There were also reports in north Wales, with some claiming they felt the tremor in Broughton, Flintshire, and Llangollen, Denbighshire.
People across south Wales and south west England said they felt the natural disaster this afternoon.
The quake, which measured 4.7 on the Richter scale, happened at 2:31pm around eight miles from Swansea in South Wales.
The US Geological Survey & British Geological Survey confirmed an quake of 4.7 magnitude was recorded at 2.31pm.
One witness, just 4km from the epicentre told EMSC: "Genuinely thought next door had fallen down or the roof had caved in".
A huge natural disaster has hit Britain this afternoon.
Videos on social media showed people gathered outside Swansea University, which was holding an open day, after an apparent evacuation. At first, many weren't sure if they had experienced an quake.
"The whole building just rocked", said a tweet from the club in Rhondda Cynon Taff.
What is thought to have been the biggest quake in the United Kingdom for a decade has been felt across Cornwall.
So far there have been no reports of major damage or injuries.
But not everyone felt the earth move, with others complaining they had missed it.