Explained: What Is An Avalanche? Know All About The Natural Phenomenon

Beautiful snow becomes deadly when it slides down the hill at a speed as fast as 100 miles per hour compiled with ice and rocks or any matter present on the mountain slopes.

New Delhi: The morning hours in Sikkim brought bad news as the tourist hotspot was hit by a massive avalanche near the Nathu La border area on Tuesday. The avalanche hit the arterial Jawaharlal Nehru Marg, which connects Gangtok to Nathu La at the China border, around 11.30 am, trapping five-six vehicles with around 30 people under the snow, the Army said in a statement.

The natural tragedy that claimed the life of seven tourists while leaving several others injured, has raised basic questions in several people's minds - what is an avalanche? How lightweight snow can become deadly? How does the avalanche happen?

What is Avalanche?

To answer the first question- what is an avalanche - rapidly slides down, falling masses of snow ice, and rocks on mountains comprise an avalanche. When seen from a far distance, an avalanche appears to be a beautiful natural phenomenon.

However, this beauty turns into tragedy for those who are in its vicinity, and here comes the answer to your second question - how snow and ice become lethal. An avalanche is not only snow but a heavy mass comprising of rocks and hard ice along with lightweight snow that becomes life-threatening as this heavy cluster rolls down the mountain with high speed and momentum that pose threat to the life of anyone in its way or surrounding.

Reason of Avalanche

The question that still remains is why an avalanche happens. What triggers the occurrence of such deadly disasters? Superficially, it seems like an avalanche occurs due to unstable thick layers of snow rolling down the mountain slope under bad weather conditions, it seems a natural phenomenon, which it is but it is not always the case.

When we add a human component to the avalanche it becomes a deadly combination. When people try to walk over an ice slab that has a waker layer of ice lying under it then the weak layer collapses and causes the upper mass of the snow to slide which then piles up into an avalanche.

Features of Avalanche

An avalanche has three main features- starting zone, avalanche track, and runout zone. As the name suggests, starting zone of avalanches is the point from where the calamity started and generally it is the most unstable part of the slope or the steep point of the mountain. 

As the heavy masses of snow, ice and stones and other matters present on the mountain roll downhill it follows a path that is referred to as an avalanche track.

An avalanche only stops when it runs out of slope and momentum of its matter which is generally the area at the bottom of the mountain where all the debris of the disaster piles up in the end.