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Chris Scott couldn’t wait to try out his new snowmobile on a clear March morning in Alaska. The last few days brought fresh, wet snow to the Kenai Peninsula and hundreds of back country enthusiasts — snowboarders, skiers and snowmobilers — started out from Anchorage to get in the last few runs of the season. Out at the Turnagain Pass Recreation Area, the sky was bright blue and the air warm. The parking lot at the Pass was full beyond capacity, which meant there were more than 150 riders in the area that day.

Between noon and 2:30 p.m. two avalanches, one about a half-mile wide and four to six feet deep, released naturally. Unfortunately, they occurred behind an obstruction — a natural rise in the mountain called “the Knob” — and because of that, the two avalanches went unnoticed by most of the riders in the wide mountain valley that day. On the slopes above Scott were a group of riders who were filming a movie. The group had been highmarking — the challenge of snowmobilers to ride as high up the steep slopes as they can, turn their sleds, and ride back down without getting stuck — throughout the afternoon. Around 3:45 p.m. the group probably set off the third avalanche of the day, but, again, most riders didn’t notice it. The film group briefly talked about the dangers but opted for one more run. It was a choice that would seal the fate of six men.

DISASTER STRIKES

At 4 p.m. a half-mile-wide avalanche released. It was probably caused by one of the highmarkers, and within moments the avalanche was travelling more than 80 miles per hour, gathering debris as it roiled down the mountainside. A few moments later it was done, and 10 snowmobilers were caught: six killed, including Chris Scott, and three injured. By the end of the 1998-1999 season 48 people died in avalanches across the United State and Canada. According to Avalanche.org 24 people died in 2012-2013 and, so far, 2014-2015 has seen two deaths.

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According to the Colorado Avalanche Information Center, Colorado leads the nation in avalanche deaths with 259 between 1950 and 2013. The statistics show snowmobilers are the most likely to be killed followed by skiers and snowboarders. In Colorado, you are more likely to die in an avalanche during January and February. The age group that sees the most deaths is 21 to 30. The majority of these deaths happen in what are called slab avalanches.

ANATOMY OF AN AVALANCHE

“There are two types of avalanches: Sluff and slab. The slab avalanches tend to be the killer,” says Dr. Karl Birkeland, director of the Forest Service National Avalanche Center in Bozeman, MT. The Turnagain Pass avalanche was a slab avalanche, and a massive one at that; the entire hillside came down and pushed many of the victims into deep areas of debris. The avalanche was classified as an R-5 slide, a “major or maximum avalanche size relative to the path.”

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The questions avalanche scientists like Birkeland ask are how could an avalanche of this size form and occur. Birkeland notes there’s no one set cause of an avalanche, and in the end, it is a complicated science and there are many different pathways to an avalanche. That said, direct snowfall is the leading cause of avalanches. In order to understand a slab avalanche you can think of the snow layers like the layers in a cake. Days, maybe weeks ago, one layer of snow falls and begins to go through a weakening process. One of the most dangerous of these processes is when they layer becomes faceted snow and, according to the Forest Service National Avalanche Center, “it grows like a parasite within the snow—often out of sight—until it is too late.” This faceted snow lacks the cohesion to hold the slab above it on the hillside. Picture the faceted snow as a layer of coarse sugar sandwiched between two layers of cake. Apply a little pressure from above and the cake layer sinks into the sugar, fractures radiate out like a mirror when a rock is thrown onto it and the snow slides down hill.

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According to Birkeland, it all comes down to cohesion. New snowfall tends to be more cohesive than the layer beneath, and when that happens an avalanche is primed. The cohesive slab above the weakened layer could come from new snow or even wind. “Wind deposits snow on the lee sides of ridges and gullies. It also breaks the snow into smaller pieces and then the snow packs in, creating denser and more cohesive slab layers.”

However, snow alone won’t cause an avalanche. Birkeland notes that avalanches are most common on open slopes steeper than about 30 degrees, but an avalanche can occur on any slope angle if the conditions are right. “In some avalanche conditions, people at the bottom of the slopes can trigger the slopes above them that can come down and bury them,” Birkeland says. When it comes to geography, some landscapes are more inherently prone to avalanches than others. There’s a good reason why that clearing is devoid of any trees.

AVALANCHE CAUSES

There are avalanches that occur naturally and those that are artificially started. Natural avalanches can occur from new precipitation (rain or new snow) falling on unstable snow, wind, a sudden warming, earthquakes and ice or rock falls. Two feet of snow over two weeks is not a problem. Add two feet in two hours — either from snowfall or wind loading — and you have the recipe for an avalanche.

When it comes to weather, wind is the leading factor in causing an avalanche. The Utah Avalanche Center notes that wind can deposit snow 10 times faster than snow falling from a storm by eroding it from the upwind side obstacles and depositing it on the leeward side. This wind loading is often seen in the massive cornices that form on mountain ridges.

“LISTENING TO YOUR GUT, YOUR INSTINCTS, SERVES YOU WELL IN THE BACKCOUNTRY. PEOPLE GET IN TROUBLE WHEN THEY GET ONTO STEEP SLOPES AND DON’T STOP TO LISTEN TO THEIR GUT.”

Artificial avalanches are the ones created by human factors such as skiers, snowboarders, or snowmobilers crossing unstable ground. According to the Utah Avalanche Center, the weight of a single person “can add a tremendous stress to a buried weak layer, not in two hours, but in two tenths of a second — a very rapid change. That is why in 90 percent of avalanche accidents, the avalanche is triggered by the victim (or someone in the victim’s party).” And, despite what Hollywood might have us believe, sound does not cause an avalanche. “This is a myth,” Birkeland says, “Sound does not trigger avalanches.” We do.

Another myth surrounding avalanches is that they can strike without warning. Avalanches have clear warnings. “The best sign of unstable conditions is recent avalanche activity,” says Birkeland. Another warning that the snow around you is prime for an avalanche are “whumpfing” sounds.

Russell Hunter, a backcountry expert and educator with the Colorado Mountain School, describes the sound of the slab layer sinking into the weakened layer as large “whumpfs.” He also notes that should you see cracks propagating from your skis or snowboard, you are probably on snow that is about to give way. In order to hear these whumpfs, snowmobilers will have to get off their machines and take a walk around. These whumpfs will be unnoticeable over the sounds of the engines.

KNOW THE WARNING SIGNS

Had the snowmobilers on Turnagain Pass that day noted even these simple warning signs, things may not have been as disastrous. Two natural avalanches had occurred and a third avalanche was artificially created. The prudent thing would have been to turn around. But, even before they left their homes that day, the weather itself should have been a warning.

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Hunter cautions anyone going into the backcountry to remember, first and foremost, that avalanches could happen at any time. Before heading out, it is important to check the conditions and recognize that new fallen snow — either blown or from a storm — is a recipe for disaster.

“IT GROWS LIKE A PARASITE WITHIN THE SNOW— OFTEN OUT OF SIGHT—UNTIL IT IS TOO LATE.”

“Listening to your gut, your instincts, serves you well in the backcountry. People get in trouble when the get onto steep slopes and don’t stop to listen to their gut.”

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But none of these pieces of advice should be taken as perfect. All the experts agree the best thing you can do to stay safe in the backcountry is to receive training from professionals at a reputable school. According to Hunter, one of the most dangerous things anyone could do is think that since they just got an avalanche beacon or a snow shovel as a gift they are going to be fine in the backcountry. If you are not trained to use the tools appropriately, or if the people in your group are not trained, the consequences could be lethal.

“There are no second chances,” Hunter says. “I would never recommend that someone go into the backcountry without training,” Birkeland adds. In order to keep yourself and the people in your group safe, there are a few things that can be done to mitigate the chances of being caught in or causing an avalanche.

HOW TO SURVIVE

Get the training. This is imperative if you are going to spend any time in the mountains and backcountry, says Hunter. The snow may look soft and fun but it can also be totally unforgiving. You can find schools specializing in backcountry training, like the Colorado Mountain School, at American Avalanche Association’s education website: www.avalanche.org/education.php

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Get the forecast. Once the course(s) have been completed, Birkeland advises that before heading into the mountains you check the weather and avalanche forecasts. Many states offer detailed avalanche warning maps. The Utah Avalanche Center (http://utahavalanchecenter. org) and Colorado Avalanche Information Center (http://avalanche.state.co.us) are a few members of the American Avalanche Association’s warning group. A nationwide map for avalanche danger is available from the Association here: www.avalanche.org/ index.php. You can also find detailed maps for other states at that website.

This is also important should you decide to just go for a drive in the mountains. According to Tracy Trulove with the Colorado Department of Transportation, drivers will want to “check the Colorado Avalanche Info website for avalanche forecasts.”

Judge your surroundings. Look for recent avalanche activity and keep your eyes and ears open. Remember, the majority of avalanches occur on slopes between 35 and 45 degrees, and seldomly occur on slopes less than 30. Slopes steeper than 50 degrees tend to sluff — a small, loose snow avalanche — often and do not build the slabs that create danger. Unfortunately, a 35-degree slope is exactly the type of slope that lures skiers, snowboarders, and snowmobilers into the backcountry. According to the Utah Avalanche Center, black diamond runs at our favorite ski resorts are usually 35 degrees. If your group finds itself on these slopes, be sure to only have one person go at a time and never park or rest at the base of these slopes.

When driving, Trulove advises that though “CDOT’s avalanche mitigation process protects our customers as best we can north facing slopes with 30 degrees open terrain with little or no vegetation” can still pose as risk factors while driving through the high country. In Colorado, CDOT has two phases of avalanche mitigation: 1. During the winter they will utilize explosives to clear dangerous areas, and 2. During the summer months they will review the terrain and do maintenance on snow fences.

Get the gear. Birkeland urges that, “at minimum, everyone in the party should have a probe, a shovel and an avalanche beacon.” And be sure that everyone knows how to use these tools. One of the first things Hunter teaches his students in an avalanche rescue is to put eyes on everyone else’s beacon to be absolutely certain everyone’s beacon is on search mode and not transmit. He says that if one person in the search party is still transmitting, then the rescue efforts will go in circles. And that is time that the victim can ill afford. Trulove suggests drivers “be proactive and travel into the mountains with extra blankets and water and some kind of food and even a candle or two.”

WHAT TO DO IF CAUGHT IN AN AVALANCHE

Even if your group has done everything right an avalanche could still catch you. What now?

If you happen to be caught in an avalanche while in your car, “if possible stay in your vehicle with your seat belt on call for help with a cell phone and wait for emergency response,” Trulove says. But most of all don’t panic. “The sound of the avalanche will be terrifying,” Hunter says. And he should know, he was caught himself in a smaller one. “It will almost sound like a shotgun, other times it may sound like a deep muffled thunk that grows louder as the snow picks up speed. Instinctually, you immediately know something is wrong and you feel helpless. But you cannot panic.”

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“The first thing,” Hunter tells his students, “is to get yourself off the moving snow. Try to grab a tree, ski or ride your machine to the side.” But this is as hard as you might imagine. After four seconds the slab you are on will be travelling 40 miles per hour. It will reach speeds up of to 80 miles per hour and would be difficult to outrun even on a snowmobile. If you are unable to get off the slab you should begin swimming. Because the avalanche debris is 60-70 percent air the human body will be three times denser than the surrounding snow. If you don’t try to swim, you will quickly sink to the bottom.

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“The best thing you can do is to remain calm,” Hunter says. A person’s greatest chance of survival does not come when the avalanche is done, but just before it stops. As it slows it is imperative that you are able to clear as large a space in front of your face as possible. Despite the snow being 60-70 percent air, once an avalanche has stopped, it will set like concrete. People die in avalanches because of carbon dioxide poisoning but being able to create a large enough void for air before the snow sets will determine your ability to survive. Birkeland says, “The big danger from the snow is being asphyxiated. But you can also just get beat up in a big slide as you get tossed around. It can be pretty random. Sometimes people will get killed in small slides and occasionally people caught in large slides will survive.” According to the Utah Avalanche Center, “93 percent of avalanche victims can be recovered alive if they are dug out within the first 15 minutes, but then the numbers drop catastrophically. After 45 minutes, only 20-30 percent are still alive and after two hours almost no one is alive. In other words, you don’t have much time.”

“93 PERCENT OF AVALANCHE VICTIMS CAN BE RECOVERED ALIVE IF THEY ARE DUG OUT WITHIN THE FIRST 15 MINUTES, BUT THEN THE NUMBERS DROP CATASTROPHICALLY.”

Your best chances are within those first fifteen minutes and Hunter advises that “you relax and conserve your breath. Know that your trained partners are looking for you.”

The “relax advice” goes for those in the search party, also. “Even in our avalanche classes, the adrenaline in the search party is insane,” Hunter says. If it is your best friend beneath the snow, you may be feeling panic, anxiety, or fear, but “it may be in their best interest for you to take a quick break to focus,” Hunter adds.

BE THE RESCUER

Before you head out into the avalanche debris the first thing you need to do is assess the situation. Hunter recommends you check to see if another slide is possible. Hopefully, you were able to watch the person caught and pinpoint the spot you last saw them. Once it is safe, figure out how many in your group are buried. Switch your beacons to search and begin a search. If you are by yourself, you should work your way up the slope in an S-shape keeping 30m between your pass across the slope. There are other techniques for larger groups that are taught exhaustively in the courses.

However, if you happen to be one of the many people who are caught in the backcountry without the proper equipment, there is still hope. Hunter suggests you look for visual clues such as gloves, boots, skis, or parts of a snowmobile. Pull on everything. Direct your search to possible burial spots such as a cluster of trees, a depression in the snow where people are often deposited if they are not able to swim, or along the outside of any turns that the avalanche may have taken. Use your ski pole or even a tree branch as a probe.

If there are multiple burials, take care of the shallow ones first. Get them breathing but do not work to dig them out yet. Move to the next shallowest and work your way until you have reached all the trapped members of your group. Once everyone is able to breath then dig each one out and begin first aid.

As winter beckons and we are tempted to test our mettle against the best nature can throw at us, it is prudent to realize nature always holds the trump card and we must be both cautious and vigilant when playing in our snowy backyards. The snow that looks too perfect without a long swooping track from our skis could be hiding a killer beneath, silently lurking and waiting for the slightest pressure to spring forward. But with knowledge, the right tools and careful planning that killer can be managed.

 

Editors Note: A version of this article first appeared in the March 2015 print issue of American Survival Guide.