By avalanche we mean a mass of snow and/or ice which, suddenly breaking away from the top of a slope, starts to roll and slide down towards the valley, dragging along with it more of the snow lying on the slope and progressively increasing its speed, size, width of front, volume and its own quantity of mass.
An avalanche starts from a release caused by a change in the static balance of the snowpack.
Before going into the avalanche and snow-weather bulletins and how to read them, we first need to understand exactly what is meant by avalanche, avoiding an old and banal misunderstanding: that some avalanches are less dangerous than others.
From the Devoto Oli dictionary (2000-2001 edition)
Slavina (sluff): Mass of powdery snow that breaks away from high on a mountain and plunges down into the valley.
Valanga (avalanche): Mass of snow which, having broken away from high on a slope and rolling downwards, takes on ever greater dimensions, dragging along and burying whatever it meets on its way.
From the Dardano dictionary
Slavina: Mass of snow that slides down from a slope.
Valanga: Mass of snow that breaks away from a mountain slope and, plunging down into the valley, drags along with it whatever it meets, progressively increasing in volume.
From the Garzanti dictionary (1987)
Slavina: Slide of powdery snow that slips down a mountain slope, mostly during the spring.
Valanga: Mass of snow that plunges down into the valley growing progressively larger, often dragging rocks, stones and trees along with it.
From the Zingarelli dictionary (1996)
Slavina: Mass of snow that slides down a mountain slope.
Valanga: Mass of snow or ice that breaks away from the top of a mountain and plunges down into the valley sliding over the slopes, growing in volume as it falls.
Reading these very concise definitions you can already see how little is known about the avalanche phenomenon, and that apparently there is not much difference from the phenomenon of the sluff.
Definition of avalanche
What follows is our definition of avalanche, in our opinion the most complete and exhaustive one of the "AVALANCHE" phenomenon.
"By avalanche we mean a mass of snow and/or ice which, suddenly breaking away from the top of a slope, starts to roll and slide down towards the valley, dragging along with it more of the snow lying on the slope and progressively increasing its speed, size, width of front, volume and its own quantity of mass. An avalanche starts from a release caused by a change in the static balance of the snowpack. The best-known causes are: a skier or a group of hikers crossing the slope, a rock falling onto the slope, a sudden change in temperature, the action of the wind, an excessive build-up of snow on a very steep slope."
From this definition you can understand that an avalanche is dangerous for a number of reasons:
- the enormous speed it picks up as it comes down;
- its destructive force, due to the quantity of mass it drags along with it;
- the devastation caused by its size and volume, which sweeps up rocks, trees, skiers, houses, cars and whatever else lies on its path down to the valley;
- and finally the danger also comes from the transport of materials such as blocks of ice, rocks and debris that can cause injury.
The sluff seems to be a far less important phenomenon and, from a certain point of view, a less dangerous one. The use of the word “slavina” seems by now to have fallen out of use, in some dictionaries you cannot even find its definition, and for this reason we will not go into it any further on this site. No further distinctions between avalanche and sluff are needed, since we take it for certain that a fall of snow from high on a slope, whatever name it takes, can be potentially dangerous.
Definitions for interpreting the European Avalanche Danger Scale
SMALL AVALANCHES: stops on a steep slope (steeper than 30°). Can bury, injure or kill a person;
MEDIUM AVALANCHES: on a steep slope (more than 30°) reaches the bottom of the slope. Can bury and destroy a car, damage a lorry, destroy a small house or bend or break a few trees;
LARGE AVALANCHES: runs over gently sloping ground (well under 30°) for a distance of more than 50 m and can reach the valley floor. Can bury and destroy a railway wagon, a large vehicle, several buildings or part of a wood.
As we will see in the article on reading the avalanche and snow-weather bulletins, small avalanches are possible even at the first danger level. This means that the risk is always there and that even in the most remote of cases an avalanche, however small, can bury, injure or kill a person.
Frequently asked questions
What is the difference between an avalanche (valanga) and a sluff (slavina)?
For the dictionaries the slavina is a mass of powdery snow that slides down a slope, while the valanga grows in volume, dragging along whatever it meets. For people who go to the mountains the distinction matters little: any fall of snow from a slope is potentially dangerous.
What causes an avalanche to release?
The release comes from a change in the static balance of the snowpack. The best-known causes are skiers or hikers crossing the slope, a falling rock, a sudden change in temperature, the action of the wind and an excessive build-up of snow on very steep slopes.