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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Megatsunami | 6/10 | https://en.wikipedia.org/wiki/Megatsunami | reference | science, encyclopedia | 2026-05-05T07:35:36.838495+00:00 | kb-cron |
The massive explosion of Krakatoa created pyroclastic flows which generated megatsunamis when they hit the waters of the Sunda Strait on 27 August 1883. The waves reached heights of up to 24 metres (79 feet) along the south coast of Sumatra and up to 42 metres (138 feet) along the west coast of Java. The tsunamis were powerful enough to kill over 30,000 people, and their effect was such that an area of land in Banten had its human settlements wiped out, and they never repopulated. (This area rewilded and was later declared a national park.) The steamship Berouw, a colonial gunboat, was flung over a mile (1.6 km) inland on Sumatra by the wave, killing its entire crew. Two thirds of the island collapsed into the sea after the event. Groups of human skeletons were found floating on pumice numerous times, up to a year after the event. The eruption also generated what is often called the loudest sound in history, which was heard 4,800 kilometres (3,000 mi; 2,600 nmi) away on Rodrigues in the Indian Ocean.
==== 1905: Lovatnet, Norway ==== On 15 January 1905, a landslide on the slope of the mountain Ramnefjellet with a volume of 350,000 cubic metres (460,000 cu yd) fell from a height of 500 metres (1,600 ft) into the southern end of the lake Lovatnet in Norway, generating three megatsunamis of up to 40.5 metres (133 ft) in height. The waves destroyed the villages of Bødal and Nesdal near the southern end of the lake, killing 61 people – half their combined population – and 261 farm animals and destroying 60 houses, all the local boathouses, and 70 to 80 boats, one of which – the tourist boat Lodalen – was thrown 300 metres (1,000 ft) inland by the last wave and wrecked. At the northern end of the 11.7-kilometre (7.3 mi) long lake, a wave measured at almost 6 metres (20 ft) destroyed a bridge.
==== 1905: Disenchantment Bay, Alaska ==== On 4 July 1905, an overhanging glacier – since known as the Fallen Glacier – broke loose, slid out of its valley, and fell 300 metres (1,000 ft) down a steep slope into Disenchantment Bay in Alaska, clearing vegetation along a path 0.8 kilometres (0.5 mi) wide. When it entered the water, it generated a megatsunami which broke tree branches 34 metres (110 ft) above ground level 0.8 kilometres (0.5 mi) away. The wave killed vegetation to a height of 20 metres (65 ft) at a distance of 5 kilometres (3 mi) from the landslide, and it reached heights of 15 to 35 metres (50 to 115 ft) at different locations on the coast of Haenke Island. At a distance of 24 kilometres (15 mi) from the slide, observers at Russell Fjord reported a series of large waves that caused the water level to rise and fall 5 to 6 metres (15 to 20 ft) for a half-hour.
==== 1934: Tafjorden, Norway ==== On 7 April 1934, a landslide on the slope of the mountain Langhamaren with a volume of 3,000,000 cubic metres (3,900,000 cu yd) fell from a height of about 730 metres (2,395 ft) into the Tafjorden in Norway, generating three megatsunamis, the last and largest of which reached a height of between 62 and 63.5 metres (203 and 208 ft) on the opposite shore. Large waves struck Tafjord and Fjørå. At Tafjord, the last and largest wave was 17 metres (56 ft) tall and struck at an estimated speed of 160 kilometres per hour (100 mph), flooding the town for 300 metres (328 yd) inland and killing 23 people. At Fjørå, waves reached 13 metres (43 ft), destroyed buildings, removed all soil, and killed 17 people. Damaging waves struck as far as 50 kilometres (31 mi) away, and waves were detected at a distance of 100 kilometres (62 mi) from the landslide. One survivor suffered serious injuries requiring hospitalization.
==== 1936: Lovatnet, Norway ==== On 13 September 1936, a landslide on the slope of the mountain Ramnefjellet with a volume of 1,000,000 cubic metres (1,300,000 cu yd) fell from a height of 800 metres (3,000 ft) into the southern end of the lake Lovatnet in Norway, generating three megatsunamis, the largest of which reached a height of 74 metres (243 ft). The waves destroyed all farms at Bødal and most farms at Nesdal – completely washing away 16 farms – as well as 100 houses, bridges, a power station, a workshop, a sawmill, several grain mills, a restaurant, a schoolhouse, and all boats on the lake. A 12.6-metre (41 ft) wave struck the southern end of the 11.7-kilometre (7.3 mi) long lake and caused damaging flooding in the Loelva River, the lake's northern outlet. The waves killed 74 people and severely injured 11.
==== 1936: Lituya Bay, Alaska ==== On 27 October 1936, a megatsunami occurred in Lituya Bay in Alaska with a maximum run-up height of 150 metres (490 ft) in Crillon Inlet at the head of the bay. The four eyewitnesses to the wave in Lituya Bay itself all survived and described it as between 30 and 76 metres (100 and 250 ft) high. The maximum inundation distance was 610 metres (2,000 ft) inland along the north shore of the bay. The cause of the megatsunami remains unclear, but may have been a submarine landslide.
==== 1958: Lituya Bay, Alaska, US ====
On 9 July 1958, a giant landslide at the head of Lituya Bay in Alaska, caused by an earthquake, generated a wave that washed out trees to a maximum elevation of 520 metres (1,710 ft) at the entrance of Gilbert Inlet. The wave surged over the headland, stripping trees and soil down to bedrock, and surged along the fjord which forms Lituya Bay, destroying two fishing boats anchored there and killing two people. This was the highest wave of any kind ever recorded. The subsequent study of this event led to the establishment of the term "megatsunami," to distinguish it from ordinary tsunamis.