What is an avalanche? A list of the deadliest avalanches in the world

An avalanche is a large amount of ice, snow and rock falling quickly down the side of a mountain. It is one of the deadliest phenomena that could occur for those living at the foothills of mountains in cold regions across the world.

It is one of several natural disasters that can occur and are deadly for anyone caught in them, with a mortality rate of 25 per cent in general. The chances of someone surviving an avalanche can be greatly increased if the person is pulled out of the snow in under 10 minutes.

Here are some of the leading factors of death for avalanche victims followed by a list of five of the world’s deadliest avalanches.

Also read: Avalanche hits Uttarakhand’s Chamoli, 57 construction workers trapped

Survival and mortality rates

The window of opportunity where a person’s chances of survival are the highest (around 92 per cent) is under 15 minutes of the avalanche burying the person under snow. Then the survival rate drops significantly with time.

After 35 minutes, the survival rate drops to 30 per cent after just 35 minutes of being buried under the avalanche. If a person’s entire body is buried under the snow they have a higher likelihood of mortality, while partially buried people with their heads above the snow have a much higher chance of survival.

Primary cause of death

The primary cause of death in an avalanche is ‘asphyxia’ which is a condition when the body does not receive sufficient oxygen and begins to shut down, greatly threatening the life of an avalanche’s victim.

According to Safeback, asphyxia accounts for roughly 75 per cent of all avalanche fatalities.

A person’s entire body buried in the snow is called a ‘critical burial’ and has a 44 per cent mortality rate with a 47 per cent likelihood of it occurring for victims of an avalanche.

Also read: Himachal Pradesh: Earthquake of 3.7 magnitude hits Mandi

Burial depth matters

The burial depth also significantly affects the survival rate in asphyxia-related deaths. The chances of a victim buried 1 metre under the snow is around 90 per cent, however, for a victim 2 metres under the snow the chances drop massively to 30 per cent.

Five of the world’s deadliest avalanches

1. The 1970 Huascarán Avalanche in Yungay, Peru took 22,000 lives. The fatalities were greatly increased as the massive Ancash earthquake shook the glacier and masses of snow, resulting in the falling snow carrying debris on its path down the mountain. The debris included fragmented rock and wet soil falling down the mountain at a rapidly-progressing mudslide that destroyed Yungay and ten more villages

2. The 1916 White Friday Avalanche took between 2,000 to 10,000 lives in Marmolada, Italy. The first of the avalanche began with 100,000 tons of snow, rocks and ice that rapidly descended Mount Marmolada and went into the barracks of Austrian soldiers, taking 300 lives. More lives were subsequently lost as collective avalanches in the same region kept taking lives over and over again.

3. The 1962 Huascarian Avalanche in Peru took 4,000 lives. Residents of the towns of Ranrahirca and Huarascucho came together for dinner and heard the thundering boom of a six million ton glacier that has dislodged itself from the mountainside. The sound of the glacier allowed people to seek higher ground for safety to no avail as the towns were buried under 40 feet of snow with a speed of 15.28 kilometres in 7 minutes.

4. The 1979 Lahaul Valley Avalanche in India took 254 lives. The Lahaul Spiti Valley in Himachal Pradesh had four villages buried under an avalanche triggered by multiple snowstorms. The avalanche lasted over five days as a result of excessive snow.

5. The 2021 avalanche in Chamoli, Uttarakhand took 80 lives, with 200 reported missing. The avalanche wiped away the Rishiganga hydroelectric project and caused extensive damage to a larger project on the Dhauliganga river. This disaster has been marked as one of the most devastating tragedies of the year that led to flash floods and extensive destruction of structures and properties.

Crucial aspects in saving victims

Avalanche safety equipment like transceivers, probes and shovels act as crucial necessities to locate and extricate buried victims quickly to minimise the mortality rate due to asphyxia for the victims.