi; 189 nmi) away, a wave height of 2 to 5 metres (6 ft 7 in to 16 ft 5 in) has been estimated based on descriptions of the damage, while oral records suggest a height of 8 metres (26 ft). Wave heights have been estimated at 3 to 4 metres (9.8 to 13.1 ft) even as far away as the Korean Peninsula. There is still no consensus in the debate as to what caused it but much evidence points to a landslide and debris avalanche along the flank of the volcano. An alternative hypothesis holds that an earthquake caused the tsunami. The event reduced the elevation of the peak of Hishiyama from 850 to 722 metres (2,789 to 2,369 ft). An estimated 2.4-cubic-kilometre (0.58 cu mi) section of the volcano collapsed onto the seafloor north of the island; the collapse was similar in size to the 2.3-cubic-kilometre (0.55 cu mi) collapse which occurred during the 1980 eruption of Mount St. Helens.
==== 1756: Langfjorden, Norway ==== Just before 8:00 p.m. on 22 February 1756, a landslide with a volume of 12,000,000 to 15,000,000 cubic metres (16,000,000 to 20,000,000 cu yd) travelled at high speed from a height of 400 metres (1,300 ft) on the side of the mountain Tjellafjellet into the Langfjorden about 1 kilometre (0.6 mi) west of Tjelle, Norway, between Tjelle and Gramsgrø. The slide generated three megatsunamis in the Langfjorden and the Eresfjorden with heights of 40 to 50 metres (130 to 160 ft). The waves flooded the shore for 200 metres (660 ft) inland in some areas, destroying farms and other inhabited areas. Damaging waves struck as far away as Veøya, 25 kilometres (16 mi) from the landslide – where they washed inland 20 metres (66 ft) above normal flood levels – and Gjermundnes, 40 kilometres (25 mi) from the slide. The waves killed 32 people and destroyed 168 buildings, 196 boats, large amounts of forest, and roads and boat landings.
==== 1792: Mount Unzen, Japan ====
On 21 May 1792, a flank of the Mayamaya dome of Mount Unzen collapsed after two large earthquakes. This had been preceded by a series of earthquakes coming from the mountain, beginning near the end of 1791. Initial wave heights were 100 metres (330 ft), but when they hit the other side of Ariake Bay, they were only 10 to 20 metres (33 to 66 ft) in height, though one location received 57-metre (187 ft) waves due to seafloor topography. The waves bounced back to Shimabara, which, when they hit, accounted for about half of the tsunami's victims. According to estimates, 10,000 people were killed by the tsunami, and a further 5,000 were killed by the landslide. As of 2011, it was the deadliest known volcanic event in Japan.
==== 1853–1854: Lituya Bay, Alaska ==== Sometime between August 1853 and May 1854, a megatsunami occurred in Lituya Bay in what was then Russian America. Studies of Lituya Bay between 1948 and 1953 first identified the event, which probably occurred because of a large landslide on the south shore of the bay near Mudslide Creek. The wave had a maximum run-up height of 120 metres (394 ft), flooding the coast of the bay up to 230 metres (750 ft) inland.
==== 1874: Lituya Bay, Alaska ==== A study of Lituya Bay in 1953 concluded that sometime around 1874, perhaps in May 1874, another megatsunami occurred in Lituya Bay in Alaska. Probably occurring because of a large landslide on the south shore of the bay in the Mudslide Creek Valley, the wave had a maximum run-up height of 24 metres (80 ft), flooding the coast of the bay up to 640 metres (2,100 ft) inland.
==== 1883: Krakatoa, Sunda Strait ====