Why Icelandic volcano still wreaking havoc.

• Position: Aviation

In light of the Icelandic volcano eruption that is responsible for one of the most costly, widespread, and ongoing aviation crises on record, how is this volcano able to cause such a travel nightmare? Eyjafjallajokull's ash plume stalled aviation over Europe for more than five days--and intermittertly since--because of the interaction between ice and lava during the eruption, as well as the lava composition, which is unique and influenced by the country's glacial nature.

Eyjafjallajokull is a subglacial volcano, meaning the eruption occurs beneath the surface of an ice sheet. The heat of the lava has the power to melt overlying ice, making it flow much more easily. "The eruption did migrate to be subglacial, and that interaction with the glacial ice has been more explosive through fragmentation of the lavas," explains Peter La Femina, associate professor of geosciences at Pennsylvania State University, University Park.

The volcano erupted in separate phases, with the first relatively calm phase taking place March 20. However, the eruptions within the second phase occurring on April 12 were much more violent and spewed out a much different type of lava. This dramatic change in eruption was possible because volcanoes emit lava of different consistencies, but predicting what type of consistency will result from an eruption is difficult. The interaction between the lava and the surrounding ice gives off steam, which propels ash more explosively than the slow-moving, shallow eruptions as exhibited by Hawaiian volcanoes. Steam-powered explosions can propel ash thousands of feet into the Earth's atmosphere and, in Eyjafjallajokull's case, ash clouds were...