Technical information, news, research, and opinion on avalanches, snow safety, and winter backcountry travel.

Wednesday, March 24, 2010

Exposure Is Personal

We reached the dizzy heights of that dreamed of world—Pink Floyd

NOTE: I updated this post on March 28th, 2010. I don't include the role of avalanche size in the discussion on danger because it is possible to be killed by a very small avalanche.

Often times you hear people discuss "mitigating risk", or "mitigating hazard", and so forth. From these discussions, it's clear that many people can't distinguish between hazard, danger, and risk. ( Which is perfectly understandable since these words are fuzzy and woefully imprecise. )

There is a difference between exposure, danger and risk, and in addition to the differences, it's also very important to understand how these variables interact. Risk is classically defined as chance, consequences, and exposure, but in this post I'm going to explicitly re-fashion the key elements of risk to revolve around your personal risk acceptance level, since the real source of most risk is from within.


You are always exposed to avalanches during travel through avalanche terrain—that's why it's called avalanche terrain. Usually during times of high avalanche danger, you can reduce exposure by choosing gentle terrain, or by using very careful route-finding / travel technique when traveling through exposed terrain.


The actual avalanche danger may be very low or very high. The danger level reflects the likelihood of avalanche formation, as outlined in the public avalanche bulletin, or as judged by your own observations in the backcountry. You cannot modify the current avalanche danger, but through informed terrain choices, you may be able to choose slopes where avalanche danger is lower.


Your personal risk acceptance level determines your tolerance for exposure and danger, which in turn determines the chance of avalanche involvement and the consequences thereof. This is why avalanche professionals often say most avalanche accidents are the result of choice, not chance. Again, the most important source of risk comes from within.

Scales For Exposure, Danger, And Risk

Figure 1.1. Avalanche danger scale from LOW to EXTREME. This graph shows the likelihood of avalanche formation, and this information is available in the public avalanche bulletin, or formed by your own observations in the field.

Figure 1.2. Terrain Exposure Scale. This graph shows the amount of exposure for a given route or geographic area. One problem is that there are few terrain ratings available for Washington State. ( I've assembled ratings for some popular areas, but the list is still very incomplete. )

Figure 1.3. Risk Acceptance Scale. This graph shows the amount of risk you are willing to tolerate. Baseline risk tolerance varies greatly by individual, and specific individuals have different risk tolerances at different times as well. You may generally accept higher risk, but even this will vary.

Your Personal Exposure Score

Calculate your personal exposure by using the following formula.

risk tolerance + avalanche danger + avalanche exposure = personal exposure score
  • Avalanche Danger Score: Current danger level, 1-5, multipled by 2.
    • Considerable = 6.
  • Terrain Exposure Score: A number from 0 to 10.
    • 0 = no exposure.
  • Personal Risk Score: A number from 0 to 10.
    • 0 = low risk tolerance.
One of the most important, and least discussed elements of avalanche safety, is the complicated relationship between exposure, danger, and risk, and the process of managing awareness and uncertainty. Reducing exposure commonly makes people feel less uncertain, even though a reduction in exposure may not have the desired effect when you actually want more risk.

Always evaluate the moments when you seek to preserve risk. Often these are moments when we look for something fun, exciting, or notable.

Further Reading

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