What is an Avalanche?

An avalanche is a fast moving flow of snow and ice that rapidly travel down a mountain slope, uprooting trees and anything in its path.

What causes and Avalanche?

Many factors cause an avalanche including the weather, the temperature, the steepness of the slope, the direction of the slope, vegetation, wind direction, terrain and the snow pack conditions. All of these factors are able to change by the hour, making an avalanche unpredictable and extremely dangerous.  An avalanche occurs when the layers of snow near the surface cannot be supported by the layers below, causing a flow of snow to move at a rapid speed down the mountainside.
    Avalanches generally happen after a snowstorm, approximately 24 hours after a significant snowfall.   As more snow accumulates, this builds more pressure on the snow, causing more stress.  The weather and temperature are also important factors, as the sun beats down on the snow, it causes melting, however colder nights cause the snow to freeze.  Warm fronts are dangerous, causing unstable temperatures and changes in the snow.   Avalanches are most likely to occur in the north, east and the northeast, because shadows are generally cast in these directions causing unstable snow conditions, and cooling and warming temperatures.

Where are they most likely to occur?

 Avalanches are most likely to occur in the alpine regions of France, Switzerland and Austria.  However avalanches can occur on any steep slope, considering the factors.  Within the U.S, Alaska, Colorado and Utah are the states that avalanches occur most often.

Interesting Facts:
-    Avalanches can reach speeds of 250 miles per hour.
-    Most avalanches occur between 30 and 45 degrees, on a slope that faces the north, east and northeast directions.
-    Mountains that are heavily forested are safer areas, where avalanches happen the least.
-    89% of victims are males between the ages of 20 and 29; they are generally skiers, snowmobilers, or climbers.
-    Only a few seconds after an avalanche the snow quickly turns into ice, freezing hard as cement.
-    The United States ranks 5th in the world for avalanche danger.
-    The deadliest avalanche reported in American history was in February 1910, in Washington’s Cascade Mountains, the avalanche swept trains away and killed 100 people.

What to do in the case of an Avalanche?

It’s important to prepare properly when hiking, skiing and snowmobile in avalanche zones, you should always travel with a portable shovel and a backpack that it easy to get off.  While hiking or crossing a mountain, you should look for cracks within the snow’s surface; this is a sign of weak snow.  When crossing slopes, you should always cross one at a time. Another important device to have while traveling with a group are Avalanche Beacons, which are transceivers, which make it easier to find a victim.
    If you are ever in an avalanche, it’s important that you stay above the snow, on the surface of the snow, to make this easier move your hands and feet as if you were swimming. It’s also important that you let go of all poles and backpacks, in order to make yourself lighter and scream for help.  It’s important that you stay on the snow’s surface because immediately after the snow freezes as hard as cement, making it impossible to get out. If you find yourself stuck underneath the snow, make an air pocket , by punching out the snow around your face, remember to remain calm and yell for help.

Avalanche Scale:

Green in both American and European scales:
•    Snow pack is generally stable.
•    Only isolated areas of instability.
•    Back country travel is fairly safe.
•    Natural or human-triggered avalanches unlikely.
Yellow in both American and European scales:
•    Some areas of instability.
•    Natural avalanches unlikely; human-triggered avalanches possible.
•    Back country travel possible with caution.
Orange in American scale, Ochre in European scale:
•    Unstable areas probable.
•    Natural avalanches possible; human-triggered avalanches probable.
•    Back country travel possible with extreme caution.
Red in American scale, Orange in European scale:
•    Unstable areas highly likely on various slopes and aspects.
•    Natural and human-triggered avalanches highly likely.
•    Back country travelers should avoid steep slopes and wind-loaded slopes.
Black in American scale, Red in European scale:
•    Extremely unstable layers in snow pack.
•    Natural and human-triggered avalanches are certain.
•    Large destructive avalanches probable.
•    Back country travelers should avoid any steeply angled terrain or known avalanche areas.
"National snow and ice data center"

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What is a Mudslide?
A Mudslide or landslide is similar to an avalanche, however it is a fast moving flow of mud and other debris that quickly moves down a steep slope. The debris may include mud, water, boulders, rocks, trees and even cars.   These disasters are very unpredictable and dangerous

What causes Mudslides?

Gravity is the main cause of a mudslide, however there are many other factors that influence the disaster of a mudslide, which include; steepness of the slope, water saturation, erosion, construction, earthquakes, volcanic eruptions, and freezing and thawing.  Mudslides can also be generated by natural disasters, for example fires, volcanoes, earthquakes and storms.
    Mudslides occur when rain soaks into dry soil, the soil acts as a sponge and absorbs the water, when the soil has become to saturated it begins to break free and slide down the slope bringing along boulders, trees and rocks. Mudslides move quickly and destroy everything in its path.

Where are they most likely to occur?

 Mudslides are most likely to occur after a heavy rainfall or when snow melts at a rapid pace.  They affect terrain that has been affected by a forest fire, where vegetation as occurred or human modification as taken place. Generally dry soil with no plant life is affected.  They also occur at the bases of steep slopes or at the bottom of drainage channels.
    Mudslides are likely to occur in any area of the world, considering the factors that influence this disaster. Within the U.S, the states that are most commonly affected by mudslides are California, Oregon, Washington as well as Alaska and Hawaii.

Interesting Facts:

Mudslides are the cause of 25 to 50 deaths per year within the U.S and around 2 billion dollars in damage.
-    Mudslides can exceed the speed of 10 miles per hour.
-    Mudslides occur in all 50 states within the U.S.
-     The deadliest mudslide occurred in Vargas, Venezuela in 1999, killing 30,000 to 50,000 people.

What to do in case of a Mudslide?

It’s important to understand the proper safety precautions to take when a mudslide strikes. If you are inside, do not go outside, take cover indoors, and if you are outside relocate to the highest elevation.  Do not attempt to drive.


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