One of Iceland’s most active and most famous volcanoes may be close to erupting. Volcanologists are keeping a watchful eye on Hekla, a mountain in south-central Iceland where magma is building up underground.

There is now more molten rock below Hekla than there was before it last erupted, in 2000, says Freysteinn Sigmundsson, a volcanologist at the University of Iceland. That suggests Hekla is primed to go off in the near future.

The good news is that researchers from the Icelandic Meteorological Office and the University of Iceland are listening to the mountain’s heartbeat. Hekla is one of the featured volcanoes in the Futurevolc project, a 3½-year, pan-European effort to beef up monitoring at Iceland’s riskiest volcanoes. The landscape around Hekla is peppered with the latest instruments to measure earthquakes, ground deformation, and other changes that could signal an impending eruption. If the volcano twitches, scientists know about it.

The bad news is that Hekla is just one of about 35 active volcanoes across Iceland. Until the spring of 2010, hardly anyone worried about a mountain called Eyjafjallajökull. It had been slumbering quietly since 1823. Then in April 2010, molten rock suddenly shot upward and ploughed into the glacier that caps the volcano. Hot rock and frozen water reacted explosively, and huge plumes of volcanic ash billowed into the sky. Wind and weather patterns were just right to carry the ash south and east towards Europe, where aviation officials had to close airspace for days.

Eyjafjallajökull triggered a level of travel chaos that Europe had never seen before. But Iceland’s volcanoes can do far worse. For centuries they have spread ash and toxic gases across Iceland and beyond. Peat bogs in Northern Ireland, for instance, record layer after layer of ash from Icelandic eruptions dating back millenniums.



Deadliest eruption

One Whitsunday morning in June 1783, the ground ripped open near Iceland’s southern coast. This particular eruption, of a volcanic fissure known as Lakagígar or simply Laki, was to become the deadliest in Iceland’s history. Along with enough lava to bury Manhattan 250m deep, it spewed huge amounts of toxic gases. Over the course of eight months Laki belched an estimated 122 million tons of sulphur dioxide into the air, making it one of the biggest atmospheric pollution events in centuries.

Just as happened with Eyjafjallajökull’s ash four years ago, the choking fog from Laki travelled south and east. The haze descended across Britain and Ireland, Scandinavia and much of the rest of Europe, where it lingered visibly for months. Plants withered in the volcanic poison. People breathing the fumes complained of stinging sensations in their lungs – then they, too, began to die. Census officials in England, France and elsewhere chronicled death after death that they could not explain. “The summer of . . . 1783 was an amazing and portentous one, and full of horrible phenomena,” wrote the naturalist Gilbert White.

The winter that followed was horrible in its own way. Unknown to anyone at the time, Laki’s sulphurous particles were reflecting sunlight back into space, acting as a giant cooling umbrella over much of Europe. The continent cooled, and temperatures plunged to record lows. The old, the sick and the vulnerable succumbed to a second wave of killing from Laki.

When the spring thaw began, ice-choked rivers began breaching their banks. In eastern Ireland, the rivers Dodder and Avoca flooded, carrying away farmers’ homes and property. The scene was repeated across Europe. Farther afield, Laki’s cooling particles disrupted weather patterns across the northern hemisphere, shutting down the African monsoon and triggering famine in Egypt.

By the time Laki finished erupting, nearly a quarter of Iceland’s population had perished, most from hunger after volcanic toxins poisoned their fields and their livestock. Worldwide, the death toll may have stretched into the millions.



A taste of what’s to come

Today, scientists recognise the Laki eruption as an important example of the kind of devastation that Icelandic volcanoes can wreak. The 2010 eruption of Eyjafjallajökull was just a taste of what’s to come. By almost any measure, the 1783-1784 Laki eruption was not unusual. Something like it could happen tomorrow.

A Laki-type eruption happens in Iceland on average every 200-500 years, and it has been 230 years since the last one. Volcanoes don’t erupt in precise cycles, but they do provide clues when they are about to blow. And that’s where projects like Futurevolc come in.

With instruments all over the sides of Hekla and other Icelandic volcanoes, researchers are better prepared to know when an eruption is coming. They won’t get much warning – something like minutes to hours is the most we can hope for. But it’s a lot more than anyone had in the 18th century, and a testament to where modern science has brought us.



Alexandra Witze and Jeff Kanipe are authors of the new book Island on Fire: The Extraordinary Story of Laki, the Volcano that Turned 18th-century Europe Dark (Profile Books, 2014), lakithebook.com





LAKI ERUPTION: WHAT WOULD THE FALLOUT BE?



The transport meltdown that followed Eyjafjallajökull’s 2010 eruption would be nothing compared to the chaos after a Laki-style eruption, scientists say.

Atmospheric modellers have calculated that, if an eruption like the 1783 outburst happened tomorrow, some 142,000 people across Europe would die.

Most would perish from respiratory ailments such as asthma or congestive heart failure; most of the dead would be the elderly, sick and otherwise vulnerable.

Imagine a world where grandmothers are dying in hospitals stretched to the limit. Water supplies are tainted with volcanic toxins. Livestock are getting sick and dying at levels reminiscent of foot-and-mouth outbreaks. Meanwhile, key medical equipment is grounded in other countries, as ash clogs the airspace over Europe and restricts flights.

It may sound far-fetched, but two years ago the UK added the threat of Icelandic volcanoes to its National Risk Register, as an acknowledgement of the planning it has yet to do.

The British Geological Survey recently sketched out several disaster scenarios. One possibility is an Eyjafjallajökull-type eruption, with the biggest impacts on travel and trade. The grimmer possibility is a lengthy eruption that fouls the atmosphere with lots of gases and aerosols, as Laki did. To help officials get ready, the British team recommended improving air-quality monitoring in far-flung regions of Britain, to sniff for volcanic gases on the move.

“The government needs to prepare in a sensible way,” says Susan Loughlin, a volcanologist at the British Geological Survey in Edinburgh who led the study. “They need to know the risk, better understand what the risk is, and give a proportionate response to that.”