How to Perform a Shovel Shear Test
The shovel shear test is a quick test to identify weak layers in the snow pack when you are skiing in avalanche terrain. When used with other snow tests, this test will help keep you safe. It only takes a few minutes and shows you where dangerous, weak layesr lurk in the snow.
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Instructions
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The Shovel Shear Test
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1
Isolate a column of snow with your shovel and saw. It needs to measure 12 inches by 12 inches and be at least as deep as your shovel blade, which is usually about 18 inches. Make the edges smooth and straight. You can use a snow saw to help with this.
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2
Insert the shovel blade at the back, or uphill side, of the snow column.
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3
Apply gentle force with both hands on the shovel blade in the downhill direction.
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4
Watch the column. As pressure is applied, the column will smoothly shear, or slide, along any weak layers. These signify unstable, or unsafe, snow. If there are no weak layers, the column may break. This means the snow is more stable or safe.
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5
Mark where the weak layer shears off the column. Repeat steps 1 through 4 several times. Several shovel shear tests are required to get an accurate picture of weak layer locations.
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6
Interpret your results. If the column fails in the very early stages, the shear is described as "very easy." If it fails with minimal shovel pressure, it is "easy." If the column fails with moderate pressure, it is "moderate." And if the column does not fail or fails after forceful prying, it is "hard." "Very easy" and "easy" shears are associated with weak, unsafe, unstable snow. "Moderate" and "hard" shears are associated with more stable, safer snow.
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7
Perform other snow tests--compression, rutschblock and extended column--to give you more information on snow stability. They will help you to make safer decisions. No snow test is perfect.
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Tips & Warnings
The shovel shear test only helps to identify weak layers. Don't disturb the snow that you are testing, because it could lead to inaccurate results. The more you practice this test, the better you will become at interpreting the results. Perform this test on an area similar to where you want to ski. The best way to get educated about avalanche safety is to take an course.
Shovel shear results are often hard to interpret, so do other tests as well. The test results are affected by the quality of the snow column. Straighter, smoother sides make for more reliable results. You can only test a small area with the shovel sheer, so do multiple tests.
