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Understanding risk, hazard, danger, vulnerability and exposure

05.12.2025

Avalanche commissions operate within the civil protection framework, managing risk, defined by its components hazard, exposure and vulnerability, as opposed to avalanche danger, which describes the natural avalanche conditions themselves.

01

Civil protection and avalanche commissions

The civil protection system is the coordinated set of structures and skills that work to prevent, manage and overcome emergency situations that threaten the safety of people, property and the environment. It acts through risk forecasting, prevention and mitigation, protection, management and overcoming of emergencies, involving public institutions, law enforcement, volunteers and citizens.

Within this system, avalanche commissions play a key role in mountain areas prone to avalanche risk. They are made up of technicians and experts, but also of local people who have a deep knowledge of the terrain as well as the prevailing local (weather) conditions and, therefore, experience in dealing with the specific problems. The commissions assess the risk at the local level and provide support to decision-makers regarding the measures to be taken, such as road closures or evacuations. The avalanche commissions therefore deal with the management of avalanche risk in order to prevent damage and potential casualties, reducing the exposure and vulnerability of the population.

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The concept of risk

Risk can be defined as the probability that an adverse event, such as an avalanche, will occur causing a negative impact – or damage – on items exposed to a hazard. More formally, risk is the combination of three essential components: Risk = Hazard x Vulnerability x Exposure

To better visualize these interconnections, we can imagine a diagram of the components of risk:

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The components of risk in the avalanche context

In the man-made Alpine context, where the territory is affected by human presence through settlements, infrastructure, and economic activities, it is essential to draw a clear distinction between risk and hazard (as risk’s component) on the one hand and danger on the other.

Hazard

A hazard is something with the potential to cause harm; it exists regardless of whether harm occurs. With respect to avalanches, this might, for example, be a steep mountain slope. Danger is the condition where harm is imminent. It’s more immediate than a hazard. Avalanche danger, in this respect, is the realization of the avalanche hazard, e.g., if the steep mountain slope is loaded with a critical amount of snow and an avalanche event is possible.

The following map shows avalanche paths and the extent of potential avalanche events. It does not depict imminent dangers but rather avalanche hazards. The colours represent different avalanche sizes with varying probabilities. The map also illustrates the exposure of roads and buildings that may be affected by smaller or larger avalanches. Consequently, infrastructure that is only impacted by larger (and therefore rarer) avalanches is less exposed than infrastructure that may also be affected by smaller (and thus more frequent) avalanches.

Schnals (South Tyrol) – Gefahrenzonenplan © Geo Browser Provinz Bozen | snow institute

Vulnerability

Vulnerability is the risk component that expresses the propensity to suffer damage. In the avalanche commissions’ context, it is related to the fragility of buildings, infrastructures, ski lifts, vehicles, skiers, pedestrians, etc., located in the path of the moving snow mass. It is crucial to consider their level of (structural) strength or resilience to the avalanche event. For example, buildings located in avalanche-prone areas are significantly vulnerable, particularly in exposed walls, openings, and roofs; a snow plough might be less vulnerable than a passenger car; a pedestrian walking on the slope-facing side might be more vulnerable (with respect to a small glide snow avalanche) than a pedestrian walking on the slope-opposite side.

This building was heavily damaged by an avalanche. Looking at the definitions of the risk components we can report that it was at (high) avalanche risk, because

There was an avalanche hazard; otherwise there would not have been an avalanche.
The building was exposed to the hazard; otherwise it would not have been affected.
The building was vulnerable; otherwise, it would not have been (so severely) damaged.

Rifugio Pian dei Fiacconi (TN) – December 2020 © Archivio PAT | snow institute

Exposure

Exposure encompasses people and infrastructures, that are located in areas potentially affected by avalanches. The exposure is closely linked to the probability of a damaging event. For a road that leads through steep, grassy slopes it is more probable to be affected, e.g., by glide snow avalanches than for a road that runs through a dense forest. Consequently, the latter is less exposed to avalanches. Exposure is also about time: The longer an object or a person is exposed to an avalanche hazard, the more probable it is to be affected by one. Therefore, exposure (and also risk) can also be decreased by shortening the length of stay.

This road is obviously crossing an avalanche path. On this spring day, a wet snow avalanche blocked it. Looking at the definitions of the risk components we can report that the road was at (high) avalanche risk, because

there was an avalanche hazard; otherwise, there would not have been an avalanche and, moreover, there would not be a well-known avalanche path.
the road was exposed to the hazard; otherwise, it would not have been affected.
the road was vulnerable; otherwise, it would not have been blocked. If there would have been any kind of permanent measures, e.g., an avalanche gallery or a tunnel, the road would not have been vulnerable.

Assuming the cars were parking and not driving while the avalanche hit the road, we can conclude: They were not at risk, because they were not exposed. They were parking on a safe place with no avalanche hazard. However, in principal, they would have been vulnerable, since if this avalanche would have hit them they would have been severely damaged.

Monclassico (TN) – loc. Montes 15 aprile 2013 © Archivio PAT | snow institute

Risk occurs when someone or something, that is vulnerable, is exposed to a hazard.

Why is the term risk and its components of such great importance in the context of avalanche commissions? Because avalanche commissions are risk managers who aim for reducing or eliminating as many of the risk components as possible.

Coverphoto: : Val Salei (Trentino) @ A. Gasperi | snow institute