Large mass of rock debris or snow that moves rapidly down a mountain slope, sweeping and grinding everything in its path.

An avalanche begins when a mass of material overcomes frictional resistance of the sloping surface, often after its foundation is loosened by spring rains or is rapidly melted by warm, dry wind. Vibrations caused by loud noises, such as artillery, thunder, or blasting can create an avalanche.

Avalanches usually occur in February, March, and January. They can also occur in April when everything thaws.

There are three different types of avalanches…..

1. A dry snow avalanche consists of powdery snow and air that can move faster than 100 MPH.

2. A wet snow avalanche is a mass of partially melted snow that moves slower than a dry snow avalanche.

3. A slab avalanche is when a portion of snow breaks loose as a slab and splits into pieces as it slides.

Avalanches can occur anywhere in the world.

They occur where ever there is a high snow covered mountain.

Avalanches can also occur near plate boundaries. Usually at convergent plate boundaries.

Avalanches don’t do a lot of damage to cities or towns because they are up in the high mountains but anything up there better watch out. Avalanches burry mountain side homes and destroy forests. They also take down radio towers and lodges that are in its path. Avalanches also take away people’s lives, especially skiers who are taking a trip down the mountain.

These are three different ways that an avalanche can start.

Avalanches cause a fair amount of deaths when they occur. They are so hard to predict and because of that people never know when they are going to happen. That is why it is best to never go onto a mountain alone.

If caught in an avalanche….

Yell and let go of ski poles and get out of your pack to make yourself lighter.

Use "swimming" motions, thrusting upward to try to stay near the surface of the snow.

Above all, do not panic. Keeping your breathing steady will help preserve your air space and extend your survival chances. If you remain calm, your body will be better able to conserve energy.

If you are in over your head (not near the surface), try to maintain an air pocket in front of your face using your hands and arms, punching into the snow.

When the avalanche comes to a stop try and and dig your way up to the surface if you know you are close.

If you are in an area that is highly at risk for avalanches be sure not to ski or use any snowmobiles on the mountain.

Try not to use any explosives around an avalanche zone.

If there was a heavy snow fall the night before make sure not to go on the mountain because you might trigger an avalanche.

Don’t ever go alone on a mountain that has been known to have avalanches.

To prevent avalanches they build up snow fences to prevent buildup of snow in the starting-zones. Also defecting walls are built up to divert avalanche flows away from buildings and even entire towns. Sheds are also build across roadways that pass through persistent avalanche paths and they can help to protect motorists from avalanches. Slopes with trees help to prevent avalanches as well. They use explosives to set off small avalanches in areas that are of potential danger. This is to reduce the size of future avalanches in the risk area.

There isn't really such thing as an avalanche warning because you can’t give a warning for an avalanche. Avalanches don’t happen over a period of time like other natural hazards do. They happen because of vibrations and heavy snow fall so you can’t really say when they are going to happen until they actually do.

They are doing research to find out about the mechanisms that govern the build-up of snow - wind and precipitation - instability within the snow cover, and the flow of avalanches.

The main objective of this research is to improve zoning and make defences more effective and more reliable.

This is an avalanche dog.

Avalanche dogs are used after an avalanche has occurred. They sniff through the snow to try and find any people that might be buried underneath.

Internet

http://europa.eu.int/comm/research/success/en/env/0338e.html.

http://geography.about.com/library/weekly/aa022299.htm

http://nsidc.org/snow/avalanche/

http://www.climbersguide.com/training/avalanche.html

http://www.cln.org/themes/avalanches.html

http://www.csac.org/Incidents/2002-03/20030307-India.html

http://www.geo.mtu.edu/department/classes/ge404/avalanche/control.html

http://www.natives.co.uk/news/2002/1202/12aval.htm