Tuesday 10 July 2012

Earthquake in Nottinghamshire, England.

On Tuesday 5 July 2012, slightly before 10.30 pm GMT (slightly before 11.30 pm British Summertime), the British Geological Survey recorded an Earthquake in northern Nottinghamshire, centered roughly 2 km beneath the village of Edwinstowe (roughly 10 km northeast of Mansfield), and measuring 1.3 on the Richter Scale. Such a small quake is highly unlikely to have been felt, and certainly will not have caused any appreciable damage.

The location of the 5 July 2012 quake. BGS.

The cause of Earthquakes in the UK can be hard to determine, since they tend to be small and infrequent. The country is not close to any active tectonic margin, but is still subject to stresses from a number of sources. It is not usually possible to attribute a particular quake to any of these, and realistically most quakes are likely to have been caused by a combination of stresses from different sources. Firstly the country, along with the rest of Eurasia, is being pushed to the east by the expansion of the Atlantic Ocean. Europe is also being pushed to the north by the impact of Africa from the south; this causes frequent Earthquakes in the eastern Mediterranean, but the rest of Europe is not immune from the influence of this pushing. Then there are smaller areas of expansion under the North Sea, the Rhine Valley and the Bay of Biscay, all of which exert some pressure on the rocks of the UK. Finally their is glacial rebound; until about 10 000 years ago much of the north of the UK was covered by ice, which was often hundreds of meters thick. This pushed the rocks of the British lithosphere down into the underlying mantle. Now that this ice has gone these rocks are rebounding, at geological speeds, which leads to the occasional minor Earthquake.

As a rule of thumb the further north and west you go in Great Britain the more Earthquakes you will encounter. Nottinghamshire is not a particularly Earthquake-prone county even by British standards, though there have been several minor quakes in nearby South Yorkshire recently, which may indicated some sort of tectonic stress in the region.

Mansfield was shaken by a quake estimated at 4.2 on the Richter Scale in March 1816, and the county suffered a large quake in April 1180, though there is no means to estimate the size of this event.

Reports by witnesses who have felt quakes are useful to scientists studying tectonic events. If you felt this quake (or live close by but did not, which is also data) you can report it to the British Geological Survey here.

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