The death of snowboarder Michael Kazanjy on the slopes of Jackson Hole Mountain Resort in Wyoming on Thursday was the latest example of how out-of-bounds boarding or skiing can trigger deadly avalanches.
Kazanjy, 29, was beginning a downhill descent at the top of a snowy, back country trail not groomed or regulated by the resort. He was among thousands of other skiers who will venture into back country territory across the U.S. this winter, seeking less crowded and more exciting terrain.
Kazanjy and his five friends triggered an avalanche on their way down the mountain, setting off a huge slide of snow, according to officials, and Kazanjy was buried. By the time his fellow skiers dug him out, he was dead.
Each year an average of 28 people die in avalanches in the U.S., according to the Colorado Avalanche Information Center. Many of the avalanches are caused by the humans they end up killing, according to Jaime Musnicki, executive director of the American Avalanche Association.
"Sometimes they happen naturally and sometimes they are triggered by humans," Musnicki said, but "statistically most avalanche fatalities were triggered by the victim or somebody in the victim's party."
Musnicki said fatal avalanches are more likely to occur outside the traditional boundaries of a ski resort, in what's known as back-country or out of bounds terrain.
Many snow resorts around the country use explosives after fresh snowfall to try and manually trigger avalanches to make them safe for skiing, according to Dave Byrd, director of Risk and Regulatory Affairs at the National Ski Areas Association.
"A lot of ski areas have old World War II howitzers they use to launch explosives. Many use hand explosives that they throw to try and dislodge some of the accumulated snow to trigger a slide in advance so it's not triggered by someone skiing, which it sounds like happened here," Byrd said of the avalanche at Jackson Hole that killed Kazanjy.
Experts are still studying what exactly leads snow to suddenly slide down the face of a mountain.
"Basically what it is happening is the load, or the amount of weight on the snowpack has exceeded the strength of the snowpack and that is called a trigger or initiation. That could be one more snow flake falling onto a particular slope or it could be a human on skis or a snow machine going onto a particular slope," Mesnicki said.
"A lot of different things play into it," Byrd said. "If there's an early season storm in October that creates one layer. And then a later storm in the season in November or December, there's a different layer on top of it."
Byrd said that fresh snow on top of hard packed old snow that is "effectively ice that can allow it to slide."
Byrd said that snow slides that occur outside of resort boundaries can still shift snow enough to cause an avalanche within a ski area.
According to National Geographic, avalanches are most common within 24 hours after a snowstorm when 12 inches or more of fresh snows falls onto existing packed snow. The mix of fresh snow on old packed snow can be treacherous, and once disturbed can fly downhill at 80 mph.
Back country skiers and snowboarders are advised to carry avalanche beacons that emit radio waves in case they are buried beneath the snow in order to alert rescuers who can dig them out.
In a statement released overnight, Kazanjy's brother said, "Mike lived life with a full heart for those around him, and they for him. He loved his family, his Cal Bears, his skiing buddies and San Francisco. My parents were lucky enough to spend this Christmas with Mike in Jackson this past week, and are grateful for it. This tragic loss at a time of year when families draw close to each other is a reminder to cherish the time we have with our loved ones. Reach out to yours and tell them you love them."