How many UK earthquakes have struck, how often do they occur and why?
More than 5,000 people have been killed so far and thousands injured by a huge earthquake that struck south-eastern Turkey, near the Syrian border, in the early hours of Monday morning (February 6).
The earthquake, which hit near the town of Gaziantep, was closely followed by numerous aftershocks – including one quake that was almost as large as the first.
The early-morning quake and dozens of aftershocks brought down entire apartment blocks in Turkey and heaped more destruction on Syrian communities already devastated by over a decade of war.
The first quake struck as people slept and measured magnitude 7.8, making it one of the most powerful in the region in at least a century. It was felt as far away as Cyprus and Cairo.
More than 7,800 people have been rescued across 10 provinces, according to Orhan Tatar, an official with Turkey’s disaster management authority.
The UK is not immune to earthquakes either, the most recent having occurred in 2020.
When was the last earthquake in the UK?
In September 2020 a Bedfordshire town was rocked by two earthquakes in a day – and four in a fortnight. Residents reported their houses “jolting and shaking”.
The 3.0 and 2.1 magnitude tremors were centred on Leighton Buzzard at about 8.32am and shortly after 12.30pm on September 22, the British Geological Survey confirmed.
They were thought to be aftershocks following an initial 3.3 magnitude quake – since upgraded to 3.5 – leaving locals in shock.
“It was a bang and it was a shake, a real shake,” said Sheila O’Connell, an NHS worker who lives in Leighton Buzzard, while another said the tremors “almost shook me out of bed”.
In fact, the UK has more earthquakes than you might realise.
Why do earthquakes occur in the UK?
Glenn Ford, a seismologist at BGS, said that earthquakes happen regularly in the UK, we just don’t feel them.
“What's unusual about them is we only feel about 10 per cent. We don't really perceive the UK as a country associated with earthquakes so, when they occur, it can be quite disturbing,” he told the Standard.
“But it's very typical behaviour seen in the UK and we have had historical activity in that area. Most of them are so small people don't notice them.”
Mr Ford said Britain has about three earthquakes of 3.0 magnitude size each year, but that is one billion times smaller than the devastating 9.0 magnitude TÅhoku quake in Japan in 2011.
The Bedfordshire 2020 quake started deep underground in hidden fault lines, experts said.
Dr Matthew Blackett, a reader in natural hazards at Coventry University, called the Leighton Buzzard tremors “very, very odd”.
“What seems to have happened is that this was an initial earthquake in a hidden fault, some stress or other has caused it,” Dr Blackett said.
“These two subsequent events are a readjustment of the fault lines to come back to some sort of stability. The crust has to adjust itself to become stable again, that seems to have happened to the poor people of Leighton Buzzard.”
How many earthquakes have there been in the UK and how regularly do they occur?
The majority of earthquakes in the UK are so small they cannot be felt, because the UK does not sit on a fault line between tectonic plates.
Between 20 to 30 earthquakes are felt by people in the UK each year, according to British Geological Survey data, with hundreds of smaller ones recorded by sensitive instruments.
In the 50 days up to September 22, 2020, for example, a total of 39 earthquakes were recorded around Britain.
These ranged between minus 0.1 on the Richter Scale to the September 22 peak of 3.0, including a 1.0 tremor near Bristol city centre on September 4. Many tremors occur off the coast.
The Richter Scale is the globally recognised numerical scale for measuring seismograph oscillation, and destructive quakes typically measure above 5.5.
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 body's scientists added: “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's been the highest magnitude quake so far?
The largest known British earthquake occurred near the Dogger Bank in 1931, with a magnitude of 6.1.
Fortunately, it was 60 miles offshore but was still powerful enough to cause minor damage to buildings on the east coast of England.
The most damaging UK earthquake was in the Colchester area in 1884. Some 1,200 buildings needed repairs, chimneys collapsed, and walls were cracked.
The most recent serious earthquake, of 5.2 magnitude, struck Market Rasen in Lincolnshire in 2008 and was felt as far away as Newcastle and London.
Where else in Europe is prone to earthquakes?
Several areas in the Mediterranean have suffered serious earthquakes.
Italy is the European country most prone to quakes, with the Eurasian and African tectonic plates shifting at around 4mm to 10mm a year beneath its southern half.
These plates are not only responsible for some of Europe’s deadliest earthquakes, but also for Italy’s famous volcanoes: Vesuvius, Etna and Stromboli.
The most recent major quake to strike Italy was on August 24, 2016, when 6.2 magnitude tremors shook towns and villages 65 miles north-east of Rome in the early hours.
It claimed 297 lives and particularly ravaged the towns Amatrice and Arquata del Tronto. Nearly 4,000 people were made homeless as a result.
Dozens were feared dead in January 2017 after a series of four quakes, the strongest measuring 5.3 magnitude, shook buildings in Florence and Rome and prompted an avalanche that swamped Hotel Rigopiano in Abruzzo.
The deadliest documented earthquake in Europe was on December 28, 1908, when a 7.0 magnitude earthquake in the Messina Strait between Sicily and mainland Italy killed 72,000 people.
“The highest seismicity is concentrated in the central-southern part of the peninsula, along the Apennine ridge, in Calabria and Sicily, and in some northern areas, like Friuli, part of Veneto, and western Liguria,” said the Italian civil protection department.
The US Geological Survey added: “The region's tectonic activity cannot be simply explained by the collision of the Eurasia and Africa plates. It has been suggested that deeper lithospheric processes are controlling some of the deformation observed at the surface."
Spain, France, Greece and Portugal have also all suffered deadly earthquakes over the past three centuries.
The most recent was in May 2011, when at least eight people died when a magnitude 5.1 quake rocked southern Spain beneath the province of Granada.