Tuesday, July 15, 2008

Avalanches: Not All Their Cracked Up to Be

Skiers recently gained useful, (possibly life-saving) new knowledge about the causes of avalanches, thanks to a new study by physicists at the University of Edinburgh in Scotland.

According to the authors, the particular ways that snow cracks and collapses is a telltale sign of avalanche formation. Certain crack patterns can foreshadow whether or not a slab of snow will cascade down the slope in a tumbling mass of disaster, or simply collapse onto itself.

This means that contrary to popular belief, crack sizes don't necessarily increase as the slope angle decreases. Rather, snow slides can happen at any slope angle, there is no is minimum requirement.

Researchers modeled the most common type of avalanche, known as slab avalanches, where a giant chunk of snow breaks off and meets its fate at the foot of a mountain. They found that compression, or how packed the snow is, plays a greater role in avalanche dynamics than gravity pulling down along the slope does.

By investigating the structure of snow layers, which are comprised of hollowed-out ice grains that form cavities, researchers determined that patterned cracks in the snow can spread over large areas, triggering avalanches.



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