The most famous myths about Snow and Avalanches
Number 2 : "It's flat, or at least not very steep"
It's a very deceptive myth, especially because a terrain can be perceived as steep or not depending on each person's technical abilities, during the ascent but especially during the descent.
But why is this concept wrong?
It's true that most avalanches that can affect people moving on snow start on slopes between 30 and 45 degrees of inclination; but we're talking about the slope at the point of departure, and once the avalanche starts moving, whether triggered or not, it can continue to slide down even on less steep terrain
For example, if we're traveling on a snow-covered road, which is certainly not very steep, but above us we have steep slopes, an avalanche could still hit us even on that flat road.
In good weather, it's easier to see what's above our heads: other people, animals, steep slopes, cornices, and any other potential avalanche trigger. In bad weather, instead, this very important observation is more difficult if not impossible.
This is where map-reading, snow and weather knowledge, and our own behavior, such as maintaining safety distances, can help us reduce risks.
Another classic example, where the low slope can be misleading, is the remote triggering.
If wind slabs have formed, a very likely occurrence with light snow, they will be composed of snow with cohesion, weak or strong as it may be; that is, the snow crystals will be more or less cohesive together.
Our passage over the slab, even on flat terrain, can transmit energy to the snow cover, energy that, with the vibrations we caused, can be transmitted from crystal to crystal even uphill and reach the weak point of the slab and trigger it even tens of meters above us.
Let's also remember that wet snow avalanches, a rarer case but still possible under high temperatures, continue their run even on slopes below 20 degrees.
But what are the systems for easily and correctly understanding the inclination of a slope?
In addition to reading the map, and measuring the distance between the contour lines, on the ground we can use a clinometer or the Ski Poles Test (two identical ski poles are required). Let’s see how it works:
Place one ski pole vertically on the snow.
Slide the second ski pole horizontally along the vertical one until it touches the snow on the uphill side.
If the horizontal ski pole touches the snow on one side and the top of the vertical ski pole’s knob on the other, the slope will be about 45 degrees.
If the horizontal ski pole touches the snow when it's halfway up the vertical one, the angle will be 27 degrees.
It's certainly an empirical and not very precise method, but useful in the field and very quick.
One last empirical but very simple and useful note: when an intermediate to advanced ski mountaineer, ascending a slope, can no longer make turns proceeding normally but has to stop to make a turn in place, we can consider that they have reached a slope inclination of 25/30 degrees.
And finally, remember that inclination and slope are not the same thing; inclination is measured in degrees, while slope is measured in percentage (for example, roads are generally measured in slope, while our slopes are measured in inclination).
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Ernesto Bassetti
Ernesto is one of the leading snow and avalanche experts in Italy and beyond.
By passion and by profession, he has been involved in mountain safety for over 40 years, with particular attention to the avalanche issue.
He is co-founder, and until 2020 Vice President, of MND Group; important international player in the field of mountain infrastructure and world leader in controlled avalanche release systems.
He is a ski instructor, National Ski Mountaineering Instructor, former director of the Mario Righini Ski Mountaineering School.
He was promoter, co-founder and soul of the "Servizio Valanghe Italiano" (Italian Avalanche Service), of which he held the Presidency for 18 years.
