© BBC
The Irish National Seismic Network (INSN) said the quakes, which occurred this morning off the north west coast of England, were probably caused by stresses built up from the weight of glaciers covering land during the Ice Age.
INSN 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.
No injuries have been reported. Social media users took to Twitter saying they felt the ground move beneath them, particularly in the north west of England. Blackpool resident Cathy Welsh told the BBC, "I looked round and the bed was shaking. I thought it was a big lorry going past."
A slightly larger earthquake was recorded in the Irish Sea back in May, which was felt in parts of Ireland and north Wales.
The 3.8 magnitude tremor occurred 15km away from Abersoch in Gwynedd, Wales. People as far away as Dublin, Wexford, Wicklow and Kildare claimed they felt it at the time.
True, the land and subsea in the NW of the British Isles has been rising for centuries as a result of glacial rebound. In Workington, West Cumbria Mooring Bollards were still present a few years ago maybe a half mile or so inland from the current docks where ships moored perhaps a century or more ago on what is now dry land. Similarly the SE of England is sinking so that Godwyn's Island became the Goodwin Sands a few centruies ago. The Earthquakes here are typically quite small but do cause some damage from time to time. Strangely enough we also have the largest density of tornados anywhere in the world, but they too are small rarely causing much damage.