The earthquake was caused by the sudden rupture and motion along a strike-slip fault, 18.6 kilometres (12 mi) beneath Lincolnshire.[1] Earthquake motion occurred over a time span of ~2 minutes but it was most intense and was felt at the surface for just 10 to 30 seconds; maximum vertical ground motion at the epicentre of the earthquake was only ~1 mm. The observed focal mechanism implies either sinistral motion on a N–S or dextral motion on an E–W oriented strike-slip fault. The nine aftershocks observed, ~5 kilometres (3 mi) SSW of the main earthquake event, point to an approximately N–S oriented fault.[1] From the 5.2 ML magnitude of the main earthquake, a motion of a few centimetres along a ~2.5 kilometres (2 mi) long fault rupture is derived.[4] The energy released was 3.98×1012joules (equal to the detonation of ~950 tonnes of TNT).[5]
Unlike typical earthquakes worldwide, the earthquakes of Northern Europe are intraplate earthquakes, meaning they are not close to tectonic plate boundaries.[6] Most intraplate earthquakes in northern Europe, including the British Isles, are thought to be driven by distant tectonic stresses – a combination of E–W North Atlantic Ridge and N–S African plate regional stress fields, and local mantle conditions.[7][8] Indeed, the motion on the strike-slip fault responsible for the earthquake is compatible with a local NW–SE stress field;[1] a product of the E–W and N–S regional stress fields.
Only a minority of earthquakes in the UK are related to post-glacial rebound e.g. the minor earthquakes (<3.5 ML) of western Scotland, where glaciers ~1 km thick existed during the peak of the last ice age.[8]
Effects
The spire of St Andrew's church in Haconby was damaged
The earthquake resulted in structural damage to many homes and businesses in the epicentral area.[1][3] Buildings as large as apartment blocks were reported to have shaken for up to 30 seconds afterwards.[2] Birds and pets became highly agitated.[9] There were no deaths, but a 19-year-old man in Wombwell, Barnsley, South Yorkshire suffered a broken pelvis when a piece of chimney fell through the roof onto his attic bed.[3][10] The earthquake was felt by people as far south as Bournemouth, where it was felt as a mild but noticeable vibration, and as far away as Bangor, Northern Ireland, where it woke people.[3][9]
Police in the Midlands received more than 5,000 telephone calls in an hour from members of the public regarding the earthquake.[2] The earthquake caused power cuts in some areas.[2] A church in March, Cambridgeshire reported that, since the earthquake, water had been coming up from the ground into the cellar at a rate of 10 imperial gallons (45 L) per hour.[11] The spire of St Mary Magdalene church at Waltham on the Wolds in Leicestershire was damaged and was to be rebuilt at a cost of £100,000.[12] Also damaged were the spires of St Andrew's church in Haconby, St Andrew's of Witham on the Hill, St Vincent's church in Caythorpe,[13] all three in South Kesteven.
The cost of insurance payouts was estimated to be around £30 million,[14] with the majority of damage being done to chimneys, roof tiles and by falling masonry.[14]
A total of nine aftershocks were recorded. The largest, measuring 2.8 on the Richter scale, occurred around five weeks after the initial event, on 5 April at 13:57 GMT.[18]
Responses
Firefighting crews were called out to 50 incidents and 1 fire as a result of the quake.[19] Building Control & Street Force officers worked quickly to assess damage in the area around West Lindsey,[20] and West Lindsey District Council also urged people to call their telephone number if people were concerned about damage to their homes.[20] Trent Street in Gainsborough was closed to traffic whilst a local builder assessed if properties were structurally safe,[20] after 1 family was evacuated from their house following concerns about collapses.[20]
Significance
The BGS described the earthquake as an "extremely large earthquake in UK terms but not large in world terms".[2] Approximately 200 earthquakes occur in the UK every year, approximately 175 of which are too weak to be noticed by humans.[1]
See also
Seismicity in the United Kingdom from 1990 to 27 February 2008
^Cloetingh, S.; Ziegler, P. A.; Beekman, F.; Andriessen, P. A. M.; Matenco, L.; Bada, G.; Garcia-Castellanos, D.; Hardebol, N.; Dezes, P.; Sokoutis, D. (2005). "Lithospheric memory, state of stress and rheology: neotectonic controls on Europe's intraplate continental topography". Quaternary Science Reviews. 24 (3–4): 241–304. Bibcode:2005QSRv...24..241C. doi:10.1016/j.quascirev.2004.06.015.
^ abKossof, Julian (27 February 2008). "Earthquake hits UK". The Daily Telegraph. Archived from the original on 3 March 2008. Retrieved 27 February 2008.
^"Alerte Sismique" (in French). Commissariat à L'Energie Atomique (CEA). 27 February 2008. Archived from the original on 2 March 2008. Retrieved 27 February 2008.
