Avalanche

AVALANCHE

An Avalanche (snowslide) is natural disaster ,in which a rapid flow of snow down a hill, terrain and mountainside. Although avalanches can occur on any slope given the right conditio-ns, certain times of the year and certain locations are naturally more dangerous than others.However, avalanche fatalities have been recorded for every month of the year,after snowfalls...

Fig:Incident took place at Khardung La Pass in Ladakh,jamu kashmir,india.

• When the snow breaks apart from the mountain, it begins to accelerate downhill and picks up other material along the way. 

• A fully developed snow av uralanche can travel as fast as 320 kilometer per hour.
• Which can be deadly because of their intensity and seeming unpredictability.

Death due to avalanche disaster:-

People who trapped in an avalanche are die from problems such as suffocation, hypothermia, or trauma.

• Globally, avalanche kills more than 200 people on average each year.
• On an average, 20 people die every year due to avalanches in the mountainous region of India.
• Similarly, avalanches cause an average of 30 deaths per year in the United States.

Formation of avalanche:-

• Most avalanches occur spontaneously during storms under increasing snow loads (potential) due to snowfall and erosion.
• Natural causes include rain, earthquakes, stone pelting and snowfall. The second largest cause of natural avalanches is snow changes such as melting due to solar radiation.
• Avalanche artificial triggers include skiers, snowmobiles, and controlled explosive work.
• Contrary to popular belief, avalanches do not start with a loud sound;  Pressure from sound is too low a magnitude to trigger an avalanche.

Warning systems:- 

This can be detect before avalanches take place, because in initial period move very slow. such as snowfalls avalanches caused by icefalls from glaciers. 

By using Interferometric Radars, high-resolution Cameras, or motion sensors can monitor instable areas over a long term, lasting from days to years. Experts interpret the recorded data and are able to recognize upcoming ruptures in order to initiate appropriate measures.

In modern radar technology enables the monitoring of large areas and the localization of avalanches at any weather condition, by day or night. 

Complex alarm systems are able to detect avalanches within a short time in order to close. 

An example of such a system is installed on the only access road of Zermatt in Switzerland.Two radars monitor the slope of a mountain above the road. The system automatically closes the road by activating several barriers and traffic lights within seconds such that no people are harmed.

Classification:-

There are two main types of snow avalanches. 

• Stuffs avalanche and
• Slabs avalanche.

Sluff avalanches occur when the weak layer of a snowpack is on the top. A sluff is a small slide of dry, powdery snow that moves as a formless mass. Sluffs are much less dangerous than slab avalanches.

The largest avalanches form turbulent suspension currents known as powder snow avalanches or mixed avalanches.

These consist of a powder cloud, which overlies a dense avalanche.

They can form from any type of snow or initiation mechanism, but usually occur with fresh dry powder. 

They can exceed speeds of 320 kilometres per hour and masses of 05 to 15 million tonnes; their flows can travel long distances along flat valley bottom and even uphill for short distances.

Slab avalanches:-

Slab or block avalanche are the most dangerous type of avalanche. They are the largest source of winter hazards, and most are triggered by the victims.

Slab avalanche is caused by repeated snow accumulation or re-deposition by wind.

They are characterized by fractures of blocks or slab ice severed from their surroundings.

Elements of slab avalanche include the following: -

• A crown fracture at the top of the start zone,
• Fracture fracture along the edges of the start zone, and
• A fracture at the bottom called a stitchwall. 

Crowns and flank fractures are vertical walls in ice, which destroy ice in ice that is entangled in an avalanche by ice on the slope.

Slab avalanches can vary in thickness from a few centimeters to a few meters.

A recent avalanche incident, which took place at Khardung La Pass in Ladakh (India), July 2020.

The army searched and rescued after the avalanche hit the trucks.

Army aviation helicopters were also pressed into service.

Officials said at least five-six people were killed.

Soldiers stationed in South Pullu and North Pullu were also taken to the incident site.  Simultaneously, an army helicopter was put into service to move a highly trained avalanche rescue team called the Army's "Avalanche Panthers Teams" from Siachen Base Camp and North Pullu.

These teams are equipped with specialized avalanche rescue equipment, medical equipment and avalanche rescue dogs, which are being used in search and rescue operations.  

Army aviation helicopters were also used to move deep search radars that can detect humans through ice.

The bodies of four of the 10-12 civilians buried under the avalanche have been recovered.