How Iceland’s Eyjafjallajokull volcano finally blew its top Iceland’s Eyjafjallajokull volcano is in the second phase of an eruption that began last month. The eruption started when subterranean liquid rock -magma -found a weak spot in the earth’s crust and burst through. Because of its location between glaciers, the eruption was largely ash-free.
But then a second, more powerful eruption followed, through a rupture close to the volcano’s glacier-covered summit. Fire met ice and fire won. Huge amounts of ice melted and flash floods followed. Once the eruption melted away the icy lid, some 150m (492ft) thick, the volcano began to belch ash into the atmosphere.
As magma rises from the earth’s bowels, it experiences a pressure drop. Gas dissolved in the magma starts to emerge and forms bubbles, as it does in champagne when the cork is released. When the boiling fragments of magma hit cold air and water, they freeze into dust particles, driven high up into the atmosphere by the power and heat of the eruption.