Tsunamis in the United Kingdom

Tsunamis are considered rare in the United Kingdom, which has been affected by only one known tsunami caused by an underwater earthquake, and one by an underwater landslide. However meteotsunamis are somewhat more common, especially on the southern coasts of England around the English and Bristol Channels.
6100 BC Scotland tsunami
The east coast of Scotland was struck by a high tsunami around 6100 BC, during the Mesolithic period. The wave was caused by the massive underwater Storegga slide off Norway, which dates from around the same time. The tsunami even washed over some of the Shetland Islands. Tsunamite (the deposits left by a tsunami) dating from this event can be found at various locations around the coastal areas of Scotland, and are also a tourist feature in the Montrose Basin, where there is a thick layer of deposited sand about thick.
At the time, what became the east coast of England was connected to the areas of modern Denmark and the Netherlands by a low-lying land bridge, now known to archaeologists as Doggerland. The area is believed to have had a coastline of lagoons, marshes, mudflats, and beaches, and may have been the richest hunting, fowling and fishing ground in Europe then available. Much of this land would have been inundated by the tsunami, with a catastrophic impact on the local human population.
Bristol Channel, 1607
The Bristol Channel floods, which happened on the morning of January 30, 1607 (New style) , are suggested to be a tsunami either caused by an earthquake, a landslide from the Irish coast or a freak combination of high tides and a storm surge. There is historical evidence suggesting a tsunami, such eyewitness accounts describe a wave as "mighty hilles of water" - with sparks - and a wave that travelled so fast that not even a greyhound could escape it. These are clear descriptions of a tsunami. There is an ancient, large faultline off the Southern Western tip of Ireland, which scientists say could have possibly have triggered a tsunami in the Irish Sea. The continental shelf of Ireland is also very steep, with a drop of about 100 metres, and scientists believe the 1607 tsunami might have been triggered by a landslide here, if not an earthquake. Scientists and geologists say that after studying the disaster they are more convinced that it was a tsunami, rather than a simple storm surge.
1755 Lisbon earthquake
The coast of Cornwall was hit by a three metre high tsunami on 1 November 1755, at around 14:00. The waves were caused by the 1755 Lisbon earthquake. The tsunami took almost four hours to reach the UK, and by the time the waves reached Cornwall they had lost most of their destructive power. The tsunami was also observed along the south coast of England and on the River Thames in London. Contemporary reports say that there were three of these tsunami waves, and that the sea receded very quickly, then rose up. At St Michael's Mount, the sea rose suddenly and then retired; ten minutes later, it rose very rapidly, then ebbed equally rapidly. The sea rose in Penzance and at Newlyn; the same effect was reported at St Ives and Hayle. Although there is no record of the overall death toll, the 19th century French writer, Arnold Boscowitz, claimed that "great loss of life and property occurred upon the coasts of Cornwall".
The tsunami also reached the city of Galway in Ireland, at a height of two metres, and caused some serious damage to the "Spanish Arch" section of the city wall.
1929 Meteotsunami
On 20 July 1929 a wave reported as being between 3.5 and 6 metres high struck the south coast including busy tourist beaches at Brighton, Hastings and Folkestone. Two people drowned and the wave was attributed to a squall line travelling along the English Channel. Initial media speculation attributed the event to an underwater landslide, as no earthquakes were recorded at the time. However the British Geological Survey concluded that it was unlikely to have been caused by a submarine landslide and was probably a meteotsunami.
Possible future tsunamis
Geologists have described potential future tsunami threats to Britain from two different causes. In the 1990s, they realised that the Cumbre Vieja volcano in La Palma, in North Africa in the Canary Islands could pose a tsunami risk to Britain, as it is seemingly unstable. They concluded that a future volcanic eruption will result in the mass of rock alongside the volcanoes breaking off and falling into the sea as a massive landslide. This in turn will generate a huge tsunami, which will surge into the Atlantic Ocean and hit Spain, Portugal, the east coast of the United States, France, and the south coast of England. It is estimated that the waves will take around 6 hours to reach England, and that when they do they will be around 10 metres (30 ft) high. Britain would be badly hit, and it is believed by some that if nothing is done, thousands of lives will be lost. However, there is considerable controversy about the accuracy of these predictions. Researchers at the Dutch Technical University at Delft found the island to be much more stable than was widely believed, estimating that it would take at least another 10,000 years for the island to grow enough for there to be a danger.
Another tsunami geologists believe will hit Britain would be caused by a huge earthquake on a fault off the coast of Portugal; the same fault that caused the massive 1755 Lisbon earthquake (see above). Strain has been accumulating on that fault, which will eventually result in the fault breaking again, creating another megathrust earthquake, which could be as big as the 1755 earthquake (which was an estimated magnitude 9). When the earthquake happens, the south coast of England will definitely be affected by a tsunami, as it was in 1755. It will take around 4 hours for the tsunami to reach Cornwall, which should be enough time to issue a warning.

Main Menu

See Also

Main Menu