Wednesday, 17 October 2012

Earthquake southeast of Jersey in the Channel Islands.

On Saturday 13 October 2012, slightly before 4.25 am, British Summertime (slightly before 3.25 am, GMT), the British Geological Survey recorded a Magnitude 1.4 Earthquake at a depth of 5 km, roughly  10 km southeast of Jersey in the Channel Islands. An Earthquake this small, this deep and this far offshore presents no threat to life or property, and is highly unlikely to have been felt onshore.

The location of the 13 October Earthquake. Google Maps.

The precise cause of Earthquakes in the English Channel can be hard to be determine, since they are usually the result of the combination of a number of different tectonic stresses. The Channel is, along with the rest of Eurasia, 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. There are also lesser areas of expansion beneath the North Sea, the Rhine Valley and the Bay of Biscay, all of which exert tectonic stress in the Channel region. Finally there is glacial rebound; until about 10 000 years ago much of northern Europe, including the north of the UK and upland areas of France, was covered by a thick layer of glacial ice. This pushed the rocks of the lithosphere down into the underlying mantle. This ice is now gone and these rocks are rebounding, albeit at geological speeds, causing the occasional Earthquake in the process.

Witness accounts of Earthquakes can be useful to geologists trying to understand the processes that cause them and the rocks beneath the surface. If you felt this quake (or if you were in the area but did not feel the quake, which is also useful information) then you can report it to the British Geological Survey here.


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