1275 British earthquake

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1275 British earthquake
In the background, a square stone church tower atop a steep and narrow terraced hill. The foreground shows a concrete path leading upwards to the tower. People are hiking up the hill, and in the midground is sheep grazing on the terraces.
Glastonbury Tor (pictured in 2010) showing the tower of the rebuilt St Michael's Church (C14)
Local date11 September 1275 (1275-09-11)
Local timeMorning
Magnitude6 Mw (hypothesised)
Areas affectedLondon, Canterbury, Winchester, Glamorgan
Max. intensityMSK-64 VII (Very strong)
EMS-98 VIII (Heavily damaging)
ForeshocksNone reported
AftershocksNone reported
CasualtiesMultiple fatalities

On 11 September 1275, an earthquake struck the south of Great Britain. The epicentre is unknown, although it may have been in the Portsmouth/Chichester area on the south coast of England[1] or in Glamorgan, Wales.[2] The earthquake is known for causing the destruction of St Michael's Church on Glastonbury Tor in Somerset.

Earthquake

The annals of Waverley in Surrey report that the earthquake occurred "between the first hour of the day and the third" on 11 September 1275.[3] It was felt in London, Canterbury, Winchester and Wales, and may have been felt across the rest of England.[4] One account described how it was felt "chiefly in the west".[5] Neither foreshocks nor aftershocks are reported as having occurred.[6]

The earthquake caused the destruction of the 11th-century timber Church of St Michael atop

Walter de Hemingburgh observed that "there was a general earthquake in London and in the kingdom of England, both in camps and towns, habitations and fields".[8] It is possible that the coastal effects of the earthquake are better attributed to unrelated inclement weather, as the word "earthquake" may have archaically referred to thunder.[8]

The British Geological Survey hypothesises that the extent and spread of damage suggests an intensity of at least 7 on the Medvedev–Sponheuer–Karnik scale ("very strong"), or 8 on the European macroseismic scale ("heavily damaging").[9]

Epicentre

The

strike-slip fault.[11] This hypothesis is strengthened by the report of Thomas Wykes, who wrote that the shock was more intense on the south coast.[2]

A possible alternative epicentre is in South Wales. Edward Gamage, the rector in St Athan, Glamorgan, described an earthquake causing immense damage to Glamorgan and Somerset. Gamage, an antiquarian in the 18th century, wrote a history of the Strandling family of Bristol where he described the earthquake as occurring in the time of Sir John Strandling, which is probably the same as the 1275 event. This suggests an epicentre closer to Swansea and implies a magnitude of 6 Mw.[2]

Some sources[3][12][13] cite the earthquake as being a Cornish or French event, mistaking a reference to the destruction at "St Michael on the Mount" (the church on Glastonbury Tor) for occurring at St Michael's Mount or Mont-Saint-Michel.[9] The annals of Waverley refer to an earthquake affecting the whole country and destroying the church called "St Michael of [the] Mount", although no specific mention of the location of the church is made.[3]

References

  1. ^ a b c d "Notes on Individual Earthquakes". British Geological Survey. Archived from the original on 19 November 2007. Retrieved 5 August 2019.
  2. ^ a b c d e Musson, Roger (9 July 2015). "What Was the Largest British Earthquake?" (PDF). SECED Conference 2015: 3. Retrieved 5 August 2019.
  3. ^
    ISBN 9781447498544
    .
  4. ^
    doi:10.1046/j.1468-4004.2003.44114.x
    .
  5. ^ Proctor, Richard A (1884). Knowledge: An Illustrated Magazine of Science. p. 301. Retrieved 8 August 2019.
  6. JSTOR 30079058
    .
  7. ^ Crossley, John. "Glastonbury Tor, Somerset". www.uksouthwest.net. UK South West. Retrieved 9 August 2019.
  8. ^
    ISBN 9781118949955
    .
  9. ^ a b Musson, RMW (2008). "The seismicity of the British Isles to 1600" (PDF). British Geological Survey (Earth Hazards and Systems): 37. Retrieved 6 August 2019.
  10. ISBN 9780521140997
    .
  11. ^ West, Ian. "Earthquakes of the South of England – Geology Guide (new version)". University of Southampton. Retrieved 5 August 2019.
  12. ISBN 978-0-907018-58-2
    .
  13. ^ Historic England. "THE CHURCH OF SAINT MICHAEL, St. Michael's Mount (1310728)". National Heritage List for England. Retrieved 6 August 2019.
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