A volcanic eruption sent tons of ash and particles into the sky this week, stalling air traffic across Northern Europe. What do geologists know about the volcano’s eruption and what risks exist for the people of Iceland?



This is WEEKEND EDITION from NPR News. I’m Scott Simon.

Travel across Europe is at a standstill for a third day after a volcanic eruption in Iceland has clouded the skies. Flights have been cancelled, airports closed, thousands of passengers stranded. Scientists in Iceland are keeping a close eye on a volcano that began erupting on Wednesday. Not only does the ash pose a risk for aircraft, but as NPR’s Joe Palca reports, the eruption can cause serious problems in Iceland as well.

JOE PALCA: It’s mainly a case of bad luck that the volcano is causing so many problems for travelers trying to get around Europe. The eruption of Eyjafjallaokull – if you’ll forgive my pronunciation – is not terribly large as volcanic eruptions go, and had the winds been blowing a different direction, the world would have taken little notice.

But the bad luck continues. Gwytherin Nina Peterson(ph) of the Icelandic Meteorological Office says the winds are still westerly.

Ms. GWYTHERIN NINA PETERSON (Icelandic Meteorological Office): Which means that the winds are going from Iceland towards the rest of Europe.

PALCA: Still?

Ms. PETERSON: Still, and will be. The wind direction is going to change a little bit, but it’s still going to be air going from Iceland down towards Europe.

PALCA: There is a bit of good news. When we spoke on Friday, Peterson said the ash cloud wasn’t rising as high as it did at first.

Ms. PETERSON: The plume yesterday and today has mainly been in the lowest levels of the atmosphere. There seems to be a little bit less ash today than before.

PALCA: When the ash stays fairly low in the atmosphere, it doesn’t travel as far and it’s also possible in some cases for aircraft to fly over it.

The Icelandic Meteorological Office also employs geophysicists who are responsible for keeping track of the inner workings of the volcanoes in Iceland. Kristin Volfjord(ph) is one of those geophysicists. She says one of the ways of keeping tabs on a volcano is monitoring how much the ground around it is moving. To do that, they place instruments around the volcano whose location can be measured with extreme accuracy.

Ms. KRISTIN VOLFJORD (Geophysicist): One directly south of the volcano and another one north of it.

PALCA: Volfjord says for most of this year those instruments have been moving apart, suggesting the ground underneath them was ballooning out as it filled with magma. After the eruption, that changed.

Ms. VOLFJORD: And in the last two days, the station, both of them, have moved towards the volcano. So we are seeing that the volcano is subsiding a little bit. It hasn’t gotten back to the original position, but it is contracting.

PALCA: That could be a good thing, since it means the magma that was most poised to burst forth has done so. But there could be deeper magma yet to come, so Volfjord is loath to make any predictions about when the eruption will stop.

Ms. VOLFJORD: I don’t know. It could stop soon or it could continue intermittently for days or weeks or – I think the last one lasted for about two years, with quiet periods in between. so it’s difficult to say.

PALCA: Another worry is a larger volcano just to the east called Katla. That’s because eruptions from Eyjafjallaokull frequently occur just before eruptions of Katla.

Ms. VOLFJORD: I’m not sure you can assume that Katla will erupt this time, but it’s close to being due, because Katla erupts about once per century, and the last eruption was in 1918.

PALCA: Volfjord says for now there are no signs that Katla is going to erupt. Both those volcanoes are covered with glaciers, and eruptions can cause massive deadly flooding when the ice melts.

But Ergena Iwinskaya(ph) of the University of Cambridge says there’s another threat when volcanoes erupt: deadly gases, including gases containing fluoride. Fluoride can be good in small concentrations – it’s in toothpaste – but…

Ms. ERGENA IWINSKAYA (University of Cambridge): Fluoride is highly toxic. In high concentrations it starts to replace calcium in your bones.

PALCA: That’s not just bad for people. Livestock can be wiped out by the fluoride from volcanic eruptions. What’s an expensive inconvenience for European air travelers can be a deadly menace for people in Iceland.

Joe Palca, NPR News, Reykjavik.