A 4.4 magnitude earthquake, which only happens every two to three years in the UK, has hit Wales.
The quake’s epicentre was 10km north east of Swansea, according to monitors EMSC and its tremors were felt across western Britain.
The British Geological Survey said it was the largest quake in the area since 1906.
It said a quake of this size happened in Britain only once every two or three years.
The BGS said that about 3,000 events of this size take place every year.
Today’s earthquake was the “biggest onshore UK event in 10 years” and 8 million times smaller than the magnitude 9.0 in Japan in March 2011, the BGS said.
People reported feeling the tremor in Bristol, Cardiff and Swansea among other places.
Students at Swansea University were evacuated from their campus.
The Met Office reported feeling it in their headquarters in Exeter.
EMSC estimated 10 million people lived in the area where the quake could be felt.
Dyfed Powys Police said it was getting “an extremely high call volume” about the tremor but told people: “There is nothing to worry about.”
Jennie Griffiths, the head of joint fire control for South Wales, shared on Twitter some examples of the calls the emergency services received from residents after they felt the tremors.
HuffPost UK reporter Kathryn Snowdon was in a cafe in Swansea city centre at the time the earthquake struck.
She said: “It suddenly felt as though the whole building was shaking for a few seconds. It was a little scary at first but it was over with so quickly that no-one was really sure what had just happened.
“Some thought it was just very windy outside and others thought that a large vehicle was passing nearby.
“It wasn’t until we started searching on social media that it became clear it was an earthquake which could be felt across the rest of south Wales and England.
“There aren’t any signs of damage and people look to be carrying on as normal.”
Rory Castle Jones, who lives in Craig-Cefn-Parc, just outside Swansea, told HuffPost UK: “We felt the house shake and heard a rumbling. I’ve never experienced an earthquake before and had no idea what it was.
“We thought maybe it was a mine shaft collapsing or something.”
Emily Perkins, who lives in Bristol, said: “I was at home in our flat just around the corner from Temple Meads, and the whole building shook - far more than you’d expect from a heavy lorry or a freight train.
“It felt like the whole building was pushed to the side, with mirrors shaking. There isn’t any damage in the area that we can see, but I wouldn’t be surprised if some buildings have structural issues discovered later.”