THE IRISH NATIONAL Seismic Network (INSN) has warned that further earth tremors are likely in the coming days in the Irish Sea and in North Wales, after a magnitude 3.8 earthquake struck this morning.

The earthquake was felt on the east coast of Ireland, and INSN Director Tom Blake said it occurred 97 km southeast of Dublin.

The British Geological Survey told TheJournal.ie that the epicentre was about 13km northwest of Abersoch in Gwynedd in Wales.

Pic: British Geological Survey

According to the INSN, the quake was measured at a depth of 8km and was followed four minutes later by a smaller 1.7 magnitude tremor at a shallower depth of 3km.

Moderate shaking was felt by residents of the town of Pwllheli on the Llŷn peninsula, while felt reports were also received from Caernarfon, Abersoch, Bangor, Holyhead, Southport, the Isle of Man and in south-eastern counties of Ireland. INSN seismic stations as far away as Valentia, Donegal and Galway recorded the earthquake.

The location is approximately 15km west of where a magnitude 5.4 earthquake occurred on the Llŷn peninsula on 19 July 1984, which was the largest ever recorded earthquake on mainland Britain.

When it struck it was felt throughout Ireland’s east coast, Wales and England, said INSN, with aftershocks measuring up to 4.3 on the Richter scale and some structural damage experienced on the Irish east coast.

Measuring the force of the earthquake. Image: Dublin Institute for Advanced Studies

Increase

Blake, who is from the School of Cosmic Physics in the Dublin Institute for Advanced Studies (DIAS), said there has been "a significant increase in seismic activity in the area in recent months", and that further minor earthquakes are likely.

But he said that today’s earthquake "was moderate enough to have relieved any pressure built up in the region and that it was unlikely to be a precursor to a stronger earthquake".

Blake added:

A 2.3 magnitude earthquake struck this very same area on 7 February and since then there have been a number of other tremors building up to this morning’s event. In fact, the past two months have seen a concentration of tremor activity right down the west coast of Britain with the most recent (2.9 magnitude) tremor occurring in Acharacle, Highland (Scotland) on May 18.

Although it is unlikely that the magnitude of today’s earthquake will be exceeded in the Irish Sea in the coming days, Blake said that aftershocks can be expected in the hours and days ahead, "although many will be too weak to be felt".

People in Ireland or Wales who may have felt this morning’s earthquake are invited to submit felt reports online at www.dias.ie.

Irish earthquakes

• A magnitude 2.7 earthquake was recorded off the northwest coast of Ireland on November 21 2012.
• On June 6 2012, a magnitude 4.0 earthquake was recorded off the coast of County Mayo, 60km west of Aughleam near Belmullet.
• The most significant land tremor in Ireland in recent years was a 2.7 quake that hit Lisdoonvarna in County Clare in May 2010.
• Earthquakes the size of today's quake occur every 18 months in the UK.

Read: Did you feel the earth move at 4.16am? (Seriously)>