Sikkim: What causes Avalanche and how to prevent them

An avalanche striked near the Nathu la border area, Sikkim yesterday. So far, 7 tourist have died and several are feared missing. Rescue teams rushed to the location immediately but thick snowfall and bad weather made the access to the area difficult and slowdown the rescue operation.

Avalanches occurs when a layer of snow collapses and slides downhill. It is primarily caused by four factors - a steep slope, snow cover, a weak layer in the snow cover and a trigger.

Causes of Avalanche

1) Snowstorm and Wind Direction
Heavy snowstorms are more likely to cause Avalanches. Wind normally blows from one side of the slope of mountain to another side.

2) Heavy snowfall
Heavy snowfall deposits snow in unstable areas and puts pressure on the snow-pack. Precipitation during summers is the leading cause of wet snow avalanches

3) Human Activity
Winter sports that require steep slopes put pressure on the snow which it can deal. This is one of the major contributor of many avalanches in recent years.

4) Vibration or Movement
The use of All Terrain Vehicles(ATV) and Snowmobiles creates vibrations within the snow that it cannot withstand. Coupled with the gravitational pull, it is one of the quickest ways to cause an avalanche.

5) Layers of Snow
When fresh snow falls on the old snow which has alreasy turned into ice, it can cause the fresh snow to easily slide down.

6)Steep Slopes
Layers of snow buildup in steep areas can easily slide down the snow, causing an avalanche.

7) Warm temperatures
Warm temperatures that can last several hours a day can weaken some of the upper layers of snow and cause it to slide down.

Prevention
Experts suggest a mix of natural and artificial measures to prevent avalanches.

Planting flora and fauna in hilly areas to stabilise the soil, creating snow fences and barriers to keep snow away from vulnerable areas is the man-made solution for avalanche.

Using explosives to jar loose small buildups of snow helps in preventing buildups that could lead to large, devastating avalanches.