Avalanches an Avoidable Hazard in Alaska
On March 21, 1999, Jill Fredston woke to a beautiful sunny day on the hillside above Anchorage. After rising from bed, she checked her backpack for its beacon, shovel, and snow probe. Then, she made a bag lunch and waited.
The phone call came in late afternoon.
"We've got an avalanche at Turnagain Pass," the trooper said.
Several snowmachiners were missing, and they needed a rescue team.
Fredston and her partner Doug Fesler, directors of the Alaska Mountain Safety Center, knew the March day had all the ingredients for disaster-a fresh, heavy snowfall that coated an older, weaker layer of snow, and sunshine and warmth to lure people into the mountains. By the end of the day, searchers shoveled out the bodies of two snowmachiners, the first of six fatalities.
Recovering the bodies of people suffocated by snow is a normal part of the job for Fredston and Fesler, the foremost avalanche experts in Alaska. Fredston traveled to Fairbanks recently to give a free workshop on avalanches sponsored by two area snowmachine clubs. Her winters are never boring. The weekend before she arrived in Fairbanks, Fredston knelt on chunks of snow about 80 miles east of Palmer, at the site of another massive avalanche that killed two snowmachiners.
Per capita, Alaskans are the most likely to die by avalanche. Until recently, mountain climbers and backcountry skiers were the top avalanche victims, but, during the 1990s, snowmachiners climbed to No. 1.
"Snowmachiners have the odds stacked against them," Fredston said, citing the power of new machines and the inexperience of some users. "They can get into trouble pretty fast."
That trouble often follows the script of Turnagain Pass in 1999, where snowmachiners playing a game called highmarking disturbed the fragile bond between snow layers on a steep slope. When highmarking, snowmachiners make a run straight up a mountain slope until they can get no higher, at which time they turn 180 degrees and head back down the slope. Though highmarkers often deserve the blame for triggering avalanches, a 600-pound snowmachine is not required. A jump-turn by a skier, a powder landing by a snowboarder, or the footfall of a mountaineer can be enough to displace the few grains of cohesive snow required to start an avalanche.
Avalanches come in four varieties: loose snow slides, which often are caused by warm weather; the breaking and falling of cornices, which are curls of snow formed on ridgetops; the collapse of unstable ice blocks from a glacier; and the sudden release of snow in slabs, the most dangerous type.
"This is the beast that kills people," Fredston said of slab avalanches. During a trip to the mountains east of Palmer, Fredston and other searchers stumbled around slabs as large as dump trucks. These blocks of snow came from a fracture line on the mountains that ranged from 18 inches to 15 feet thick and 3,000 feet wide. However, slabs don't need to be as large as dump trucks to be dangerous. The trouble begins when a weak layer of snow exists beneath a slab.
Slope angle is another key avalanche ingredient. The steeper the angle of the slope, the greater the stress on the snowpack. Hills rising at 35-45 degrees-nice slopes upon which to carve a few turns-are most prone to avalanches.
"The slopes we like to play on are the slopes that cause avalanches," Fredston said.
Fredston's workshop made me squirm as I watched videos of violent waterfalls of snow burying skiers and snowmachiners, but I learned about the nature of avalanches. After the workshop, she told the 60 participants that the odds of avoiding an avalanche are good if one enters the backcountry with awareness and humility.
"Don't be afraid to go out there," she said. "Forty people in the U.S. die in avalanches a year. Three-thousand die by choking on meat."