Experts are investigating reports of an earthquake in the South West of Britain.
The British Geological Survey (BGS) said it was investigating reports of a quake centred on north Devon.
A BGS spokesman said: "It looks like there was an earthquake originating in north Devon at 13:21 so we are just analysing it."
The size of the tremor is not yet known but reports on Twitter suggest that it was felt in north Devon and South Wales.
Twitter user Robin Beer said: "Anybody else feel the earth tremor just now?! #ndevon #barnstaple #earthquake."
Ant Veal tweeted: "Noticeable earth tremor just now (13.22GMT) in Exeter. Lasted 3 seconds. #Devon #earthquake."
Glenn Watts added: "Small tremor felt in Exeter, lasted 5 seconds armchairs wobbled as did the tv on its stand."
People in South Wales also reported feeling the ground shake.
Someone using the name @BuskingWomble wrote: "Blimey did anyone else feel that tremor? #BurryPort #Llanelli."
Another user said: "Earthquake Tremor in Wales today. We felt it in the building in Swansea."
An update on the BGS website said the 4.1 magnitude quake originated in the Bristol Channel.