From avalanche danger to avalanche risk … and why it depends on the terrain.

26.06.2023

In alpine winter sports, too, “danger” is often and regularly confused with “risk” and these two terms are often used indistinctly. This also applies to “avalanche danger” and thus the “avalanche risk” that freeriders take. However, clarity in these terms is not only important for the young skiers themselves in order to understand the avalanche forecast and the possible consequences of their actions, but also for communication to the outside world. After all, a high danger does not necessarily mean a high risk.

This article is about:

01

What is the avalanche danger?

This question is discussed in more detail in the article “What is the avalanche danger level”. Nevertheless, we will provide a brief summary below because this question is crucial for two reasons:

  • It helps us to better understand the definition of the danger levels and the warnings issued by the avalanche warning service experts.
  • It shows the options we can take to avoid exposing ourselves to (unintentionally high) risk.

At the top of the avalanche danger information pyramid is the danger level, which is assessed separately for each relevant avalanche problem. The avalanche forecast from the avalanche warning services then communicates the highest danger level of all the problems listed. The forecasters are not completely free in their assessment, but are bound by the so-called EAWS matrix (European Avalanche Warning Services). Depending on the stability of the snowpack, the number of danger spots and the size of the avalanche, a danger level is assigned.

Since the winter of 2022/23, these three parameters (snowpack stability, number of danger spots and avalanche size) have been explicitly stated (per avalanche problem) in the Euregio avalanche.report of Tyrol-South Tyrol-Trentino, for example. This means that the user knows how to assess the current snow (cover) situation. For example, a “very poor” snowpack stability with “many” danger spots and “large” avalanches to be expected results unsurprisingly in avalanche danger level 4 (high avalanche danger).

EAWS Matrix © snow institute

However, the avalanche danger depends not only on the danger level, but also on the terrain! This is plausible and understandable as there can never be an avalanche risk on the flat meadow on the valley floor, outside of any catchment areas, regardless of the snowpack structure – which results in the above-mentioned parameters.

Although there are already automatically generated maps for some areas in the Alps (e.g. WhiteRisk, Skitourenguru, etc.) that link the terrain and the avalanche danger, the danger level by definition takes no account of the terrain: the avalanche danger level is the same everywhere from a regional perspective!

The risk only comes into play with the terrain or the stay in potential avalanche terrain – which, as is known, must be steeper than 30 degrees or lie in the run-out and deposition area of avalanches.

EXCURSE: ATES

The Avalanche Terrain Exposure Scale (ATES) from Parks Canada classifies the terrain – and not the snowpack structure – in terms of potential avalanche danger. Corresponding terrain maps are common in North America and are also slowly becoming more widespread in the Alpine region. They are ideal for classifying the avalanche risk in open terrain into the following three categories at a glance:

  • Class1 “simple/simple”
  • Class 2 “challenging/demanding”
  • Class 3 “complex/complex”

Relevant parameters such as slope inclination/shape, forest cover, terrain traps, avalanche probability/year, characteristics of the break-off/deposition zone and avalanche path, route alternatives, exposure time and glaciation are defined in a detailed technical table, but also in a simple version for the general public. More details can be found here.

A simplified ATES overview in the gallery

02

What is the avalanche risk?

A risk arises when a person – or property – is exposed to danger. Specifically, if, for example, a person can be caught in an avalanche while freeriding. The prerequisite for this is that this person exposes themselves in avalanche terrain when there is a risk of avalanche.

The level of risk is defined by the probability of occurrence and the extent of damage:

  • The higher the probability of an avalanche occurring – e.g. very poor snowpack stability, many danger spots/trigger points and extremely steep slopes – the higher the risk, provided that damage (e.g. burial of a person or destruction of a building) is also possible.
  • The risk also increases with a higher extent of damage – e.g. burial of a group instead of a single person.
03

What role does the terrain play?

As can be easily deduced from the definition of risk, the risk can therefore be controlled or reduced either by the probability of occurrence or the extent of damage.

However, as a winter sports enthusiast, I cannot change or influence the stability of the snowpack, the number of danger spots or the size of the avalanche on the individual slope to be skied, so I can only choose the terrain to reduce my risk.

The most important message in this context is:

"If the snow is the problem, the terrain is the solution!"

Risk reduction is therefore only possible if I am willing and able to move around in the terrain when there is a high avalanche risk in such a way that the triggering of an avalanche or an injury and burial can be prevented.

Essentially, this means: waiving or excluding

  • Terrain with a slope of over 30 degrees
  • large slopes
  • Terrain traps and catchment areas
04

What are standard measures in the field?

Risk reduction is therefore possible even in the event of a high avalanche risk, provided I make a strict effort to reduce the probability of occurrence and the extent of damage. The so-called standard measures, which aim in particular to reduce the risk via the extent of damage, are helpful for this.

For example: You are on a steep slope with a group of three and you decide to ski individually. This primarily reduces the extent of damage, as only one person is injured or killed in an avalanche and not three.

With adequate emergency equipment, I can’t change the probability of an avalanche occurring, but I can increase my chances of survival through faster rescue times – if my tour partners are appropriately trained.

The following standard measures regarding behavior in the field have proven their worth and can also be described – to get rid of the official German “standard measures” – simply as what they are: good style!

05

Conclusion

The avalanche danger alone says nothing about the individually chosen or unconsciously assumed risk of freeriders. A risk only arises through their exposure in the danger zone. However, those who are able to reduce the probability of occurrence and/or the extent of damage through various measures can be “safe” even when the danger is high.

The demand for penalties for freeriders and ski tourers who are out in the terrain when there is a high risk of avalanches is pointless, as a high danger does not necessarily mean a high risk.

Finally, it should be noted that it is of course possible to take a high risk even when the avalanche danger is low, for example by making ascents and descents in the terrain explicitly mentioned in the avalanche forecast (or the avalanche problem) or by exposing yourself to complex terrain.

The last images show skiers who have low or high exposure in the terrain and, in combination with a low or high avalanche risk, choose their personal risk to varying degrees.

© snow institute
© snow institute
Cover picture: © snow institute | argonaut.pro