Northern Ireland

Irish Sea quake aftershocks 'felt for days'

Irish Sea
Image caption The earthquakes struck in the Irish Sea on Sunday

Aftershocks from two earthquakes that struck in the Irish Sea may be felt for days to come, it has been claimed.

The strongest quake, at a depth of 5km, was recorded by the British Geological Survey at 10:00 BST on Sunday and the smaller was recorded at 05:30 BST.

The larger earthquake was also recorded by seismometers in Donegal and Wexford.

The Irish National Seismic Network said the quakes were probably caused by stresses from the weight of glaciers covering land during the Ice Age.

Director Tom Blake said it was unusual that the earthquakes - measuring 2.4 and then a stronger 3.3 on the Richter scale - happened in the Irish Sea.

"It is impossible to tell if stronger earthquakes will occur in the coming days and weeks, but aftershocks can be expected even if most, if not all, will be too weak to be felt," Mr Blake said.

Social media users took to Twitter saying they felt the ground move beneath them - particularly in the north west of England.

Ice sheets

Mr Blake, from the School of Cosmic Physics in the Dublin Institute for Advanced Studies, said their cause was probably no different from other earthquakes in Britain and Ireland.

"Although Britain and Ireland are far from any plate boundaries, much of the region is still experiencing quakes due to the removal of the weight of ice sheets that once covered the land," he said.

"Occasionally this post-glacial isostatic rebound - the phenomenon of the land surface gradually returning to its pre-glacial contours - results in earthquakes of this magnitude, particularly in the northern half of the islands."

A slightly larger earthquake was recorded in the Irish Sea in May, which was felt in parts of Ireland and North Wales.

The 3.8 magnitude tremor occurred 15km from Abersoch in Gwynedd, Wales.

People as far away as Dublin, Wexford, Wicklow and Kildare claimed they felt it at the time.

According to the Irish National Seismic Network, the largest known British earthquake struck near the Dogger Bank in the North Sea off the east coast of England in 1931, with a magnitude of 6.1.

The largest to impact Ireland occurred on the Llyn peninsula, North Wales, in July 1984.

The 5.4 magnitude earthquake was the largest ever recorded earthquake on mainland Britain and was felt throughout Ireland's east coast, Wales and England.