Ash Flow

The Volcan Reventador volcano erupted in 2002, emitting a plume of ash unlike anything seen before-and potentially more dangerous. Now, a team of University of Illinois researchers has published a groundbreaking theory explaining why the plume from this volcano in Ecuador was scallop-shaped, producing highly dangerous ash flows. Normally, volcanic plumes appear in a mushroom-shape that resembles the blast cloud of an atomic bomb.

Susan Kieffer, a professor of geology in the College of Liberal Arts and Sciences, Gustavo Gioia, professor of theoretical and applied mechanics, and graduate student, Pinaki Chakraborty, theorized that the shape of this cloud might be a result of steam and cool ash from the destruction of the summit cone. The cool materials would have slowed the rising of the volcanic plume and altered its shape.

According to Kieffer, a normal, mushroom-shaped volcanic plume produces gradual ash flows, but a scallop-shaped cloud may behave differently. In fact, the U. of I. analysis showed that the Reventador plume "collapsed rapidly, forming new and especially dangerous ash flows," Kieffer says.

"For all we know, these flows were responsible for broken petroleum pipelines," Chakraborty adds. "The flows might also have contributed to the early phases of a shutdown of Quito airport that lasted more than a week."