Why is Britain experiencing so many earthquakes? Experts weigh in

From Cornwall and Wales to Essex, Blackpool and the Norfolk coast, Britain has experienced a flurry of earthquakes in the past month. 

The biggest – a 3.8 magnitude tremor that struck Wales on February 24 – sparked panic as locals reported their beds started to move and walls shook. 

One resident in the small Welsh town of Abertillery not far from the epicentre said the quake was so noticeable ‘it felt like the roof was falling off’.

The Welsh quake was preceded by several more including a 1.5 magnitude quake in Cornwall and a 3.8 magnitude event off the coast of Great Yarmouth. 

Here’s all you need to know about the British tremors – including whether recent tectonic activity suggests a ‘big one’ is soon to hit parts of the country. 

WHY DO EARTHQUAKES OCCUR IN THE UK? 

It’s well-known that earthquakes occur when two tectonic plates that are sliding in opposite directions stick and then slip suddenly. 

‘The Earth’s crust is made up tectonic plates that move relative to each other,’ Dr Jessica Johnson, a geophysicist at the University of East Anglia, told MailOnline. 

‘At the boundaries of these plates, rock moving past each other can build up stress due to friction and suddenly slide, resulting in an earthquake.’ 

Severe earthquakes – such as last month’s tragic event in Turkey and Syria – occur over fault lines where tectonic plates meet, but minor tremors can happen in the middle of these plates.

The UK is situated on a tectonic plate called the Eurasian Plate – but the nearest plate boundary to the UK, the Mid Atlantic Ridge, is around 1,000 miles away. 

In fact, the distance between Britain and America is widening by one and a half inches a year, due to upwelling in the Mid-Atlantic Ridge that’s pushing the Eurasian Plate and North American Plate apart.

HOW OFTEN TO EARTHQUAKES OCCUR IN THE UK? 

Between 200 and 300 small earthquakes occur in the UK per year, according to the British Geological Society, despite being distant from the nearest plate boundary.

Only somewhere between 20 to 30 earthquakes are actually felt per year and a few hundred smaller ones are only recorded by sensitive instruments. 

Most of these are very small and cause little to no damage, much less severe than in other parts of the world. 

According to the BGS, there have been about 40 separate tremors in the UK over the past 30 days – some too small to be noticed.

Public perception of how often quakes occur therefore may be influenced by social media and news reports. 

ARE THE RECENT UK EARTHQUAKES LINKED? 

Dr Richard Luckett, a seismologist at the British Geological Survey (BGS), says there’s no evidence the earthquakes across different parts of the UK are linked. 

‘Sometimes the UK does get regional swarms of tiny earthquakes which are linked, [but] these are very close together in time and space,’ he told MailOnline. 

Earthquakes are often followed by additional earthquakes, called aftershocks, which can be either more or less powerful than the mainshock. 

According to the BGS’s online database, there were multiple tremors of different magnitudes centred on the Cornish village of Constantine on February 24, including the 1.5 magnitude that was felt in Helston at around 6:30 in the morning. 

One Cornish resident tweeted: ‘The stone cottage I live in just shook!! Woke all the birds up too.’ 

But the other recent ones in other parts of the country are too far away to be directly linked, according to experts. 

‘The flurry might seem unusual,’ Dr Maximilian Werner, Associate Professor of Geophysics and Natural Hazards at the University of Bristol, told MailOnline.

‘But is almost certainly the result of a coincidence of seismic activity in different regions of the UK that just happened to occur within a relatively short time window. 

WHERE WILL THE NEXT UK QUAKES OCCUR? 

A temporary increase or decrease in seismic events globally is part of the normal fluctuation of quake rates, so the recent quakes offer no clue as to where the next one will happen. 

Dr Werner explained that ‘earthquakes cannot be predicted’.

‘We cannot say with certainty where the next UK quake will be,’ he told MailOnline.

Globally it is known that most of the damaging earthquakes will concentrate at the plate boundaries – but there is no reliable method of accurately predicting their time, location and magnitude. 

Using artificial intelligence (AI) techniques like machine learning isn’t much use because such technology looks for patterns to make conclusions. 

One can estimate the chances statistically, based on past occurrences, but these aren’t always accurate. 

WHEN WILL THE UK EXPERIENCE ‘THE BIG ONE’? 

‘The big one’ is a term often used to describe an earthquake that could cause significant damage or fatalities in a given area. 

But compared with the UK, places such as New Zealand, California, Italy, Turkey, China and Japan are at much greater risk. 

Dr Werner said the chances of a ‘big one’ happening in the UK are ‘very small’ –although not zero so ‘we should always be prepared’. 

Dr Luckett added: ‘On average, we expect one earthquake of magnitude 5 or over around every eight years. 

‘This is not big by global standards.’ 

On its website, BGS provides estimates of the chances of experiencing ground shaking levels over 50 years – the typical service life of a building. 

WHERE HAVE THE BIGGEST UK EARTHQUAKES BEEN? 

None of the recent UK quakes have come close to the magnitude of Britain’s record-holding tremors. 

The last significant British quake was 5.2 magnitude, and hit around 2.5 miles (4 km) north of Market Rasen, Lincolnshire, 15 years ago. 

People all over the country, including the south of England, felt the 10-second tremor shortly before 1am on February 27, 2008. 

Those old enough may also remember the 1984 earthquake in Llŷn Peninsula, Wales, the largest onshore UK earthquake since instrumental measurements began. 

The most destructive earthquake in the UK for several centuries was in Colchester in 1884, with a magnitude of 4.6 which caused considerable damage to churches. 

But the largest known earthquake in the UK happened offshore in the North Sea on 7 June 1931, with a magnitude of 6.1.

Its epicentre was in the Dogger Bank area about 75 miles North East of of Great Yarmouth.

A woman in Hull died of a heart attack, apparently as a result of the earthquake, while a non-destructive tsunami wave was reported to have hit the east coast. 

If a quake of magnitude 6 or above were to occur in the UK again, would we be prepared?

‘A magnitude 6 would be likely to cause significant damage to older buildings and infrastructure, and substantial disruption, especially in urban areas,’ Dr Werner told MailOnline.

‘Better preparedness is possible, of course, but would require significant investments in improving older buildings. 

‘Whether the relatively small chance of such an event would warrant such levels of investments depends on many factors, including the relative risks compared to other natural hazards – such as floods, droughts and storms.’