The British Geological Society reported that the earthquake had also been felt in Liverpool, Mold, Cardigan, and Wicklow, Ireland.
– British Geological Survey
This was a larger than average earthquake, we get around one a year of this size.
People have reported hearing an initial loud banging, followed by rumbling, and intense shaking.
An earthquake close to North Wales has been felt over an area of 140km by people who reported "intense shaking".
The epicentre of the earthquake in the Irish Sea was 15km away from the town of Abersoch, Gwynedd, and measured a magnitude of 3.8, the British Geological Survey (BGS) said.
It happened at around 4.15am and was felt as far away as Southport in Merseyside.
More than 100 reports from people who felt the earthquake have been made to the BGS, who said the majority were within a 100km radius.
Just felt a Earthquake anyone else feel it ?
Wow! Anyone else feel an earth tremor a few minutes ago, or was it just in Gwynedd?
Looks like earthquake tremor felt in Anglesey, Bangor, Blanaeu Ffestiniog so quite widespread.
The British Geological Survey has confirmed there was an earthquake with an estimated magnitude of 3.8 off the Llyn Peninsula this morning. It was detected at around 4.15am and people have reported feeling the tremor as far afield as Rhyl.
A 3.8 magnitude earthquake has hit Llyn Peninsula in north Wales, the British Geological Survey reports.
The quake hit at a depth of eight kilometres.