Tremors experienced for a few seconds.
The British Geographical Survey has been monitoring today's earthquake and analysing data.
It puts the epicentre approx 20km NNE of Swansea, with 4.4 magnitude at a depth of 7.4km. Events of this magnitude only happen in the UK every 2-3 years.
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
Seismologists have been sharing their quake data - this is today's event.
Swansea University's Bay campus was evacuated as a precaution.
The Bay campus of Swansea University has been evacuated as a precaution— 96.4 FM The Wave (@964thewave) February 17, 2018
(Picture - C&J) pic.twitter.com/WCDEMy2559
South Wales Police are urging people not to contact emergency services about the earthquake - unless they have something to report like injuries or damage.
The tremors were felt for a few seconds at around 14:35pm (Saturday 17th February).
We’ve had reports from members of the public in Resolven, Neath centre, Cimla, Tonmawr and even Bristol.
The British Geological Survey is asking anyone who felt tremors to fill in their survey - details here:
If you felt the tremors in the SW we’d be grateful if you could fill out our questionnaire. https://t.co/4i4RQzyYEg— BGS (@BritGeoSurvey) 17 February 2018
In Mayals some roofers were on scaffolding when the quake hit saying they couldn't believe what was happening.
Chris Norman lives in Swansea city centre he told us: "Being on top of a 12 storey apartment block wasn't the best. The building shook for about 10 seconds with a loud rumbling noise. You could see surrounding buildings shake in the opposite direction. I thought I was a goner!!!
People have been reacting to our post on Facebook - click link to read their stories.