An avalanche is a rapid, turbulent flow of snow, ice, and debris moving down a slope. These events are most commonly triggered when a heavy slab of snow fractures and slides along a weaker layer in the underlying snowpack. Survival is highly dependent on preparation, a quick reaction to the slide, and the immediate, coordinated effort of companions. Understanding the physics of the slide and the narrow windows for rescue can empower individuals in avalanche terrain.
The Real Odds of Survival
The probability of surviving a full burial drops steeply after the first few minutes, making companion rescue the most important variable. Studies show that a victim rescued within the first 10 to 15 minutes has a survival rate exceeding 90%. This initial period allows the body to receive sufficient oxygen from the small air space around the face. The survival curve falls dramatically, with only about 25% to 30% of victims surviving past 35 minutes of burial time.
The leading cause of death is asphyxia, or suffocation, accounting for approximately 75% of avalanche fatalities. This occurs when the victim re-breathes carbon dioxide or the snow’s weight compresses the chest, preventing breathing. Blunt force trauma, from being thrown against trees or rocks, is the second leading cause, responsible for roughly 20% to 30% of deaths. The lack of oxygen proves fatal long before hypothermia sets in, meaning freezing is rarely the cause of death in the immediate phase.
Essential Preparation Before Entering Avalanche Terrain
Survival efforts begin well before stepping onto the slope, requiring both knowledge and specific equipment. The foundation of safety is understanding snow science, which involves recognizing unstable terrain, weather patterns, and the structure of the snowpack. Training teaches travelers how to read an avalanche forecast, which provides ratings and details on where a slide is likely. Avoiding the slide is the primary survival tactic, as most avalanche incidents are triggered by the victim or someone in their group.
Every person entering the backcountry must carry three pieces of rescue equipment: an avalanche transceiver, a probe, and a shovel. The transceiver, worn close to the body, continuously emits a radio signal to allow companions to locate a buried victim. The probe is a long, collapsible pole used to pinpoint the victim’s exact location and depth. A durable, metal-bladed shovel is then needed to move the massive volume of compacted snow.
Immediate Survival Techniques While Sliding
The moment a slide begins, the immediate goal is to stay on the surface of the moving snow and avoid being drawn deep into the flow. If possible, attempt to exit the slab by moving quickly to the side of the avalanche path, where the flow speed and volume are lower. The forces within a fast-moving avalanche are immense, as the snow acts like a dense, chaotic fluid.
If caught, the most effective technique is to utilize a vigorous “swimming” motion, aiming to stay near the top layer of the debris. This action leverages inverse segregation, which encourages less dense objects, like a human body, to rise toward the surface. Travelers should attempt to shed heavy equipment, such as skis and poles, that can drag them deeper. Keeping a backpack on can offer some protection to the back and kidneys from trauma.
As the avalanche begins to slow down, just before it sets, a final, deliberate action can improve survival chances. Use your hands to create a small air pocket directly in front of the mouth and nose. Simultaneously, reaching one arm straight up toward the snow surface may provide a directional indicator for rescuers. These actions must be performed quickly, as the moving snow rapidly decelerates and compacts.
Surviving Burial and the Critical Rescue Window
Once the snow stops moving, it instantly hardens and sets like concrete, trapping the victim in near-total immobility. The immediate survival focus shifts to conserving the limited oxygen within the created air pocket. Panic quickly depletes oxygen and increases carbon dioxide levels, accelerating the onset of asphyxia.
If completely buried, a person will likely be disoriented and unable to tell which direction is up. A simple technique to determine orientation is to spit; gravity will pull the saliva downward, indicating the correct direction to try and dig. However, movement is often impossible, and the victim’s life depends entirely on the speed of a companion rescue.
Companions must immediately switch their transceivers to search mode and begin the organized process of signal searching, probing, and strategic shoveling. The success of this rescue is directly linked to the first 15 minutes, as the survival rate drops significantly after that window closes. Victims buried deeper than 120 centimeters face higher mortality rates. Therefore, constant practice with rescue gear is necessary to ensure the process is executed with efficiency.