Strong tremor hits Wales: Initially reported at 4.3 magnitude, but was it really an earthquake?

BBC
Wed, 29 May 2013 04:03 UTC

A small earthquake measuring 3.8 in magnitude has 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 in Merseyside, Dublin in Ireland and on the Isle of Man 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 silently active parts of the UK. It's got a long history of earthquakes over the past few hundred years."

Dr Baptie said the rumblings residents felt was 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."

Graham Williams from 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 measuring 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 last 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.

Comment: This 'quake' was reported by the European-Mediterranean Seismological Centre to have been magnitude 4.3.

The following eyewitness report has some interesting additional information:

"People have reported hearing an initial loud banging, followed by rumbling and intense shaking."

And here:

Peter Wilkinson, owner of the Penrallt Coastal Campsite, about a mile from the epicentre, said he was woken by what felt like a thud and thought that the corner of his house had fallen off. [...]

"I got up to see if something had fallen over in the room and went to check all of the rooms, but there wasn't any sign.

I would describe it as like hearing a large thud - like a wardrobe falling over."

Loud bangs followed by rumbling suggests that it might have been another overhead cometary explosion. In addition, the sound can often seem very close because of the electrophonic nature of meteors. Objects that are close by will transduce the meteor shockwave into an audible sound.

There was another fireball significant event over the UK and Ireland just five days previously, and it does appear to be raining fireballs the world over...