An earthquake which shook parts of the UK on Saturday was the biggest for a decade, experts said.
The British Geological Survey (BGS) said the epicentre was 20km (12 miles) north of Swansea, with a 4.4 magnitude at a depth of 7.4km (4.6m).
A BGS tweet added: "Around 3,000 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 today's event"
The BGS said an earthquake happened in the UK "every three to five years".
People across south Wales and south-west England said they felt what they thought was an earthquake this afternoon.
Shan Black said a campus at Swansea University was evacuated as a result of the tremors.
Mark Wyatt, a third-year student at Cardiff University, was entering his house in the city centre when he heard a "weird, deep rumbling sound" at around 2.30pm.
The 21-year-old told the Press Association: "We heard the noises before we felt the rumble, and then the house shook for a couple of seconds before it stopped."
James Leonard wrote on Twitter: "Wow was that an earthquake in Swansea my house just shook #earthquake earthquake."
Tremors were felt across the Bristol Channel into England too.
Seth Piper wrote on Twitter: "OK pretty sure I just experienced my first ever earthquake... in Bristol, UK?"