Llyn peninsula hit by earthquake of 3.8 magnitude
A small earthquake measuring 3.8 in magnitude hit north Wales in the early hours of Wednesday morning.
The tremor centred on the Llyn peninsula in Gwynedd.
The British Geological Survey (BGS) said the centre point was between the seaside towns of Aberdaron and Nefyn.
People living as far away as Southport, Merseyside, the Isle of Man and Dublin, the Irish capital, reported "intense shaking" at 04:16 BST, but there were no reports of damage or injury.
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.
Dr Brian Baptie, head of seismology at the BGS, said the size of the tremor was not unusual for the UK.
"We get an earthquake of this size in the UK maybe once or twice every couple of years," he told BBC Radio Wales.
"We also know that north Wales is one of the more seismically active parts of the UK. It's got a long history of earthquakes over the past few hundred years."
Dr Baptie said the rumblings that residents felt were consistent with an earthquake of this size.
He added: "It might be felt up to a few hundred kilometres away, people could feel the house shake, they could hear audible phenomena like rumbling, and maybe objects would rattle."
Mari Roberts from Morfa Nefyn, near Pwllheli, recorded the sound generated by the tremor on her smart phone.
"The app I have on my phone recorded it and it just automatically switches on to record when there's any noise. I thought it wouldn't be loud enough to record on the phone but it actually did and it sounds frightening when you listen back to it," she said.
Graham Williams, of Pentir, near Bangor, told BBC Radio Wales: "I woke up to a cracking sound and realised the house was shaking.
"I could hear a low rumble for about 15 seconds and then it stopped."
Kevin Clark, of Llynfais, Anglesey, said the tremor came as a bit of a shock.
"I was fast asleep this morning and it sounded like a train running around the outside of the house," he said.
"And considering in Anglesey where we are there's no train, it was a bit of a shock, and the whole place was shaking and rumbling, like a deep rumbling sound."
He added that his 14-year-old daughter woke up to find her chandelier-style light shaking violently.
North Wales was also hit by a smaller earthquake in Caernarfon in February, of 2.3 magnitude.
The latest tremor is just a few miles from the point on the Llyn peninsula where an earthquake struck in July 1984 with a magnitude of 5.4.
It was the most powerful recorded in mainland Britain in the past 200 years.
Dr Baptie said there was no evidence to suggest the number of earthquakes was increasing.
"All of the data we've collected over the last 30 or 40 years, and historical data going back hundreds of years, doesn't bear that out at all," he added.