Avalanches, Types, Key Features, Prevention and Safety

What are Avalanches?

• An avalanche is a rapid flow of snow down a slope, such as a hill or mountain.
• Causes: Avalanches can be triggered by wind, rain, warming temperatures, heavy snowfall, earthquakes and human activity  such as snow sports and vibration etc.

Types of Avalanches

• Slab avalanches made of tightly packed snow, triggered by a collapse of an underlying weak snow layer.
• Sluff avalanches occur when the weak layer of a snowpack is on the top (Sluffs are less dangerous than slab  avalanches).
• Cornices are overhanging masses of wind-deposited snow that protrude from sharp terrain features like ridges or peaks.
• Powder snow avalanches where snow grains are largely or completely suspended and moved by air in a state of fluid

Key Features of Avalanches

Trigger Factors

• Natural triggers: Heavy snowfall, rapid warming, rain, earthquakes, or wind-loading of snow.
• Human activities: Skiers, snowboarders, climbers, or explosives used in snow management.

Avalanche Path

• Starting Zone: Where the avalanche begins, often steep and snow-laden.
• Track: The path the avalanche follows downhill.
• Runout Zone: Where the avalanche slows and comes to a stop.

Causes of Instability

• Weak snowpack layers.
• Rapid temperature changes.
• Overloading of snow layers due to precipitation or wind.

Impacts

• Loss of life and injuries to people in its path.
• Damage to property, infrastructure, and the environment.
• Disruption to travel and tourism in mountainous regions.

Avalanche Prevention and Safety

• Monitoring and Forecasting: Using technology and weather data to predict avalanche risks.
• Control Measures: Artificial triggering using explosives or barriers to redirect avalanches.
• Personal Safety:
  • Carrying avalanche safety gear (beacons, probes, shovels).
  • Checking avalanche forecasts before venturing into risky areas.
  • Training in avalanche safety and rescue techniques.

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