An avalanche is a mass of snow that slides rapidly down an inclined slope, such as a mountainside or the roof of a building. Avalanches are triggered by either natural forces (e.g. precipitation, wind drifting snow, rapid temperature changes) or human activity. In mountainous terrain, they are among the most serious hazards to human life and property. Avalanches are sometimes called snowslides.
WHAT CAUSES AN AVALANCHE?
An avalanche occurs when stress from the pull of gravity and/or applied load (such as a skier) exceeds the strength of the snow cover. Strength is derived from bonds between snow grains. A slab (a cohesive layer within the snowpack) avalanche can occur when the following three conditions are present: – A snow-covered slope – A slab of snow resting on top of a weak layer of snow – A triggering mechanism
WHERE DO AVALANCHES OCCUR?
Most avalanches occur in the backcountry, outside the boundaries of developed ski areas. About 90% of all avalanches begin on slopes of 30-45 degrees, and about 98% occur on slopes of 25-50 degrees. Avalanches strike most often on slopes above timberline that face away from prevailing winds (leeward slopes tend to collect snow blowing from the windward sides of ridges). However, it is possible for avalanches to run on small slopes well below timberline, such as in gullies, road cuts, and small openings in the trees. Very dense trees can help anchor the snow to steep slopes and prevent avalanches from starting; however, avalanches can release and travel through a moderately dense forest.
ARE THERE AVALANCHES IN THE BOLIVIAN ANDES?
Yes there are, that’s why you should be very careful about scheduling your ascent, in Bolivia there only two seasons, a RAINY season (December – March) and a DRY season (May – October).
What is really curious here is that the Dry season is the Bolivian winter (the weather is more stable and there’s no snow or rain) in the other hand there is the Rain Season that is the Bolivian summer, it’s not recommendable to schedule your trip to Bolivia on this season (if you want to climb), on this season there an avalanche danger.
As a responsible company we don’t organize any ascent to any mountain on rainy season due this reason.
We’d love to answer any question you may have regarding this and many other subjects related with the mountains.