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RSTV: IN DEPTH – AVALANCHE


RSTV: IN DEPTH – AVALANCHE


Introduction:

            In the Kargil district, the Indian Army has another big adversary besides Pakistan . These are avalanches. Over 1,000 Indian soldiers, including over 35 officers, have lost their lives in the Siachen Glacier-Saltoro Ridge region since April 1984.On Monday, four soldiers died after being trapped in snow for hours after an avalanche hit Army positions in northern Siachen Glacier. Two porters also died. The soldiers were a part of a patrolling group of eight. At a height of around 20,000 ft in the Karakoram range. The Siachen Glacier is known as the highest militarised zone in the world where the soldiers have to battle frostbite and high winds. 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.

 

Prediction and protective measures:

  • In order to reduce fatalities and to protect villages and roads, people attempt to predict and prevent avalanches.
  • Accurate avalanche prediction requires an experienced avalanche forecaster who often works both in the field to gather snowpack information and in the office with sophisticated tools such as remotely accessed weather data, detailed historical weather and avalanche databases, weather models, and avalanche-forecasting models.
  • Avalanche detention wall.
  • Avalanche forecasters combine their historical knowledge of past conditions with their knowledge of the affected terrain, current weather, and current snowpack conditions to predict when and where avalanches are most likely to occur.
  • Avalanche mitigation wall.
  • Such forecasting work typically takes place along mountain highways, adjacent to potentially affected villages, at ski areas, and in terrain heavily used for backcountry skiing and snowmobiling.
  • In addition to predicting avalanches, people employ a variety of techniques to reduce avalanche danger. Explosives are used to trigger avalanches on potentially unstable slopes so that the avalanches will occur when people are not endangered.
  • Such avalanche control is particularly effective for ski areas and highway corridors.
  • In some areas prone to avalanches, particularly near villages and fixed structures, devices such as avalanche rakes (large reinforced fencing) are used on slopes to hold snow in place, and diversion structures such as dams or wedges are used at the base of the slope to stop, split, or deflect the snow in an avalanche.
  • Though expensive, these defensive measures are common throughout the Alps, where numerous villages are found in areas known for dangerous avalanches.

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