On Sunday 30 December 2012, slightly before 3.00 pm GMT, the British Geological Survey recorded a Magnitude 1.3 Earthquake 7 km beneath the Somerset town of Highbridge, roughly 15 km south of Weston-super-Mare. This is far too small a quake to have caused any damage at the surface, and may not have even been felt.
The location of the 30 December Earthquake. Google Maps.
The cause of Earthquakes in the British Isles is often hard to determine, since there is no one simple explanation for most of them, most being the result of a combination of several different tectonic pressures. The UK is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. In addition there are lesser centers of geological expansion beneath the North Sea, the Rhine Valley and the Bay of Biscay, all of which exert some pressure on British Rocks. Finally there is glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice, which pushed the rocks of the lithosphere down into the underlying mantle. This ice is now gone and the rocks are slowly rebounding, causing the occasional Earthquake in the process - though this is more of an issue in the north of the country, particularly on the west coast of Scotland, the most quake-prone part of the country.
Witness reports can help geologists to understand the processes going on in Earthquakes. If you felt this quake, or were in the area but did not, which is also useful information, then you can report it to the British Geological Survey here.
See also Earthquake in Herefordshire, Earthquake in West Sussex, England, Earthquake off the Dorset Coast, Earthquake in Carmarthenshire and Earthquakes on Sciency Thoughts YouTube.
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