Relevance: Mains: G.S paper I: Geography
Avalanches and landslides are common on the glacier during the winters and temperatures can drop to as low as minus 60 degree Celsius.
Avalanche, a mass of material moving rapidly down a slope.
An avalanche is typically triggered when material on a slope breaks loose from its surroundings; this material then quickly collects and carries additional material down the slope.
There are various kinds of avalanches, including rock avalanches (which consist of large segments of shattered rock), ice avalanches (which typically occur in the vicinity of a glacier), and debris avalanches (which contain a variety of unconsolidated materials, such as loose stones and soil).
The size of a avalanche can range from a small shifting of loose snow to the displacement of enormous slabs of snow.
In a slab avalanche, the mass of descending snow may reach a speed of 130 km (80 miles) per hour and is capable of destroying forests and small villages in its path.
Avalanches kill about 150 people a year in North America and Europe. Most of those killed are backcountry skiers, climbers, snowshoers, and snowmobilers who accidentally trigger an avalanche and become buried in the snow.
Avalanches also have been triggered intentionally in warfare to kill enemy troops.
In World War I, during fighting in the Alps on the Austrian-Italian front in December 1916, more than 10,000 troops were killed in a single day by avalanches triggered by artillery fired onto slopes of unstable snow.
Features of avalanches:
Avalanches contain three main features: the starting zone, the avalanche track, and the runout zone. Avalanches launch from the starting zone. That’s often the most unstable part of the stope, and generally higher on the mountain.
Once the avalanche starts to slide, it continues down the avalanche track, the natural path it follows downhill. After avalanches, large clearings or missing chutes of trees provide clues to an avalanche’s trajectory.
The avalanche finally comes to a stop at the bottom of a slope, in the runout zone, where the snow and debris pile up.
Factors responsible for the Avalanche:
Heavy Snowfall
When a high rate of snowfall occurred leading to the snow accumulation on the mountain slopes triggered the weaker layer of snow in the snowpack of unstable areas of the mountain causes Avalanche.
- Wind Direction
The direction of the wind determines the patterns of the snowfall as well snow accumulation on the mountain slopes. If the strong wind blows, then the upward direction of the winds might trigger the steep slope which causes an avalanche.
- Layering of Snow
The gradual snowfall creates layer by layer accumulation of snow that hypersensitive the snowpack. If something catastrophic events happen then these layers of snow falls down that leads to avalanche.
- Steeper Slopes
An avalanche is also caused by the influence of gravity. If gradual snowfalls accumulated on the slopes of the mountain then it prone to rush downs the slopes at greater speeds.
- Higher Temperatures
Temperature is one of the important factors for the avalanche because of high temperature the surface layer of the snowpack gets melted. The accumulated snow will become highly susceptible to sliding down.
- Earthquakes
It is one of the important factors that triggered the layer of accumulated snowpack because earthquakes generate seismic waves that cause the ground to vibrate.
- Movements or Vibrations Produced By Machines and Explosives
As we know that the population increasing day by day, which requires development activities to meet the population requirement. During the developmental activities, the terrain vehicles in regions with unstable layers of snow can dislodge the layers from the surface and cause them to slide down under gravity.
- Deforestation
Deforestation, clearance, or clearing is the removal of a forest or stand of trees where the land is thereafter converted to a non-forest use. Trees and plants always protect land against natural disasters like floods, tidal waves, strong winds, and also avalanche. Hence, a developmental activity for economic gains makes the mountain region an avalanche-prone area more susceptible to deadlier avalanches.
- Winter Sports Activities
Above all the factors, this factor will act like the last nail to triggered steep slopes or loose snowpack by skiers or other winter sports activities.