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Iceland's Volcanoes: Katla, Eyjafjallajökull, Laki

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Map of Iceland's Volcanoes

The Mid-Atlantic Ridge (plate boundary) passes through Iceland from the southwest (Surtsey) and zigs its way northeast. Many of Iceland's volcanoes are under glaciers, melting the ice and causing massive floods when they erupt.

The Mid-Atlantic Ridge (plate boundary) passes through Iceland from the southwest (Surtsey) and zigs its way northeast. Many of Iceland's volcanoes are under glaciers, melting the ice and causing massive floods when they erupt.

Katla: Next to Erupt?

When you live on a geological hot spot that's merged with a plate boundary, volcanoes are a fact of life. Next up on Iceland's volcanic nuisance list may be Katla, a larger volcano than the Eyjafjallajökull volcano which spectacularly disrupted air traffic across Europe in April 2010, or the Grímsvötn volcano which raised concerns of a repeat scenario during its brief eruption May 2011.

The good news is that based on past history, if and when Katla volcano erupts, it will probably spew ash for only a month or two. The bad news is that it could spew ash and disrupt air travel for a month or two. Also, catastrophic floods and ash fall could spell trouble for hardy Icelanders for much longer than the ash cloud is causing an air traffic and news media perfect storm.

Also, of course, these aren't the only volcanoes in Iceland. The island straddles two tectonic plates, the North American and Eurasian plate, which are continually pulling apart and bubbling up new rock from the Earth's interior. Most of the volcanoes on the plate boundary are under the Atlantic, but Iceland itself is composed of 130+ volcanoes that have piled up enough rock to form a large island. Most of these volcanoes are local nuisances, but one, Laki, was a killer that devastated Europe in 1783-1784 and may have helped trigger the French Revolution!

Eruption Shock Waves

Eyjafjallajökull Volcano

This is the volcano that brought European air travel to a standstill for ten days in April 2010 and five in May, stranding people, mail, and air freight. When Eyjafjallajökull started spewing spectacular red fountains of lava on 20 March in the vicinity of snow and glaciers, it briefly proved a valuable tourist attraction. However, in mid-April and early May, air travel was disrupted by ash clouds drifting maddeningly to and fro across the UK, France and Scandinavia. The eruption petered out in May and had finished by May 23. This was good news, as the previous eruption of Eyjafjallajökull lasted for two years.

Eyjafjallajökull's impact to Europe made the news, but we tend to forget what the Icelanders went through. Ash continued to fall on Iceland after it cleared over Europe. Volcanic ash is pulverized rock, not wood ash, and is essentially ground-up glass. It gums up engine and electronics, ruins crops, irritates eyes and mucus membranes, causes respiratory problems, and kills animals that inhale or eat it.

Snow and ice melted by Icelandic volcanoes cause devastating floods, but thankfully most of the Eyjafjallajökull eruption took place from an area of exposed rock, causing minimal flooding. Katla is expected to trigger much worse flooding, capped as it is by a glacier.

Recommended links:

Demonstration of Volcanic Ash in a Jet Engine -- BBC Video

Volcanic Ash & Air Travel

Volcanic ash clouds are problematic for air travel for three reasons.

When sucked into jet engines, volcanic ash particles melt into glass and fuse onto engine parts, building up a layer of glass like ice on a windshield. This chokes the engine and may cause it to overheat, shut down or catch fire.

Unfortunately, volcanic ash clouds are difficult to avoid. The densest clouds are visible from space and can be mapped by satellite or radar, but in thinner concentrations — equivalent to cigarette smoke — they cannot be detected save by flying into them. Like water clouds, ash clouds are not uniform, so one can be flying through blue sky and suddenly hit a concentrated patch that's dangerous.

Third, we do not have reliable ways to know how much ash is too much, either for a one-time exposure, or for passenger planes which may have to pass through ash clouds again and again. It's not as if we can fly planes into volcanic ash clouds over and over to learn what circumstances make them crash. Therefore, air traffic regulators err on the side of caution, while air carriers worried about lost revenue push regulators to let them determine "acceptable risks."

Katla Volcano: Spectacular footage of glacial flooding

1918 Katla Volcano Eruption

Last eruption of Katla Volcano in 1918.

Last eruption of Katla Volcano in 1918.

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Katla Volcano: Overdue

The video above should tell you everything you need to know about Katla, and brings home graphically why Icelanders have cause to be worried. When a mountain of fire meets a mountain of ice, the result is practically Biblical.

Katla, a larger volcano, is just east of Eyjafjallajökull. Funny thing about Katla: it tends to erupt following each Eyjafjallajökull eruption. Then again, Katla erupts fairly frequently: usually every 40-80 years, but the last eruption was in 1918.

Scientists have been monitoring Katla closely since 2010. There have been many earthquakes under it in the summer and fall of 2011, attracting media notice. It looks like it's preparing for an eruption, but we cannot be sure how soon, how much, or how bad the flooding will be. The volcano may be capable of disrupting air travel again, since it tends to produce larger eruptions than Eyjafjallajökull.

Laki Fissure System

The Laki eruption did not take place at a single vent, but along a 17-mile-long fissure.

The Laki eruption did not take place at a single vent, but along a 17-mile-long fissure.

Laki Volcano: Toxic Eruption

Well, even if Katla erupts in the next year or so, at least Katla isn't Laki Volcano (aka Lakagígar). This monster makes recent eruptions look like sneezes. From 1783-1784, Laki devastated Iceland, covering 230 square miles with lava, 8000 square miles with ash fall, and pumping the atmosphere full of 219 million tons of toxic sulfur dioxide gas, causing sulferic acid to rain from the sky.

One fifth of Iceland's population died from the poisonous air and bitterly cold winter and famine that followed. Half the island's horses and cattle perished and most of their sheep. The toxic clouds and extreme weather killed approximately six million people across Europe. As far away as Egypt, one sixth of the population died from famines attributed to Laki's weather disruptions. Drought in India and failure of the rice harvest in Japan in 1783 have also been traced to Laki, since its cooling effects on the northern hemisphere disrupted wind and rain patterns globally.

Laki's noxious yellow fogs drifting across Europe were toxic to plants, livestock and humans. Navigation in many northern countries became impossible due to low visibility, shutting down boat traffic on seas and rivers. The volcanic clouds caused extreme weather in the northern hemisphere for several years, including bitter winters, exceptionally hot summers, violent hailstorms which destroyed crops, and El Niño conditions causing droughts across Africa and India. In North America, an extreme winter froze the Mississippi as far south as New Orleans and formed ice on the Gulf of Mexico. Scientists such as Ben Franklin gave accounts of the bizarre weather and mysterious fog.

The resulting famines, livestock die-offs and high mortality rates in the countryside caused widespread unrest, poverty and hardship. In France, where Marie Antoinette famously said, "let them eat cake," starving farmers were pushed to to the breaking point. The Laki volcanic eruption was not the sole cause of the French Revolution, but it was likely a contributing factor.

Thankfully, eruptions like Laki's are the exception rather than the norm. Unfortunately, sooner or later, there will be another.

Recommended Link: 18th-Century Climate Change: The Summer of Acid Rain - from The Economist, tracing worldwide impacts of the 1783 Laki volcanic eruption.

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Jose Juan Gutierrez from Mexico City on August 06, 2012:

It's a very informative article about Iceland's volcanoes and eruption dangers. Being Iceland a country that sits on so many volcanoes that have formed it, and in the middle of plate tectonism activity, the safety of people must be a subject of concern for the local authorities.

You have illustrated plainly many interesting points about iceland and its volcanic activity. Voted useful!

Kristin Trapp from Illinois on October 13, 2011:

This was a magnificent article. Volcanoes, as well as all other incredible acts of Mother Nature, are truly mind blowing. The force, power, and overall destructiveness are often enough to stop people in their tracks. Halting European air travel for multiple days is significant, yet somehow I missed the news of this volcanic eruption and its effects. It's awesome what can happen when a few plates shift, even in the smallest increments. Until reading your article, I was unaware of the number of volcanoes in Iceland. I now consider myself informed. Thank you.

Paul Cronin from Winnipeg on October 13, 2011:

Volcanoes are like crocadiles, ancient life still roaming the planet, facinating subject. Thanks for sharing!

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