The tremor – which occurred at 11.59 pm on Friday, February 24 – was of a 3.8 magnitude (Google’s Android Earthquake Alerts System recorded it as a 4.2 magnitude).
According to the European-Mediterranean Seismological Centre (EMSC), the quake occurred at a depth of two kilometres at 23:59:39 about eight miles north of the Rhondda Valley.
Although its exact location was Llangenny – small village on the slopes of the Sugar Loaf Mountain – tremors were reportedly felt as far away as Wolverhampton and Dudley in the West Midlands.
BRYNMAWR, GWENT 24 FEBRUARY 2023 23:59 UTC 3.7 ML
ORIGIN TIME: 23:59 41.5s UTC
LAT/LON: 51.829° North / 3.271° West
GRID REF: 312.4 kmE / 215.3 kmN
MAGNITUDE: 3.7 ML
LOCALITY:Brynmawr, Gwent (approx. 12km northeast of Merthyr Tydfil)
INTENSITY:5 EMS pic.twitter.com/da1UeRnaMH
— British Geological Survey (@BritGeoSurvey) February 25, 2023
In a statement released on Saturday morning, the UK’s main provider of earthquake data, the British Geological Survey wrote:”BGS has received reports from residents throughout the region, mainly from within around 40km of the epicentre.
“Reports described “the whole house was shaking”, “the rumbling and the bang woke me up”, “my bed seemed to move side to side”, “was like a large explosion”.
Earthquakes happen in the UK more often than you may have thought, with the last occurring as recently as 2020.
When was the last earthquake in the UK?
Leighton Buzzard in Bedfordshire recorded two earthquakes in a day – and four in a fortnight – in September 2020.
The tremors were of a 3.0 and 2.1 magnitude and they occurred at approximately 8.32am and then 12.30pm on September 22, the British Geological Survey reported.
It was thought they were aftershocks from a proceeding quake of an initial 3.3 magnitude which was later upgraded to 3.5.
How many earthquakes have there been in the UK and how regularly do they occur?
Since the UK does not sit on a fault line between tectonic plates, the majority of earthquakes experienced in the UK tend to be small and cannot be felt.
There are approximately 20 to 30 earthquakes that can be felt by Brits each year, according to the BGS.
However, there are hundreds of smaller ones that are recorded by sensitive instruments.
Earthquakes are measured on the Richter Scale which is an internationally recognised measurement of seismograph oscillation.
The more destructive tremors typically measure above 5.5 on the scale.
The British Geological Survey said: “A magnitude four earthquake happens in Britain roughly every two years. We experience a magnitude five roughly every 10–20 years. Research suggests that the largest possible earthquake in the UK is around 6.5.”
The scientists continued: “The driving forces for earthquake activity in the UK are unclear; however, they include regional compression caused by motion of the Earth’s tectonic plates, and uplift resulting from the melting of the ice sheets that covered many parts of Britain thousands of years ago.”
What is the biggest earthquake recorded in the UK?
The largest known earthquake in the UK is the North Sea earthquake of June 7 1931, according to the BGS.
It recorded a magnitude of 6.1ML and its epicentre was located offshore in the Dogger Bank area which is approximately 120 km northeast of Great Yarmouth.
It was felt by most of Great Britain, the east of Ireland as well as parts of continental Europe including northern France, northwest Germany, the Netherlands, Belgium, Denmark and southwest Norway.
Damage in Britain was reported from 71 different places, BGS said.