Science: The White Death

Even as rescuers were searching for the victims of Europe's latest avalanches (see THE WORLD), scientists atop an Alpine mountain were continuing the work that may some day prevent such disasters. They are members of Switzerland's Federal Institute for Snow and Avalanche Research, the world's first and foremost scientific establishment dedicated to the study and forecasting of avalanches. Before the institute was established 26 years ago, high above the resort town of Davos in the eternal snows of the 8,000-ft. Weissfluhjoch, knowledge of avalanches consisted mostly of folklore. Now, thanks to the institute's physicists, crystallographers, engineers and foresters, science has come closer to understanding the mysterious mechanisms that tumble torrents of snow down the mountainsides.

Jagged Beauty. At the core of all avalanche research is snow itself. Often hexagonal-shaped, the tiny crystals that make up snowflakes are as exquisitely formed as the finest man-made jewelry. As the crystals alter their beautiful structure under the influence of wind, temperature change, icy vapors and the weight of fresh snow, they may lose their ability to interlock. They degenerate into coarser, larger crystals and sometimes even into lumps of ice. Such "old" snow cannot maintain a good grip on the soil or underlying layers of snow. The slightest disturbance may tear it free: the sonic boom of a passing aircraft, the stresses created by a pair of skis

even a loud shout by a solitary skier.

As a result of their studies, Avalanchologist Andre Roche and other institute scientists now classify avalanches in two basic groups. One is the dreaded Staublawine (German for dust avalanche), which may occur, for example, when heavy new snowfalls fail to cling to the older foundation and begin to slide in billowing masses down the slope. It can be set off by a sudden shift of wind. Literally riding on a cushion of air at speeds of up to 150 m.p.h., dust avalanches create such enormous pressure differentials that they have been known to pull people out of their homes or knock down scores of trees without actually striking them.

An even more destructive phenomenon is the giant slab avalanche, or Schneebrett (snow board), in which a huge mass of snow may come sliding down, as at Reckingen in Switzerland last week. Highly unpredictable, slab avalanches occur when one cohesive layer of snow breaks free of the ground or of other snow layers. They can be caused by rising temperatures that send lubricating water between layers of snow, letting the white blanket slip like a quilt from the bed of a tossing sleeper. Exerting forces as great as 100 tons per square yard, such avalanches have been known to upend steel locomotives, push small bridges hundreds of feet from their pilings and rip up vast reaches of forest.