TU Delft co-author Nature article on Iceland vulcano

Illustration: Zina Deretsky, NSF et al. Free to use, click on the picture for hires version

Magma

When magma starts to rise, the Earth’s surface rises with it and becomes slightly stretched. Once the magma is expelled via an eruption, the Earth’s surface typically sinks again and contracts.
This is the principle used by scientists in geodetic research to map out and analyse the process of a volcano eruption. Movements in the surface of the earth can be detected and recorded to the millimetre using satellite-radar readings and GPS measurements.
This is exactly how researcher Dr Andy Hooper from TU Delft set to work on studying the Icelandic volcano Eyjafjallajökull, as the cloud of ash it emitted in April and May caused so many problems to the European aviation industry. Together with researchers from Iceland, America and Sweden, he will be publishing an article on this subject in the 18 November issue of Nature.

Lava eruption

''This Icelandic volcano had been rumbling for 18 years'', explains Hooper. ''Before the eruption in March, we recorded a magma movement from deep in the crust to a few kilometres beneath the crust. The magma was spreading out and forming a layer. Much the same happened in 1994 and 1999, but these incidents did not lead to an eruption.''
The magma was then slowly propelled upwards and on 20 March of this year, it finally reached the surface; the result was an eruption from the flank of the volcano. As the magma was still fairly fluid, most of the gas was able to escape before the actual lava eruption. This is why the first eruption in March was not very explosive.

Explosive

After the first eruption, Hooper had expected the Earth''s crust to sink and contract. However, he observed little further movement. ''This indicated that magma from deep in the Earth''s crust was on its way directly to the surface. This was confirmed when two days after the end of the first eruption, on 14 April, there was a more explosive eruption from the top of the volcano.''
This time, the magma was more sticky and contained more gas. The interaction with ice also enhanced the explosiveness. This eruption generated a cloud of volcanic ash, which rose to a height of 10 kilometres. After the second explosion, the scientists observed sinking and contraction of the Earth’s surface. The upper magma chamber was emptying (at least partly) and the eruption stopped after almost a month.

Predictions

One of the main aims of this kind of research is to be able to predict when a volcano will erupt. ''Research of this kind gives us a greater understanding of how volcanoes work and we hope that we will eventually be able to make more accurate predictions.''
''Predictions for a volcano like Eyjafjallajökull are more difficult than most. This type of volcano only erupts once every few hundred years (the last eruption was in 1823). It is easier to predict eruptions in more active volcanoes, as usually they are associated with pressure changes at only one magma chamber. The process is more complex in less active volcanoes.''

Katla

Hooper and his colleagues are currently keeping a close watch on the large neighbouring volcano Katla, (which last erupted in 1918). In the past, Eyjafjallajökull and Katla both became active at the same time. ''However, as yet there is nothing to suggest that Katla is about to erupt'', says Hooper.

More information

Dr. A.J. Hooper, A.J.Hooper@tudelft.nl, +31 (015) 27 82574

Click here for more background information and the lunch lecture held by Hooper on April 20th this year. The direct link to the lunch lecture: http://bit.ly/fhkfZK

Also see the article in Delft university newspaper Delta.

Science Information Officer TU Delft Roy Meijer, r.e.t.meijer@tudelft.nl, +31 (0)15 2781751