Second earthquake in a month rattles Irish Sea

27 Jun 2013

A map pinpointing the epicentre of the 2.8-magnitude earthquake on 26 June in the Irish Sea. Image via Dublin Institute for Advanced Studies

The second earthquake in a month has been recorded in the Irish Sea, measuring 2.8 on the Richter scale and followed by two aftershocks.

The aftershocks happened about 30 seconds and two minutes and 30 seconds, respectively, after the main event at 11.28pm on Wednesday, 26 June.

The Irish National Seismic Network (INSN), which monitors seismic activity in the region, said the earthquake occurred at a depth of 12km.

The epicentre was located about 2km off the coast off the Llŷn Peninsula in Wales and 97km southeast of Dublin, near where a 3.8-magnitude earthquake happened on 29 May.

“This earthquake, which would be considered relatively minor on the Richter scale, was located approximately 0.5km south of the magnitude 3.8 event which occurred last month,” said Dr Yochai Ben-Horin of the Dublin Institute for Advanced Studies (DIAS), which operates the INSN.

Ben-Horin said the recent earthquake was felt throughout North Wales, including Holyhead, Bangor, Menai Bridge, Blaenau Ffestiniog, Bodorgan, Pwllheli and Caernarfon.

“We have not yet received any felt reports from people living on Ireland’s east coast but the quake was recorded by our network of seismic stations throughout Ireland,” Ben-Horin said.


The seismic traces of the events regarding the 2.8-magnitude earthquake on 26 June in the Irish Sea. Image via Dublin Institute for Advanced Studies

Ben-Horin also explained there has been an increase in seismic activity in the area in recent months and further minor earthquakes are likely.

However, he added that there was no way to currently tell if a larger earthquake is likely to occur.

This latest rattler could represent the continuation of a natural cycle of seismic activity that began on 7 February, when a magnitude 2.3 earthquake struck the area, said Ben-Horin.

This was followed by the 29 May earthquake, and a series of smaller earthquakes a couple of days later.

“It is unclear whether stronger earthquakes are likely in the coming weeks but aftershocks can be expected in the hours and days ahead, although many will be too weak to be felt,” Ben-Horin said.

Anyone who felt yesterday’s earthquake may submit felt reports to DIAS online.

Tina Costanza was a journalist and sub-editor at Silicon Republic