Comparative Avalanche Hazard Scales

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Note that these stability tests cannot be used to affirm a slope is safe to venture onto. The results from the test must be weighed with all the other factors gathered about local avalanche conditions (human factors, weather,terrain and snowpack) when deciding to venture onto avalanche terrain. The term "stable" as used below does not indicate that the terrain is safe from avalanche hazard. The terms "moderate instability" or "unstable " do indicate that similar slopes should be avoided. If you are interested in the when, where and what of these tests I'd strongly encourage you to take a basic avalanche (level 1) course.
Snow Stability Tests

 

Stuff Block Test

Shovel Shear Test

Rutschblock Test

Drop distance

Shears fails

Shear fails

0 cm

Unstable

During excavation

Unstable

1

During excavation

10 cm

Unstable

Inserting shovel behind

Unstable

2

Approaching or stepping onto block

20 cm

Unstable

Easy shear

Unstable

3

Down weighted

30 cm

Moderate instability

Easy shear

Unstable

4

One jump in place

40 cm

Moderate instability

Medium shear

Moderate instability

5

Two jumps in place

50 cm +

Stable

Hard shear

Stable

6

4-5 jumps in center of block

Stable

No shear

Stable

7

Doesn’t fail

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Avalanche Forecasters Hazard Scale

LOW
(green)

Natural avalanches very unlikely. Human triggered avalanches unlikely. Generally stable snow; isolated areas of instability exist. Travel is generally safe. Normal caution advised.

MODERATE
(yellow)

Natural avalanches unlikely. Human triggered avalanches possible. Unstable slabs possible on terrain above 25 degrees. Use caution in steeper terrain on certain aspects.

CONSIDERABLE
(orange)

Natural avalanches possible. Human triggered avalanches probable. Unstable slabs probable on steep terrain. Be more cautious in terrain above 25 degrees. Be aware of potentially dangerous areas of unstable snow.

HIGH
(red)

Natural and human triggered avalanches likely. Unstable slabs likely on a variety of aspects and slope angles. Travel in avalanche terrain not recommended. Safest to travel on windward ridges or lower angle slopes without steeper terrain above.

EXTREME
(black)

Widespread natural and/or human triggered avalanches certain. Extremely unstable slabs on most aspects and slope angles. Large destructive avalanches possible. Travel in avalanche terrain should be avoided and travel confined to low angle terrain well away from avalanche path runouts.


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