- ongeveer 65.000.000 jaar geleden botste een meteoriet op Aarde die zorgde voor een massa-instinctie van verschillende organismen zoals de dino's. Ook dit zou (mega) tsunami's opgeleverd hebben.
- Storegga Slide: Ongeveer 6000 vc vond er 3 gigantische landverschuivingen plaats nabij Noorwegen. Dit bracht enkele enorme tsunami's met zich mee die voelbaar moeten geweest zijn in Nederland en België.
- 1628 VC: De Santorini barst uit, een vulkaan op het eiland Santorini die een tsunami moet veroorzaakt hebben van 35 meter hoog.
- 365: Een onderzeese aardbeving nabij Kreta veroorzaakt een grote tsunami die Alexandrië verwoest.
- 1 november 1755: Dit wordt ook wel eens de allerheiligenaardbeving genoemd en deze aardbeving van 9,0 op schaal van Richter veroorzaakte een tsunami van ongeveer 15 meter hoog. Op de plekken die niet getroffen werden door de tsunami ontstond een brand die 5 dagen duurde. Uiteindelijk werd deze tsunami zelfs waargenomen in de Noordzee: In Zuid- Engeland nam men golven waar van 3 meter hoog.
- 27 augustus 1883: De Krakatoa (Indonesië) barst uit. Deze hevige eruptie zorgt ervoor dat de vulkaan ineenstort. Op het eiland zelf waren er pyroclastische stromen en door de ineenzakking van de vulkaan onstond een tsunami die aan 30.000 mensen het leven koste. De tsunami zou een hoogte gehad hebben van 30 meter.
- 28 december 1908: In de staart van Messina vond een aardbeving plaats die leidde tot een onderzeese aardverschuiving. Hierbij ontstond ook een tsunami die Messina zelf hebben verwoest.
- 1 april 1946: Neen, dit is geen aprilgrap maar op deze datum was er een aardbeving nabij Alaska die zorgde voor een tsunami. Hierna werd het eerste tsunami waarschuwingssysteem opgericht.
- 22 mei 1960: Op deze dag werd de zwaarste aardbeving ooit waargenomen: 9,5 op schaal van Richter. Dit was in Chili. De tsunami werd een dag later waargenomen in Japan, aan de andere kant van de wereld. De golf zou 2500 doden hebben veroorzaakt.
- 27 maart 1964: In Alaska werd die dag een aardbeving waargenomen van 9,2 op schaal van Richter. Ook dit ging gepaard met een golf van 67 meter. Dit zou de hoogste tsunami moeten geweest zijn die ooit is waargenomen.
- 17 juli 1998: Aardbeving van 7,7 op schaal van Richter nabij Papoea-Nieuw-Guinea zorgt voor een tsunami van 7 tot 10 meter wat bijzonder groot is voor een aardbeving van deze sterkte. De golf zorgde ook voor een opvallend groot aantal doden: 12.000.
- 26 december 2004: Deze ligt nog vers in uw geheugen: een aardbeving van 9,1 op schaal van Richter zorgde voor golven van 10 meter hoog in de Indische oceaan. Het hypocentrum (de plaats waar de aardbeving letterlijk plaatsvond) lag 10 km diep in de zee nabij Sumatra. Bijna alle landen van de Indische oceaan werden getroffen: Sri-Lanka, India, Thailand, ... In totaal vielen er 250.000 doden en dat maakt dit de dodelijkste tsunami die ooit is waargenomen.
- 17 juli 2006: Opnieuw in de Indische oceaan vond er een zware aardbeving plaats van 7,2 op schaal van Richter. Dit ging gepaard met golven van 3 meter: er vielen 650 doden en 7200 gewonden.
- De voorlopig laatste tsunami van betekenis vond plaats op 11 maar 2011 nabij Sendaï. De golf werd veroorzaakt door een aardbeving van 9,0 op schaal van Richter. Hij was 15 meter hoog en verwoestte vele delen van Japan. Er vielen ongeveer 40.000 doden. De beving was de zwaarste die ooit is waargenomen in Japan. Dan zijn we op het einde van mijn onvolledig overzicht gekomen. Als jullie zien dat er iets ontbreekt dan mag je dat er altijd bijzetten in een bericht onder dit artikel.
Geraadpleegde bronnen: diverse artikelen van wikipedia
Auteur: Stormchaser5000 | Gewijzigd: 18 oktober 2015, 22:00 uur, door BertD
Tropische dagen 2019: 13 (warmste dag: 25 juli 2019 met 41,5°C)
Onweersdagen 2020: -
Tropische dagen 2020: -
Hoogste temperatuur 2020: -
Lisbon, Portugal - 1 November 1755
A magnitude 8.5 earthquake caused a series of three huge waves to strike various towns along the west coast of Portugal and southern Spain, up to 30 m high, in some places. The tsunami affected waves as far away as Carlisle Bay, Barbados, where waves were said to rise by 1.5 m. The earthquake and ensuing tsunami killed 60,000 in the Portugal, Morocco and Spain.
Enshunada Sea, Japan - 20 September 1498
An earthquake, estimated to have been at least magnitude 8.3, caused tsunami waves along the coasts of Kii, Mikawa, Surugu, Izu and Sagami. The waves were powerful enough to breach a spit, which had previously separated Lake Hamana from the sea. There were reports of homes flooding and being swept away throughout the region, with a total of at least 31,000 people killed.
Nankaido, Japan - 28 October 1707
A magnitude 8.4 earthquake caused sea waves as high as 25 m to hammer into the Pacific coasts of Kyushyu, Shikoku and Honshin. Osaka was also damaged. A total of nearly 30,000 buildings were damaged in the affected regions and about 30,000 people were killed. It was reported that roughly a dozen large waves were counted between 3 pm and 4 pm, some of them extending several kilometres inland at Kochi.
Sanriku, Japan - 15 June 1896
This tsunami propagated after an estimated magnitude 7.6 earthquake occurred off the coast of Sanriku, Japan. The tsunami was reported at Shirahama to have reached a height of 38.2 m, causing damage to more than 11,000 homes and killing some 22,000 people. Reports have also been found that chronicle a corresponding tsunami hitting the east coast of China, killing around 4000 people and doing extensive damage to local crops.
Northern Chile - 13 August 1868
This tsunami event was caused by a series of two significant earthquakes, estimated at a magnitude of 8.5, off the coast of Arica, Peru (now Chile). The ensuing waves affected the entire Pacific Rim, with waves reported to be up to 21 m high, which lasted between two and three days. The Arica tsunami was registered by six tide gauges, as far off as Sydney, Australia. A total of 25,000 deaths and an estimated US$300 million in damages were caused by the tsunami and earthquakes combined along the Peru-Chile coast.
Ryuku Islands, Japan - 24 April 1771
A magnitude 7.4 earthquake is believed to have caused a tsunami that damaged a large number of islands in the region; however, the most serious damage was restricted to Ishigaki and Miyako Islands. It is commonly cited that the waves that struck Ishigaki Island was 85.4 m high, but it appears this is due to a confusion of the original Japanese measurements, and is more accurately estimated to have been around 11 to 15 m high. The tsunami destroyed a total of 3,137 homes, killing nearly 12,000 people in total.
Ise Bay, Japan - 18 January 1586
The earthquake that caused the Ise Bay tsunami is best estimated as being of magnitude 8.2. The waves rose to a height of 6 m, causing damage to a number of towns. The town of Nagahama experienced an outbreak of fire as the earthquake first occurred, destroying half the city. It is reported that the nearby Lake Biwa surged over the town, leaving no trace except for the castle. The Ise Bay tsunamis caused more than 8000 deaths and a large amount damage.
Edit Joyce: link even aanklikbaar gemaakt
| Gewijzigd: 19 oktober 2015, 09:26 uur, door Joyce.s
Signs of ancient mega-tsunami could portend modern hazard
Evidence of an 800-foot wave in the Cape Verde Islands
Geologists think the eastern flank of the Cape Verde islands' Fogo volcano crashed into the sea some 73,000 years ago, leaving this giant scar, and generating a gigantic tsunami.
Credit: Satellite image from NASA
Scientists working off west Africa in the Cape Verde Islands have found evidence that the sudden collapse of a volcano there tens of thousands of years ago generated an ocean tsunami that dwarfed anything ever seen by humans. The researchers say an 800-foot wave engulfed an island more than 30 miles away. The study could revive a simmering controversy over whether sudden giant collapses present a realistic hazard today around volcanic islands, or even along more distant continental coasts. The study appears today in the journalScience Advances.
"Our point is that flank collapses can happen extremely fast and catastrophically, and therefore are capable of triggering giant tsunamis," said lead author Ricardo Ramalho, who did the research as a postdoctoral associate at Columbia University's Lamont-Doherty Earth Observatory, where he is now an adjunct scientist. "They probably don't happen very often. But we need to take this into account when we think about the hazard potential of these kinds of volcanic features."
The apparent collapse occurred some 73,000 years ago at the Fogo volcano, one of the world's largest and most active island volcanoes. Nowadays, it towers 2,829 meters (9,300 feet) above sea level, and erupts about every 20 years, most recently last fall. Santiago Island, where the wave apparently hit, is now home to some 250,000 people.
There is no dispute that volcanic flanks present a hazard; at least eight smaller collapses have occurred in Alaska, Japan and elsewhere in the last several hundred years, and some have generated deadly tsunamis. But many scientists doubt whether big volcanoes can collapse with the suddenness that the new study suggests. Rather, they envision landslides coming in gradual stages, generating multiple, smaller tsunamis. A 2011 French study also looked at the Fogo collapse, suggesting that it took place somewhere between 124,000-65,000 years ago; but that study says it involved more than one landslide. The French researchers estimate that the resulting multiple waves would have reached only 45 feet--even at that, enough to do plenty of harm today.
A handful of previous other studies have proposed much larger prehistoric collapses and resulting megatsunamis, in the Hawaiian islands, at Italy's Mt. Etna, and the Indian Ocean's Reunion Island. But critics have said these examples are too few and the evidence too thin. The new study adds a new possible example; it says the estimated 160 cubic kilometers (40 cubic miles) of rock that Fogo lost during the collapse was dropped all at once, resulting in the 800-foot wave. By comparison, the biggest known recent tsunamis, which devastated the Indian Ocean's coasts in 2004 and eastern Japan in 2011, reached only about 100 feet. (Like most other well documented tsunamis, these were generated by movements of undersea earthquake faults--not volcanic collapses.)
Santiago Island lies 55 kilometers (34 miles) from Fogo. Several years ago, Ramalho and colleagues were working on Santiago when they spotted unusual boulders lying as far as 2,000 feet inland and nearly 650 feet above sea level. Some are as big as delivery vans, and they are utterly unlike the young volcanic terrain on which they lie. Rather, they match marine-type rocks that ring the island's shoreline: limestones, conglomerates and submarine basalts. Some weigh up to 770 tons. The only realistic explanation the scientists could come up with: A gigantic wave must have ripped them from the shoreline and lofted them up. They derived the size of the wave by calculating the energy it would have taken to accomplish this feat.
To date the event, in the lab Ramalho and Lamont-Doherty geochemist Gisela Winckler measured isotopes of the element helium embedded near the boulders' surfaces. Such isotopes change depending on how long a rock has been lying in the open, exposed to cosmic rays. The analyses centered around 73,000 years--well within the earlier French estimate of a smaller event. The analysis "provides the link between the collapse and impact, which you can make only if you have both dates," said Winckler.
Tsunami expert Bill McGuire, a professor emeritus at University College London who was not involved in the research, said the study "provides robust evidence of megatsunami formation [and] confirms that when volcanoes collapse, they can do so extremely rapidly." Based on his own work, McGuire s says that such megatsunamis probably come only once every 10,000 years. "Nonetheless," he said, "the scale of such events, as the Fogo study testifies, and their potentially devastating impact, makes them a clear and serious hazard in ocean basins that host active volcanoes."
Ramalho cautions that the study should not be taken as a red flag that another big collapse is imminent here or elsewhere. "It doesn't mean every collapse happens catastrophically," he said. "But it's maybe not as rare as we thought."
In the early 2000s, other researchers started publishing evidence that the Cape Verdes could generate large tsunamis. Others have argued that Spain's Canary Islands have already done so. Simon Day, a senior researcher at University College London has sparked repeated controversy by warning that any future eruption of the Canary Islands' active Cumbre Vieja volcano could set off a flank collapse that might form an initial wave 3,000 feet high. This, he says, could erase more than nearby islands. Such a wave might still be 300 feet high when it reached west Africa an hour or so later he says, and would still be 150 feet high along the coasts of North and South America. So far, such studies have raised mainly tsunamis of publicity, and vigorous objections from other scientists that such events are improbable. A 2013 study of deep-sea sediments by the United Kingdom's National Oceanography Centre suggests that the Canaries have probably mostly seen gradual collapses.
Part of the controversy hangs not only on the physics of the collapses themselves, but on how efficiently resulting waves could travel. In 1792, part of Japan's Mount Unzen collapsed, hitting a series of nearby bays with waves as high as 300 feet, and killing some 15,000 people. On July 9, 1958, an earthquake shook 90 million tons of rock into Alaska's isolated Lituya Bay; this created an astounding 1,724-foot-high wave, the largest ever recorded. Two fishermen who happened to be in their boat that day were carried clear over a nearby forest; miraculously, they survived.
These events, however, occurred in confined spaces. In the open ocean, waves created by landslides are generally thought to lose energy quickly, and thus to pose mainly a regional hazard. However, this is based largely on modeling, not real-world experience, so no one really knows how fast a killer wave might decay into a harmless ripple. In any case, most scientists are more concerned with tsunamis generated by undersea earthquakes, which are more common. When seabed faults slip, as they did in 2004 and 2011, they shove massive amounts of water upward. In deep water, this shows up as a mere swell at the surface; but when the swell reaches shallower coastal areas, its energy concentrates into in a smaller volume of water, and it rears up dramatically. The 2004 Indian Ocean earthquake and tsunami killed 230,000 people in 14 countries; the 2011 Tohoku event killed nearly 20,000 in Japan, and has caused a long-term nuclear disaster.
James Hunt, a tsunami expert at the United Kingdom's National Oceanography Centre who was not involved in the study, said the research makes it clear that "even modest landslides could produce high-amplitude anomalous tsunami waves on opposing island coastlines." The question, he said, "is whether these translate into hazardous events in the far field, which is debatable."
When Fogo erupted last year, Ramalho and other geologists rushed in to observe. Lava flows (since calmed down) displaced some 1,200 people, and destroyed buildings including a new volcano visitors' center. "Right now, people in Cape Verde have a lot more to worry about, like rebuilding their livelihoods after the last eruption," said Ramalho. "But Fogo may collapse again one day, so we need to be vigilant."
The above post is reprinted from materials provided by The Earth Institute at Columbia University. Note: Materials may be edited for content and length.