Avalanches are natural phenomena that occur when a considerable mass of snow falls off and slides down the slopes of hills and steep terrain. The word, as such, comes from the French avalanche.
The avalanches occur as a result of the accumulation of snow in mountainous areas where the slopes of the mountains and the concurrence of a series of physical and meteorological factors give rise to movements of large amounts of snow.
The avalanches can be superficial if only the outermost part of the snow cover is mobilized, or in the background, when not only the snow layer is mobilized, but even this, in its movement, erodes the hillside substrate and it takes with it part of the vegetation cover of the slope.
Avalanches can be formed by any of the following causes:
- Due to lack of homogeneity between the snow layers.
- Due to excess weight, when the amount of snow is greater than a surface can withstand.
- By rain, when a recent layer penetrates, and it slips due to the weight of water.
- Due to changes in ambient temperature that may affect snow cohesion.
- Due to the soil conditions, especially when they are this, it is suitable for the sliding of materials along their surface (clay, smooth, wet or icy terrain).
Depending on their magnitude, avalanches can be classified on a scale ranging from weak to very strong, the latter being highly dangerous.
Depending on the victims and damages that an avalanche can cause, it can also be considered a natural disaster.
Avalanche can also designate, in a general way, any considerable mass of a material that emerges and precipitates from a slope. For example: “The detachment of the tree produced an avalanche of land.”
The word avalanche can also be used figuratively in reference to a large amount of something. For example: avalanche of kisses, avalanche of praise, human avalanche, etc.
Avalanche of loose snow
It is the type of avalanche that occurs after heavy snowfall. Fresh snow, accumulating more than 25 cm thick, is conducive to slipping, especially when it falls on a mass of smooth snow. This type of avalanche usually carries more and more snow on its route.
The plate avalanche occurs when a compact snow surface falls off and slides down the slope. It looks like a block of snow cut from its surroundings. It is a fairly frequent type of avalanche and carries great risks.
Avalanche of wet snow
The avalanche of wet snow is typical of the season when temperatures begin to rise, towards the end of winter and the beginning of spring. They are usually slower and lower in suspension.