On Saturday 8 September 2012, slightly after 8 pm Irish Summertime (slightly after 7 pm GMT), the British Geological Survey recorded a Magnitude 1.1 km Earthquake 1.1 km beneath Lough Swilly, about 1 km southwest of Buncrana in County Donegal. An Earthquakes this small are highly unlikely to cause any damage or casualties, and quite often pass completely unnoticed, though this one was reportedly felt.
Map showing the location of the 8 September Earthquake. Google Maps.
Earthquakes are far less common in Ireland than Great Britain (geographical, not political definitions; London, Cardiff and Edinburgh are on the island of Great Britain, Dublin and Belfast on Ireland), but the Loch Swilly area is more prone to tremors than the rest of the country.
The precise cause of Earthquakes in Britain and Ireland can be hard to determine, and there are not obvious centers of geological activity close to the countries. Along with the rest of Europe they are being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Europe from the south. There are also lesser centers of expansion beneath the North Sea, the Rhine Valley and the Bay of Biscay, all of which exert some tectonic pressure, but these are all a long way from County Donegal. Finally there is glacial rebound; until about 10 000 years ago much of the north of Britain and Ireland were covered by thick ice, pushing the rocks of the Lithosphere down into the underlying Mantle. Now this ice is gone and the rocks are slowly rebounding, causing the occasional Earthquake as they do so.
See also Earthquake off the coast of County Mayo, Ireland and Earthquakes on Sciency Thoughts YouTube.
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