2008 Lincolnshire Earthquake - Cause

Cause

The 2008 Lincolnshire earthquake was caused by the sudden rupture and motion along a strike-slip fault, 18.6 kilometres (12 mi) beneath Lincolnshire. 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. Computer calculations carried out by the BGS infer sinistral motion on a N–S or dextral motion on a 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. 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. The energy released was 3.98×1012 joules (equal to the detonation of ~950 tonnes of TNT).

Unlike typical earthquakes worldwide, the earthquakes of Northern Europe are intraplate earthquakes, meaning they are not close to tectonic plate boundaries. Most intraplate earthquakes in Northern Europe, including the UK, 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. Indeed, the motion on the strike-slip fault responsible for 2008 Lincolnshire earthquake is compatible with a local NW–SE stress field; 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.