Tsunamis affecting the British Isles

Tsunamis affecting the British Isles are extremely uncommon, and there have only been two confirmed cases in recorded history. Meteotsunamis (displacements due to atmospheric pressure, rather than seismic shock) are somewhat more common, especially on the southern coasts of England around the English and Bristol Channels.[1][2]

Confirmed tsunamis

Scotland (6100 BC)
Main article: Storegga Slide

The east coast of Scotland was struck by a 21 m (70 ft) high tsunami around 6100 BC, during the Mesolithic period. The wave was caused by the massive underwater Storegga slide off Norway. 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 layer of deposited sand about 0.6 metres (2 ft) thick.

At the time, what became the east coast of England was connected to the areas of 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 at the time.[3][4] Much of this land would have been inundated by the tsunami, with a catastrophic impact on the local human population.[5]

Lisbon earthquake (1755)

The coast of Cornwall was hit by a 3 m (10 ft) 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. The tsunami was also observed along the south coast of England and on the River Thames in London.[6] 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 6 feet (1.8 m) very rapidly, then ebbed equally rapidly. The sea rose 8 feet (2.4 m) in Penzance and 10 feet (3.0 m) 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".[7]

The tsunami also reached Galway in Ireland, at a height of 2 m (6.6 ft), and caused some serious damage to the "Spanish Arch" section of the city wall.

Lisbon earthquake (1761)

At Mount's Bay in Cornwall, a small tsunami up to 1.9 meters was observed following the 1761 Portugal earthquake.[8]

Meteotsunami (1929)
See also: Meteotsunami

On 20 July 1929 a wave reported as being between 3.5 and 6 m (11 and 20 ft) high struck the south coast of England including busy tourist beaches at Worthing, Brighton, Hastings and Folkestone. Two people drowned and the wave was attributed to a squall line travelling along the English Channel.[9][10]

South coast (2011)

A small tsunami in the English Channel with a peak wave height anomaly of 40 cm (16 in) occurred on 29 June 2011 affecting four counties on the south coast of England; Cornwall, Devon, Dorset and Hampshire. The tsunami was described as mild and there were no records of injuries or damage. Video footage clearly showed the tsunami and there were reports of fish leaping out the water and hair lifting up because of a static charge.[11] 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.[9]

Possible tsunamis

Orkney and Shetland (3500 BC)

Traces of a tsunami called the Garth tsunami have been reported from the Shetland Islands.[12] The tsunami took place 5,500 years ago and may be connected to the presence of mass burials on both the Shetland and Orkney islands.[13]

England and Wales (1014)

A widespread flood was reported in the Anglo-Saxon Chronicle to have occurred in Britain, from the coast of Cumbria to Kent, on 28 September 1014. William of Malmesbury stated that "A tidal wave... grew to an astonishing size such as the memory of man cannot parallel, so as to submerge villages many miles inland and overwhelm and drown their inhabitants." The event was also mentioned in Welsh bardic chronicles. Accounts suggest that a flood affected Kent, Sussex, Hampshire, Cumbria, and Mount's Bay in Cornwall, where the Bay was "inundated by a ‘mickle seaflood’ when many towns and people were drowned".[14]

Dover Straits earthquake (1580)
Main article: 1580 Dover Straits earthquake

On 6 April 1580 there was a 5.8 magnitude earthquake with its epicentre on the sea bed close to Calais. Giant waves were reported, and hundreds of people were killed when ships were sunk by the waves and the low-lying coastal land around Calais was inundated by the sea. In Dover, part of the chalk cliff collapsed, taking with it part of Dover Castle. A contemporary French account states: "in the city of Calais such a horrible and terrible earthquake came to pass that a great part of the houses fell, and even the sea overflowed into the city and did ruin and drown a great number of houses, and numerous persons perished, and a great multitude of beasts lost which were at pasture outside this city." In recent years, it has been suggested that these waves were a tsunami and not seiches. It is unlikely that the earthquake alone was strong enough to rupture the sea bed to trigger a tsunami, but it appears to have been sufficiently powerful to have caused an undersea landslide that was capable of generating a tsunami, as happened in Papua New Guinea in 1998, killing around 2,500 people.

Bristol Channel (1607)
Main article: Bristol Channel floods, 1607

The Bristol Channel floods are attributed to a storm surge, but some have suggested that it was a tsunami caused by an earthquake or a landslide from the Irish coast.

North Sea (1858)

A tsunami was reported by witnesses in England, Germany, the Netherlands and Denmark on 5 June 1858.[15] A witness stated that at 09:15, the sea in Pegwell Bay, East Kent, "suddenly receded about 200 yards (180 m) and returned to its former position within the space of about 20 minutes".[16] The Times reported severe thunderstorms and flooding in the west of England on the same day. Due to the weather conditions, it may have been a meteotsunami.

Future tsunamis

In the 1990s, geologists realised that the Cumbre Vieja volcano in La Palma, in the Canary Islands off North Africa, could pose a tsunami risk to Britain and Ireland, 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, the southern and western parts of Ireland and the south coast of England. It is estimated that the waves will take around 6 hours to reach the British Isles, and that when they do they will be around 10 metres (30 ft) high.[17] Britain would be badly hit, and it is believed by some that if nothing is done, thousands of lives will be lost. There is considerable controversy about the accuracy of these predictions. Researchers at Delft University of Technology in the Netherlands 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.[18]

See also

Notes

Citations
  1. Haslett, Simon K; Mellor, Holly E.; Bryant, Edward A. (2009). "Meteo-tsunami hazard associated with summer thunderstorms in the United Kingdom". Physics and Chemistry of the Earth, Parts A/B/C. 43 (17–18): 1016–1022. Bibcode:2009PCE....34.1016H. doi:10.1016/j.pce.2009.10.005.
  2. Haslett, Simon K; Bryant, Edward A. (2009). "Meteorological Tsunamis in Southern Britain: an Historical Review". The Geographical Review. 99 (2): 146–163. doi:10.1111/j.1931-0846.2009.tb00424.x. S2CID 162412431.
  3. Patterson, W, "Coastal Catastrophe" (paleoclimate research document), University of Saskatchewan Archived 9 April 2008 at the Wayback Machine
  4. Vincent Gaffney, "Global Warming and the Lost European Country" Archived 10 March 2012 at the Wayback Machine
  5. Bernhard Weninger et al., The catastrophic final flooding of Doggerland by the Storegga Slide tsunami, Documenta Praehistorica XXXV, 2008 Archived 11 October 2010 at the Wayback Machine
  6. Britain), Royal Society (Great; Hutton, Charles; Shaw, George; Pearson, Richard (1755). "An extraordinary and Surprising Agitation of the Waters, though without any perceptible Motion of the Earth, having been observed in various Parts of this Island, both Maritime and Inland, on the same Day, and chiefly about the Time that the more Violent Commotions of both Earth and Waters so extensively affected many very distant Parts of the Globe; the following Accounts, relating to the former, were transmitted to the Society; in which are specified the Times and Places when and where they happened". Philosophical Transactions of the Royal Society. XLIX: 351–398. Bibcode:1755RSPT...49..351R. doi:10.1098/rstl.1755.0059. Retrieved 5 July 2011.
  7. Boscowitz, Arnold (1890). Earthquakes. Routledge. p. 192.
  8. M. A. Baptista, J. M. Miranda, and J. F. Luis (2006). "In Search of the 31 March 1761 Earthquake and Tsunami Source". Bulletin of the Seismological Society of America. 96 (2): 713–721. Bibcode:2006BuSSA..96..713B. CiteSeerX 10.1.1.845.1005. doi:10.1785/0120050111.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. "Meteotsunami | South West England | June 2011 | British Geological Survey (BGS)". bgs.ac.uk. 2011. Retrieved 8 July 2011.
  10. "Worthing History". hadesign.co.uk.
  11. "BBC News – Underwater landslide likely cause of 'mild tsunami'". bbc.co.uk. 29 June 2011. Retrieved 30 June 2011.
  12. Bondevik, Stein; Mangerud, Jan; Dawson, Sue; Dawson, Alastair; Lohne, Øystein (1 August 2005). "Evidence for three North Sea tsunamis at the Shetland Islands between 8000 and 1500 years ago". Quaternary Science Reviews. 24 (14): 1757–1775. Bibcode:2005QSRv...24.1757B. doi:10.1016/j.quascirev.2004.10.018. hdl:1956/735. ISSN 0277-3791.
  13. Cain, Genevieve; Goff, James; McFadgen, Bruce (1 June 2019). "Prehistoric Coastal Mass Burials: Did Death Come in Waves?". Journal of Archaeological Method and Theory. 26 (2): 714–754. doi:10.1007/s10816-018-9386-y. ISSN 1573-7764.
  14. "Tsunamis affecting the British Coast – Slide Show".
  15. Stampf, Olaf, "Scientists Say North Sea Is Vulnerable to Tsunamis", Der Spiegel (English edition), 14 April 2012
  16. "Violent Thunder Storms", The Times, 7 June 1858, p.9
  17. Lean, Geoffrey (2 January 2005). "Britain could be hit by 30ft wave, says top scientist – Environment – The Independent". The Independent. London: INM. ISSN 0951-9467. OCLC 185201487. Archived from the original on 4 February 2010. Retrieved 8 July 2011.
  18. "New research puts 'killer La Palma tsunami' at distant future". physorg.com. 20 September 2006. Retrieved 18 October 2008.

References
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