An avalanche is a rapid flow of snow down a slope. These powerful natural phenomena involve massive amounts of snow, sometimes mixed with ice and debris, moving at high velocities. Their destructive potential varies, from minor slides to events capable of destroying forests and villages. Understanding how avalanches cause harm is important, as they present a hazard to individuals in their path.
The Force of the Avalanche
The weight and velocity of an avalanche inflict severe blunt force trauma. Avalanches can reach speeds up to 130 kilometers per hour (80 miles per hour), creating a powerful, destructive force. This impact causes injuries like broken bones, internal organ damage, spinal injuries, and head trauma, as victims are tossed against rocks, trees, or the ground. Death can occur instantaneously, with approximately 25% of avalanche fatalities attributed to trauma. The impact pressure of flowing snow can be substantial, often ranging from 0.5 to 5.0 tons per square foot, capable of sweeping away vehicles and demolishing structures.
Oxygen Deprivation
Oxygen deprivation, or asphyxiation, is the most frequent cause of death for fully buried avalanche victims, accounting for approximately 75% of fatalities. Once snow settles around a buried person, it becomes dense and compact, similar to concrete, making chest expansion for breathing nearly impossible. Asphyxiation involves the rapid depletion of oxygen (hypoxia) and a buildup of carbon dioxide (hypercapnia) due to rebreathing exhaled air within a confined space. This physiological imbalance quickly affects the brain and vital organs, leading to loss of consciousness and, ultimately, death. Survival chances decrease rapidly after 10 to 15 minutes of complete burial, with most deaths from asphyxiation occurring within 15 to 35 minutes if no air pocket is present.
The Deadly Chill
Hypothermia, where the body loses heat faster than it produces it, also poses a threat to avalanche victims. Rapid heat loss occurs when the body is exposed to cold snow, even if not fully buried. As the body’s core temperature drops below 35°C (95°F), hypothermia progresses, leading to shivering, confusion, loss of coordination, and unconsciousness. Untreated, severe hypothermia can result in cardiac arrest as the body’s systems shut down. While asphyxiation is often the primary cause of death for buried victims, hypothermia becomes a factor for those who survive initial oxygen deprivation or are partially buried, accelerating decline. Studies suggest a burial time exceeding 180 minutes is typically required for hypothermic cardiac arrest, indicating that for shorter burials, asphyxiation is the more immediate threat.
The Interplay of Fatal Factors
Death in an avalanche is frequently a result of combined factors, though one may be dominant. The progression often begins with immediate trauma from the physical forces of moving snow, causing instantaneous injury or death. If the victim survives the initial impact and becomes fully buried, rapid asphyxiation usually follows within minutes as dense snow prevents breathing. Concurrently, hypothermia develops due to cold exposure, and its effects can worsen hypoxia and hypercapnia. For individuals who create an air pocket, delaying asphyxiation, hypothermia becomes an increasing threat over time. Multiple lethal mechanisms can converge, making survival challenging due to the rapid onset of these combined physiological stresses.