The largest eruption ever recorded, in Indonesia 200 years ago, wreaked havoc across the world, causing hunger, disease and death for years afterwards. When a volcanic event on that scale happens again – and it will – we should be prepared for serious disruption to our climate and food production
If you were one of the 10 million air travellers shaking your fist at the departures board in April 2010, you will appreciate the fact that – even in this tectonically peaceful realm – we ignore volcanic threats at our peril. Despite being nothing to write home about in terms of size, the eruption from Iceland’s Eyjafjallajökull volcano brought air travel chaos to the UK and mainland Europe when its ash cloud grounded an astonishing 107,000 flights in the biggest air traffic shutdown since the second world war. The eight days of mayhem brought airline CEOs to the point of apoplexy and, once the ash had settled, the air travel business was left with a €1.3bn bill. The threat posed by Icelandic eruptions has since been recognised and added,
retrospectively, to the UK’s National Risk Register, in the hope that next time we will be better prepared.
But what about volcanic explosions further afield? These, it appears, are still regarded as posing no threat to our country, and so can be safely ignored. But turn the clock back 200 years and there is at least one event that suggests we ought to think twice.
In April 1815, the biggest known eruption of the historical period blew apart the Tambora volcano, on the Indonesian island of Sumbawa, 12,000km from the UK. What happened next testifies to the enormous reach of the biggest volcanic blasts.
The Tambora volcano had shown no signs of life for 1,000 years; a single eruption in the previous five millennia provided the only indication that magma was still churning far beneath. It is very likely that the residents of the island considered the volcano extinct, and possible even that they did not know the impressive 4,300m (14,107ft) mountain – at the time, probably the highest in the East Indies – was a volcano at all. This all changed, however, with the rumblings and earthquakes of 1812, a full three years before the climactic blast. Over time, the seismic shocks were superseded by steam blasts and small ash explosions, engendering increasing trepidation on the island and signalling that something bigger might be imminent. It was. On 5 April 1815, a titanic explosion hurled a cloud of ash to a height of more than 30km. Violent, but short-lived, the blast lasted just two hours, after which the volcano returned to a state of brooding menace.
According to the lieutenant governor, Thomas Stamford (later Sir Stamford) Bingley Raffles, to whom volcanologists are indebted for his accounts of the eruption, the detonation was so loud that it was mistaken across Java for cannon fire, causing consternation among the British troops, which had ousted the Dutch and French forces just a few years earlier.
But the blast was small beer in comparison with what followed. After five days of relative calm, the climactic phase of the eruption began with a colossal explosion that launched a towering column of ash to the edge of space. For four or five days, utter blackness reigned across the island as the hurricane blasts of hot ash and scalding gas – known as pyroclastic flows – scoured the flanks of the volcano of everything and everyone, and drifts of ash metres thick entombed what few signs of life remained. When the explosions ceased and the darkness finally lifted, the view revealed was a vision of Tolkien’s Mordor; a grey landscape within which nothing lived or moved. The top 500m of the volcano was gone, blasted into smithereens, and replaced by a 6km-wide maw from which steam spiralled skywards. Communities on the flanks of the volcano had vanished, along with the lives of around 12,000 men, women and children. These, perhaps, were the lucky ones, as a further 60,000 survivors of the eruption succumbed slowly and agonisingly to famine or disease.
But the consequences were not confined to this Indonesian backwater. The explosion was heard 2,600km away in Sumatra, while giant rafts of floating pumice – some kilometres in length – clogged shipping routes for years. The 50 cubic kilometres or so of ash ejected over the course of the eruption returned to earth in the following days and weeks, leaving a thick covering as far away as Borneo, 500km to the north. In addition to the ash, an estimated 200 million tonnes of microscopic sulphur particles pumped into the stratosphere, spread outwards from Sumbawa to form a giant aerosol veil that enclosed the planet and acted as a block to incoming sunlight....MUCH MORE
Volcanoes: 10 to watch
Vesuvius has been quiet for 71 years.1 Laguna del Maule (Chile)
Currently inflating at the astonishing rate of 25cm a year, above a growing body of magma just 5km beneath the surface.
2 Uturuncu (Bolivia)
A 70km-wide bulge that has been growing since the early 1990s could culminate in a gigantic eruption.
3 Alban Hills (Italy)
Just 20km south-east of Rome, this huge volcano has started to become restless following more than 30,000 quiet years.
4 Campi Flegrei (Italy)
The archetypal “restless volcano” on the edge of Naples has not erupted since 1538, but has shown worrying signs, on and off, since the 1970s.
5 Yellowstone (Wyoming, US)
No eruption for around 70,000 years, but congenitally restless....MORE
-Erik Klemetti's Volcano blog at Wired
We have dozens of volcano posts including some that may be of interest to the non-specialist:
Hmmm... Krakatoa's Baby May be Getting Ready to Erupt
Isn't it About Time for Another Iceland Volcano? (Bárðarbunga dude)
Giant underwater volcano found off Indonesia
A Potentially Very High Risk, Very High Reward Agricultural Commodity Trade
World's Oldest Weather Report Found in Egypt: It Was Raining, People Were Crabby
Risk: Supervolcano Near Pompeii Could Have Globally Catastrophic Effects
What's New? There Was a Major eruption at Indonesia’s ‘Mountain of Spirits’ volcano
Volcanology: Indonesian Volcano Waking Up, Danger Zone Extended
