By Jonny Lupsha, Wondrium Staff Writer
Every year, an estimated one million avalanches fall globally. These powerful slides of masses of snow can exceed 100 miles per hour. One may have caused a mysterious Russian tragedy.
For 60 years, the world has wondered what caused the so-called “Dyatlov Pass Incident,” in which nine experienced hikers were found dead and only partially clothed in Russia’s freezing Ural Mountains. Wild speculation from the public has blamed everything from yeti to UFOs, but new evidence suggests an avalanche may be the culprit.
A sudden avalanche would explain why some of the hikers were found only partially clothed—since they can exceed 100 miles per hour, there would be little time to dress if one wished to escape being buried.
Avalanches are caused by any number of wintry conditions on a mountain, claiming about 150 lives per year. In his video series The Science of Extreme Weather, Professor Eric Snodgrass, Director of Undergraduate Studies for the Department of Atmospheric Sciences at the University of Illinois at Urbana–Champaign, explained how these mighty phenomena work.
Types of Avalanches
“Avalanches occur when large masses of snow slide down a mountain,” Professor Snodgrass said. “They can be triggered by winds, but avalanches can also be due merely to heavy snowfall, shifting snow, or a thaw/freeze cycle. Worldwide, there are an estimated one million avalanches per year.”
According to Professor Snodgrass, snow conditions dictate the type of avalanche. One comes from powdery snowfall; as feet of snow pile up, the additional snowfall becomes unstable and slides down the mountain, making it appear as though the air is full of a white dust.
“Midwinter thaws can create a different type of avalanche called the slab avalanche,” he said. “The top few inches of snow may melt when warmer air spreads over the mountain during the fall. When the temperatures fall again, the melted snow refreezes as a sheet of ice.
“New snow that falls has a difficult time bonding with the ice surface [so] additional snow will pile up and suddenly slide all at once down the mountain as a huge slab.”
A Necessary Danger
Many roads in the United States, including some highways and interstates, cross snowy mountains. Avalanches can shut down these roads for days or even weeks at a time, stranding drivers while the snow is cleared from the roads. However, it’s a small price to pay.
“Despite the risks and potential life-threatening hazards, the West needs this snow,” Professor Snodgrass said. “Snowpack is crucial for supplying melt water to fill the Colorado and Columbia Rivers. These two rivers supply drinking water for millions and their tributaries are used intensively for irrigation.”
He also said that the West Coast relies on melt water to power hydroelectric generators. Nearly 80% of Washington state’s electricity comes from hydroelectric power stations, as well. But ultimately, it all starts with atmosphere “rivers,” jet streams named so for the amount of moisture they carry.
“Mount Rainier is often the first large obstacle atmospheric rivers encounter,” Professor Snodgrass said. “Given its enormity and the 14,400 foot elevation, this [area] can receive 10 to 15 feet of snow every time it finds itself in the target of this persistent flow. When this occurs, there’s a high risk for avalanche.”