Volcanologist Martin Mangler explains the surprising relevance of volcanoes to London.
Volcanoes – enigmatic and magnificent, beautiful and dangerous: true wonders of nature. Victorian Londoners were so desperate to possess one that, in 1846, they pragmatically built their own volcano, just off the Walworth Road.
But what actually is the closest volcano to London, and what would happen if it were to erupt?
What is the nearest active volcano to London?
It’s a tight race between Vesuvius in Italy and Öræfajökull on the southeast coast of Iceland – both are just over 1,000 miles from London. Vesuvius wins the prize by some 30 miles, and it certainly is an impressive nearest volcanic neighbour to have.
That being said, prevailing westerly winds in the UK mean that we are unlikely to be directly affected by an eruption of Vesuvius – unlike Icelandic volcanoes. Öræfajökull, which last erupted in 1728, is located in the East Volcanic Zone, a particularly active region that also includes the infamous Eyjafjallajökull and Grímsvötn volcanoes. Both have caused severe disruption to air travel in recent years.
Many will remember those days in spring 2010, when Eyjafjallajökull erupted. Airports were closed, people were stranded, and hate-chants were directed against Iceland. Just about a year later, Grímsvötn pulled the same feat, with many flights cancelled across Europe.
How can Icelandic volcanoes disrupt air traffic in the UK and Europe?
Lavas erupted in Iceland tend to be very hot and runny — up to 1,200 °C. They often form picturesque lava fountains that are generally not dangerous.
But here’s the nasty thing: The East Volcanic Zone is not only packed with lava spewing mountains, but also with glaciers putting an icy lid on many volcanoes, including Katla, Eyjafjallajökull and Grímsvötn. Every time these volcanoes expel lava, it encounters a huge package of ice, and the result is explosive.
The lava melts the ice almost instantaneously, producing hot water vapour that then mixes with the lava to form huge clouds of ash. More often than not, the wind blows straight from Iceland towards the UK and mainland Europe. Volcanic ash (tiny particles of volcanic glass and mineral fragments) can block the air supply of jet engines and cause them to fail. As soon as there is a critical amount of ash in the air, planes are grounded.
How can distant volcanoes influence our climate?
It’s not only those ice-capped beasts that can cause devastation in the UK. In 1783, a large new fissure called Laki opened in the East Volcanic Zone, erupting a staggering amount of lava over the course of about eight months. At the same time, about 120 megatonnes of sulphur dioxide and other volcanic gases were released into the atmosphere.
This volcanic haze then travelled towards the UK. Its effects can be seen in the historical record: mortality peaks registered in the east of England in the months following the onset of the eruption, and written records describe a 'peculiar haze, or smokey fog' that obscured the sun and caused extreme temperatures and failed crops in 1783. Imagine an entire summer of intense smog. That's what volcanoes can do, even at a distance of 1,000 miles.
And even volcanoes on the other side of the world can change the climate for months or even years. If volcanic particles reach the upper layer of the atmosphere, they can travel around the world for years, all the while absorbing and scattering the light from the sun.
When Tambora volcano erupted in Indonesia in 1815, it caused a global decrease in sunlight and temperature in the years after. The gloomy weather allegedly inspired Mary Shelley to write Frankenstein. Similarly, the eruption of Krakatau volcano in Indonesia in 1883 caused a worldwide decrease in temperatures. Londoners noticed peculiar side-effects, such as frequent red sunsets and blue moons.
Are there any extinct volcanoes closer to London?
Ancient volcanoes can be found much closer to home than Iceland. The closest is a mere 70 miles north of London near Warboys. So how come you’ve never heard of them?
Most have not been active for 400-500 million years, when Scotland and England were part of separate continents drifting towards each other. The tectonic movements came with vigorous volcanism, which shaped the landscapes of Snowdonia and Glen Coe. The latter was a veritable supervolcano of Yellowstone dimensions.
Volcanic activity at Glen Coe, for example, would have created a whole different set of problems had London existed back then. Volcanic ash would have blanketed the city, creating blackouts, compromising fresh water supply, collapsing roofs, and causing widespread respiratory problems much worse than the infamous London smog. And of course, most importantly, it definitely would have shut down the tube.
Luckily for us, these volcanoes became extinct long ago, when the magma supply from beneath stopped. The last volcanic activity on mainland UK took place around 55 million years ago, when the Atlantic ocean opened, forming the world famous Giant’s Causeway in Northern Ireland.
So does the UK have any active volcanoes?
No active volcanoes can be found on mainland UK, but there are some on British soil. To be specific, the British Overseas Territories of Montserrat in the Caribbean, Tristan da Cunha and Ascension Island in the middle of the Atlantic, and the Sandwich Islands close to Antarctica. All host active volcanoes.
Soufrière Hills volcano on Montserrat started erupting in 1995 and buried the island’s capital Plymouth in ash, rendering much of the island uninhabitable and permanently displacing a large proportion of its population. That volcano is not currently erupting, but it’s closely monitored.
Mt Michael on the Sandwich Islands, a volcano so remote and hostile that no one has ever reached its summit, recently made headlines when satellite data revealed that it has a persistent lava lake. This makes it one of only eight volcanoes with this Hollywood-esque feature.
While we might not have to worry about lava flooding Piccadilly Circus anytime soon, volcanoes all over the world have the power to affect our daily lives. So the next time an unpronounceable volcano in Iceland messes with your travel plans (and it will happen at some point), why not save yourself the journey to the airport and explore the magnificent Volcanoes and Earthquakes exhibition at the Natural History Museum instead.