Media playback is unsupported on your device Media caption The BBC's Hwyel Griffith says one person who felt the tremors likened them to an "airplane coming in to land"

An earthquake has been recorded under the Bristol Channel, the British Geological Survey (BGS) has confirmed.

The 4.1 magnitude quake happened at about 13:21 GMT and was felt in Devon, south Wales and Somerset.

The focus was north of Ilfracombe, Devon, and south of the Gower, in Wales, and was at a depth of 3.1 miles (5km).

Devon and Cornwall Police said one caller in North Devon described it as "quite a violent tremor".

The BGS said it had received reports of people feeling the quake in Dartmoor, Bristol, Taunton, Swansea, Llanelli, Exmouth, Barnstaple, Gloucester and South Molton.

'Ran outside'

Susanne Sargeant, from the BGS, said it was "not unusual" to get quakes in the channel.

Image caption The quake was felt in parts of south Wales, Devon and Somerset

"It is an area in the Bristol Channel we know to have seismological action," she said.

"One guy called and said he was in his house when he felt the earthquake - he said it was a bit of a surprise. Things were shaking on the shelves and he ran outside.

"We do see earthquakes here from time to time and the last one was at Hartland Point in 2001 - that's 50km south west of today's earthquake."

Analysis We rarely think of Britain as vulnerable to earthquakes but its geology is surprisingly volatile. Today's quake of 4.1 is not all that unusual. According to the British Geological Survey, quakes of magnitude 4 are felt roughly every two years. Stronger tremors of magnitude 5 strike every 10-20 years. The worst on record was one of 6.1 in the Dogger Bank area of the North Sea in 1931. Explanations are often hard to come by. Britain's geological history has not left it with neat divisions between tectonic plates. Instead, the underground patterns of the rocks are highly complex with numerous minor faults, many under strain as parts of the country rise slowly in the aftermath of the last Ice Age. To put today's quake in context, it is one of nine around the world in the last 24 hours to reach a magnitude greater than 4, a reminder that for many regions earthquakes are a dangerous threat not a curious surprise.

Colin Taylor, who is a professor of earthquake engineering at the University of Bristol, said an event with a magnitude of 4.1 should not cause any significant damage.

"Humans are very sensitive to movement and although it might feel quite noticeable the worse you're likely to get is perhaps cracks in plaster or old masonry," he said.

"These so-called shallow events happen every now and again in the UK and is typically caused by a local fault - under stress - which moves from time to time.

"It is an intra-plate event rather than the inter-plate movement you'd see on something like the San Andreas fault in California."

Rachel Howells, 36, from West Cross in Swansea, said she was sat at her desk working when the building "shook like jelly" and it felt like something had "slammed into the side of the house".

"We are having an extension built on the side of the house and I just thought something had gone wrong with the building work.

"It didn't shake for long, it was more like a hiccup, just this big wobble.

"It didn't make any noise, it was like a shock, just the whole house reverberating, like a van going into the side of the house or something.

"It lasted about two seconds, so it was hardly anything really."

Reports on Twitter talked of one building in Bridgwater "swaying" during the quake while others said it was felt as far away as Taunton.

Ruth O'Malley, in Swansea, tweeted that there was a "definite rumble" from the quake and Ilfracombe Museum tweeted "the ground definitely shook just now".

Mid Wales Fire Service said it had received several calls while Avon and Somerset Police said it had not had any calls about the earthquake.