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Vulnerability: Caught in an avalanche – then what are the odds?

Submitted by jbjamies on Thu, 06/14/2012 - 9:20pm

Publication Type:

Conference Paper


International Snow Science Workshop, Volume 1, Anchorage, Alaska, p.1-8 (2012)


avalanche, balloon packs, buildings, probability of death, recreation, risk, roads, vulnerability, worksite


Vulnerability is an essential component in qualitative and quantitative avalanche risk analyses. It is the probable consequences given that the element-at-risk is hit by or caught in an avalanche. Since consequences vary with avalanche characteristics, there is a level of vulnerability associated with each type or size of avalanche. The avalanche size classification based on destructive potential is well suited to classifying vulnerability into different levels. We review vulnerability for vehicles on roads, buildings as well as backcountry recreationists and workers. Quantitative vulnerability typically requires some data, although expert estimation can be used with or without data. Quantitative vulnerability has the advantage that it can be used in comparisons with other risks to determine if a risk is acceptable. For backcountry recreation, data from non-fatal injuries are limited, so most calculations of vulnerability for people use only the expected probability of death. Using Canadian accident data, we estimate the vulnerability (probability of death) to roughly 0.004 to 0.007 for a Size D2 avalanche (destructive scale) and ten times higher for a Size D3 avalanche. We show how balloon packs can change the vulnerability of recreationists, and include an example of how vulnerability can be used in an avalanche risk assessment for a worksite.


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