Unless you're eating breakfast, hearing snap, crackle, and pop may be an early warning sign of an impending avalanche. Geologists listening in on "icequakes" that rumble through glaciers have developed a model that can predict a collapse up to 15 days before it happens, the team reports in a study posted on arXiv.org.
With that kind of heads up, villages could be evacuated and roads closed in avalanche-prone areas.
Though all glaciers groan and creak under stress, glaciers on an incline are especially creaky because gravity tugs on the top of the ice more than the base. Accumulating snow causes even more stress. These forces cause the glacier to fracture, sending tiny icequakes throughout. Eventually, if a glacier can't handle the stress, a large chunk will fall off, pummeling any unsuspecting villages below with a moving mass of snow and ice.
To find early warning signs of a break-off, scientists in Switzerland placed seismic instruments on a glacier precariously hugging the northeast face of the Weisshorn, a mountain in the Swiss Alps that looms over the 400 inhabitants of the village of Randa, 2,500 meters below. Break-offs in the winter are especially dangerous because the glacier has accumulated snow, so that ruptures trigger avalanches. Weisshorn avalanches have claimed 51 lives since the 17th century.
"It's the first time icequakes have been used as a precursor to these break-offs," says glaciologist Fabian Walter of the Scripps Institution of Oceanography in La Jolla, Calif.
Icequakes are less complicated to study than earthquakes because waves travel through only one medium, as opposed to several layers of the Earth. But just as scientists haven't figured out how to predict earthquakes, predicting icequakes isn't possible either.