Avalanches are most likely to happen after a heavy snow storm that drops at least 12 inches of new snow on top of old snow. Take the FREE & fun all about Avalanche quiz and download FREE worksheet all about Avalanche for kids.
While avalanches are sudden, the warning signs are almost always numerous before they let loose. Avalanches can occur without warning, sending thousands of tons of debris and ice downhill at breakneck speeds.
Feel the power of the mountain as you set an avalanche in motion and learn more about the conditions that cause this unstoppable rush of snow. In the Rhone Valley of Switzerland and France, in 1720 the Galen Avalanche took 88 lives and 100 buildings.
In 1618 on September 4, The Rodi Avalanche in Switzerland ripped through an entire city burying 2,500 people alive. Instigated by blizzard conditions of wind and snow, the Lehaul Valley Avalanche in the Himalayas buried 200 people under 20 feet of snow in 1979. Leaving only 50 people alive, the avalanche in Ranrahirca, Peru happened several years before the Great Peruvian Earthquake. There are different avalanches that are categorized by the characteristics of the avalanche.
Powder snow avalanches form currents of turbulent suspension, in which they are the largest.
Avalanches happen because heavy snow fall causes layers of snow and ice underneath to become unstable.

Yet in 90 percent of avalanche incidents, the snow slides are triggered by the victim or someone in the victim's party.
They usually happen during winter or spring but movements in the glacier can cause avalanches at any given time. On what is now known as “White Friday”, the Alps witnessed a series of avalanches claiming the lives of 10,000 soldiers, none of which guessed that enemy fire or bombs would be the least of their worries. No one survived the avalanche, however, 4 people who were away returned home only to find their entire community, homes, and friends destroyed. This was the only avalanche in the Himalayas to make it to the top ten list of most dangerous avalanches in the world.
Knowing what areas are prone to certain types of avalanches can be helpful when planning to go on a ski trip or any activity involving being on a mountain with snow. If you get caught in an avalanche, ski downward fast and then go to the right or left to get out of the way. In mountainous terrain, snow slides are one of the most dangerous natural hazards to life and property because they are able to destroy almost anything in its way with an immense amount of snow at high speeds.
While rescue workers were trying to get them out, another unexpected avalanche came and wiped them out. Unfortunately, an avalanche defeated the whole purpose of the stop when it swept the trains over a 150-foot cliff. Although these types of avalanches tend to move slowly, they can still cause great damage with powerful destructive forces because of its large mass and density.
Most are snowmobilers, skiers, and snowboarders.Many avalanches are small slides of dry powdery snow that move as a formless mass.

Rain, icefall, rock fall, earthquakes trigger avalanches as well, depending on the circumstances. Loose snow avalanches usually start at the point of the slope and widens as it travels downhill, using more snow. It is always important that you pay attention to weather reports if you are planning on doing any snow activities where there is a possibility that an avalanche can occur. These avalanches can be triggered by loose snow releases, or slab releases occurring only in snow packs that are saturated by water and equilibrated isothermally to the melting point of water. Disastrous avalanches occur when massive slabs of snow break loose from a mountainside and shatter like broken glass as they race downhill. These types of avalanches usually happen towards the end of a winter season, when there is an immense amount of daytime warming.
Avalanches are most common during and in the 24 hours right after a storm that dumps 12 inches (30 centimeters) or more of fresh snow. How the layers bond often determines how easily one will weaken and cause a slide.Storminess, temperature, wind, slope steepness and orientation (the direction it faces), terrain, vegetation, and general snowpack conditions are all factors that influence whether and how a slope avalanches. Different combinations of these factors create low, moderate, considerable, and high avalanche hazards.If caught in an avalanche, try to get off the slab.

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