Today in History—April 14: The Volcanic Eruption That Grounded a Continent

On this day in 2010, Iceland’s Eyjafjallajökull volcano erupted in earnest.

Small earthquakes had been rumbling since January, and in March, the 5,417-foot-tall subglacial volcano at the southern end of the country concluded 187 years of dormancy with the beginnings of a quiet lava flow.

But on April 14 the eruption turned explosive, sending steam clouds, ash plumes, and lava “fire fountains” at 2,192 °F high into the sky. So high that it reached the airspace used by commercial flights.

By the next day ash had drifted over much of western Europe. By April 16 it had reached northern Europe. Air traffic ground to a halt, leading to the worst disruption since World War II: Some 300 airports closed, more than 7 million passengers were affected, and more than $1 billion was lost in revenue.

Ash—especially the fine-grained particulates thrown up by this eruption—does more than darken skies and create doomscroll-worthy maps of swirling brown clouds. It can also damage airplanes, clogging engines and potentially causing them to stall.

At least, in theory. We don’t often have volcanic eruptions smack in the middle of busy air travel routes (thankfully), which meant that, in 2010, we didn’t really know how much ash it would take to break a plane.

Most eruptions are far more localized than Eyjafjallajökull and easy enough to fly around. But not this one: Iceland does sit smack in the middle of several transatlantic routes, and prevailing winds carried ash clouds over major population centers, making it impossible to avoid.

Air traffic resumed after about a week, but the disruption was so massive that it inspired scientists and engineers to determine whether there was an acceptable level of ash for planes to fly through. The results suggested a threshold of 2 milligrams per cubic meter of air, along with low-, medium-, and high-risk categories that individual airlines and manufacturers in Europe now use to decide their ash tolerance.

Eyjafjallajökull’s eruptions continued into May. Meanwhile, thousands of visitors flocked to Iceland—once the airspace reopened—to see the ethereally glowy lava show, sending tourism numbers soaring.

These days the volcano is quiet. But some effects remain: Tourism is now one of Iceland’s biggest industries, kicked off, in part, by that time a volcano stopped the skies.