Avalanche!
If a scientist stands in the way of 150 tons of snow crashing down a mountain at 50 mph, can he figure out why it let loose and when it will again?
SNOW STRIKE An avalanche rumbles toward the Swiss ski resort of Evolene on February 22, 1999. A catastrophic slide the day before killed nine people. |
When all is ready, one of the men will ski to the top of the ridge, hoist four pounds of explosives on a pulley out over the crown of the slope, and light the fuse, sending vast amounts of snow down on his colleagues’ heads. If you want to understand the dynamics of avalanches, these men reason, what better place than smack dab in the middle of one?
In the weeks leading up to this event, I have been in the Swiss Alps, because the best way to learn about avalanches is to pay a visit to the very impressive, very modern Swiss Federal Institute for Snow and Avalanche Research (SLF), located in a small ski resort town called Davos. Switzerland spends $2.5 million a year on avalanche research. The architect who designed the raised-marble snow crystal motif on the lobby floor probably got paid more than Bob Brown’s entire budget for 1999. But the Swiss have a compelling reason to spend this kind of money on understanding avalanches: More than 50 percent of them live in avalanche terrain. In the 1998-1999 season, hundreds of major avalanches hit the Swiss Alps, causing more than $100 million in damages and killing 36 people. It was the most destructive season in more than 45 years.
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SETTING OFF A SLIDE A sign warns skiers away from an avalanche area studied by students and faculty at Montana State University. TK and TK create a path that will direct an avalanche toward the team’s test equipment. | |
Engineer Bob Brown (top) asembles PVC pipes that contain temperature sensors. Ed Adams (bottom) selects two 2-pound TNT charges to set off an avalanch for study. |
Issler stands beside a 10-foot-long Lucite tube containing water and dandruff-sized polystyrene particles. It’s essentially a big, long, banana-shaped snow dome. When Issler presses a button, a sliding door will retreat, sending the particles plunging down the slope, roiling and billowing into a tabletop-scale avalanche.
Issler presses the button, then peers up into the top of the tube. “Hmm,” he mutters. He thumps the Lucite with the heel of his hand. “The person who was in charge of cleaning it has retired,” he says. Finally, his captive avalanche plunges to life. “See, there’s the powder cloud.” A major avalanche—one that runs for 1,000 feet or more—will develop a towering cloud of agitated, airborne snow crystals that rides along above the tumbling snow.
No puff of air in your face, this cloud. This one kills. It snaps conifers like matchsticks and turns vacation chalets into kindling. While the snow portion or “dense flow” of an avalanche will typically stop when it hits an uphill grade, a powder cloud often rushes on, ushering mayhem up and over the top of the hill. The largest powder cloud Issler ever studied was a quarter of a mile high; its 100,000-ton mass traveled three miles before halting.








