Friday 22 March 2013

Earthquake in Cumbria.

On Friday 21 March 2013, slightly before 4.15 am, the British Geological Survey recorded a Magnitude 1.2 Earthquake at a depth of 3 km between Lake Ulswater and Haweswater Reservoir. This is a small quake, and given its remote location and the time of day at which it occurred, is unlikely to have been felt by anyone, much less have caused any damage.

The location of the 21 March Earthquake. Google Maps.

The cause of Earthquakes in the UK can be hard to determine; since there is no single overriding cause of tectonic stress in Britain, it is likely that most quakes are the result of the interplay of more than one source of stress.

The UK is being pushed to the east by the expansion of the Atlantic Ocean (along with the rest of Eurasia) and to the north by the impact of Africa into Europe from the south. It is also affected by lesser spreading areas beneath the North Sea, the Rhine Valley and the Bay of Biscay. Finally there is glacial rebound; until about 10 000 years ago much of Britain was covered by a thick layer of glacial ice, pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing back into their original position, causing the occasional Earthquake in the process. This is particularly true in the northwest of the country, where the thickest Pleistocene glaciers are thought to have occurred, with the west coast of Scotland being the most Earthquake-prone part of the country.

Scientists can use witness records of Earthquakes to help them understand these events and the geological processes that cause them. If you felt this quake (or if you were nearby but didn't, which is also useful information) then you can report it to the British Geological Survey here

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