Experts say the quake had a magnitude of 4.4, a depth of 7.4km and happened just after 2.30pm on Saturday.
People across the country reported feeling the tremor, with some as far north as Blackpool wondering what it was, the Mirror reports.More news: Arnold Schwarzenegger Cast in Kung Fury Movie
Tremors were felt across the Bristol Channel into England too.
"I phoned my parents in Ogmore Vale and they got out on the doorstep and all the neighbours were out asking 'what's happening?'"
The 21-year-old said: "We heard the noises before we felt the rumble, and then the house shook for a couple of seconds before it stopped".More news: Johnny and Daniel face off again in first 'Cobra Kai' teaser
"The ground moved quite alarmingly and, at first, it was not clear exactly what it was and inquiries were made with the emergency services to check if there had been a gas explosion or water burst underground".
What has been described as a minor natural disaster hit with a 4.4 magnitude and affected parts of Wales and England at around 2:31pm today, Saturday 17 February.
Baglan resident Meyrick Sheen told Wales Online: "We have lived here for 40 years and we have never experienced anything like this before, it felt like a massive explosion under ground".More news: Google finally unveils Gmail Go for low-RAM devices