Richard Luckett, from the British Geological Survey, has described today's earthquake as "fairly unusual", adding that a magnitude of 4.1 is large for the UK.
Did you feel an earthquake this afternoon in Swansea, Llanelli or another area of south-west Wales?
The British Geological Survey is asking people to share their experiences to help them build a better picture of the quake.
The map above, in its early stages, shows the intensity of the earthquake felt in different areas.
You can add your observations by visiting the British Geological Survey's website here.
The British Geological Survey has released more information about this afternoon's earthquake in the Bristol Channel, felt by people across south-west Wales.
- Date: 20/02/2014
- Origin time: 13:21:30.2 UTC
- Location: 51.361 -4.184
- Depth: 5km
- Magnitude: 4.1
- Locality: Bristol Channel
The BGS added that the epicentre of the quake was approximately 30km southwest of Swansea and around 18km north of Ilfracombe in North Devon.
An earthquake felt by Swansea and Llanelli residents happened at 1:21pm today and was 4.1 magnitude, the British Geological Survey has confirmed.
The Bristol Channel quake was also felt in Dartmoor, Bristol, Taunton, Exmouth, Barnstable, Gloucester, South Molton.
The British Geological Survey has asked anyone who felt today's brief earthquake in the Swansea and north Devon areas to answer some questions about their experience.
Details coming soon re: quake off shore of North Devon. Fill out questionnaire if you felt anything http://t.co/3bsXWg7WHZ
There has been an earthquake in the Bristol Channel, the British Geological Survey has confirmed.
The quake was felt by people living in parts of Swansea and Devon.
A BGS spokesperson told ITV News they are investigating.
No further information is available at this time.
Did we just have a little earthquake in Swansea? The walls of my house & all my furniture just shook for like 3 seconds. Weird.
Erm, anyone else in the Swansea area just felt their house move? #earthquake?