Eruption in Holuhraun and air quality considerations

The eruption in Holuhraun (Holu-lava field) has now been active for just over a week; since 31 Agust (if I remember correctly).

There is a fair bit of lava that has been extruded, as can be seen on this Landsat image from NASA. The lava flow is to the right on the figure, from a linear almost N-S fissure. There is a little red spot south of there, that is a new opening. There is a dike running from Bárðarbunga, underneath the glacier, to the eruption site (and even a bit further north). On of the things to look for is whether the fissure will open up underneath the glacier. Some flooding would follow and more explosions as magma and water interact.

Landsat 8 image from NASA on 6 September 2014.

The lava has reached the glacial river, Jökulsá á Fjöllum, which causes some steam explosions – making it still more difficult for the scientist working in the area.

But, one of the concerns, is the air pollution. Especially SO2 gas.

SO2 in 8 km of the atmospheric column (NASA).

Fortunately, this is a relatively small eruption.

Measurements in the eastern fjords, at Reyðarfjörður (large fjord middle of image), went up to 250 µg/m3 10-min value on 2 September. That is quite high, given that it is 125 km away from the eruption site, and this is a small eruption.

However, public health limits are 350 µg/m3 for 1-h average, and workers occupation limits are about 5 times higher than that. And real danger, requiring evacuation, seems to be at levels of 10 000 µg/m3.

Recent measurements in the eastern fjords indicate that the SO2 concentration is below 300 µg/m3, despite a distinctive blue haze being observed in the area. The haze can be seen quite clearly in the next figure.

MODIS image from NASA and IMO from 6 September 2014 at 13:30.

It will be interesting to follow the eruption and see whether: 1) the dike breaks to the surface underneath the glacier, 2) Bárðabunga will erupt, 3) Askja wakens, and erupts, or 4) the whole system simply slowly cools down.