Sky News reports....A magnitude 4.1 earthquake has been registered centred three miles under the Bristol Channel.
A spokesman said: "It looks like there was an earthquake originating in north Devon at 13:21 so we are just analysing it."
The tremor is thought to have occurred at a depth of three miles (5km) and lasted several seconds.
The British Geological Survey (BGS) said residents reported their houses rocking and others described the quake as like a "heavy truck going up the road"
It was felt in areas including Dartmoor, Bristol, Taunton, Swansea, Llanelli, Barnstable and Gloucester, according to the BGS.
Robin Beer, on his Twitter page, wrote: "Anybody else feel the earth tremor just now?!"
Glenn Watts added: "Small tremor felt in Exeter, lasted five seconds armchairs wobbled as did the TV on its stand."
People in South Wales also reported feeling the ground shake. One Twitter user wrote: "Earthquake tremor in Wales today. We felt it in the building in Swansea."
Brian Baptie, from the BGS, told Sky News: "We get an earthquake of this size maybe roughly once every three years somewhere in the UK.
"It appears to have been felt fairly widely in Devon and South Wales.
"It is possible for earthquakes of this size to cause some minor, superficial damage, but we have no reports of that nature at the moment."
The European-Mediterranean Seismological Centre (EMSC) reported it was a magnitude 4.5 quake and was centred around the Exmoor National Park.