Every year, avalanches around the world total over a million, distributed along the various snow covered mountain tops and high peaks. While most avalanches happen when nobody is around, or they are small snow falls, occasionally when the conditions are right and the trigger is human, there can be destructive results to both life and property. In order to prevent avalanches from happening, there are several things done, one being informed of possible avalanche conditions and being knowledgeable of what terrain to avoid, another is direct steps done to block avalanches or make them unlikely to start, or the finally the direct approach, when avalanches are triggered on purpose.
General awareness of the conditions of a mountain and the possibility of an avalanche occurring are important facts to recognize before venturing out onto a mountain. Conditions for avalanches can be differing layers of snow build up, where one layer slides on another. In the case of the top layer sliding, there is less damage. If the bottom layer starts sliding against the surface of the mountain because of the weight of the top layer, then the damage and danger will be high. Checking the conditions of the snow pack can be done by cutting a small sectioning in the snow of a lesser slope, and seeing how the layers differ. In some cases, there may be a layer of ice that causes the sliding, or melting below the surface. By determining the severity of conditions, an avalanche can be avoided by simply not venturing across an at risk area.
Apart from layers of snow pack, outside conditions of abrupt warming or cooling can cause a risk of avalanche, as well as building formations of snow at the top of peaks that if dislodged, could provide enough force for a chain reaction. Lumps or piles of snow on flat layers below can also be potential triggers. Areas most at risk are those that are steeper and wide stretches without trees. Unintentional triggers can be caused from disrupting the surface or upsetting a trigger.
Avalanche prevention on high at risk areas that are frequented often by people can be done with snow fences or tree planting at lower elevations. This method of blocking disrupts the long and unbroken stretches of layers that lead to the domino effect that creates large snow falls down the mountain. Fences and barriers in sections will stop the momentum of some slides by keeping a surge at bay. While the entire mountain side may end up experiencing an avalanche, the snow at the topmost part will be prevented from traveling past a certain part, thus diminishing the effects of the avalanche.
Finally, the direct prevention approach is to trigger them safely while no one is around. This method of avalanche prevention is usually taken by ski slopes that use explosives shot by gun or dropped by helicopter onto the top part of a snow pack. While still dangerous, these triggered avalanches will have people out of the way and can fall the length of a mountain without worry. This alternative is far-preferred to simply letting an unsuspecting skier from triggering a possibly deadly avalanche.