Britain was hit by its biggest earthquake in a decade today.
The British Geological Survey (BGS) said tremors were felt across parts of Wales and southwest England, but no notable damage was reported.
The BGS said the quake was of magnitude 4.4, with an epicentre 20km north of the Welsh city of Swansea.
It was the biggest quake in the Britain since 2008.
Earthquakes are not common in the UK and are rarely powerful.
The 2008 quake in Market Rasen, in the north-east of England was magnitude 5.2, 16 times more powerful than today's quake.
Today's earthquake was felt across parts of Wales and as far away as Carisbrooke Castle on the Isle of Wight, over 200 km away.
Videos on social media showed people gathered outside Swansea University, which was holding an open day, after an apparent evacuation.
Tremors were also felt across the Bristol Channel in England too.
On Twitter, the BGS said events of this magnitude only happen in the UK every 3-5 years.
According to the BGS, today’s quake was the biggest event of its kind in the area since 1906.
In relation to this afternoons event:— BGS (@BritGeoSurvey) February 17, 2018
Around 3000 event of this size in the world every year
Biggest onshore UK event in 10 years, since 27 Feb 2008 Market Rasen eq 5.2 ml 16X bigger than todays event
Approx. 8 million times smaller than the magnitude 9.0 in Japan March 2011
This is the biggest event in the area since the 5.2 magnitude earthquake in 1906. pic.twitter.com/zq9JEIttQI— BGS (@BritGeoSurvey) February 17, 2018
Following the quake, police in Swansea appealed to people not to contact their local emergency services unless they had injuries or damage to report.