A Rutschblock test (pronounced ROOTCH BLOCK) is a snowpack compression test used by winter adventurers, backcountry guides, and avalanche forecasters to test for avalanche danger. It is designed to simulate the shock that a skier, snowboader, or snowshoer/climber, exerts on the snowpack when they cross it, and helps predict whether the a slope is more or less likely to avalanche.
Snowpack Column Testing
Avalanche forecasters and snow rangers use several different forms of column tests to determine the thickness and strength of layers in the snowpack and how likely they are collapse and sheer apart, causing an avalanche.
These tests all involve digging a snow pit into the snowpack and cutting out a self standing column of snow, like the one shown above, using a snow saw. Different levels of force are then applied to the top of the column to see how much weight is required to make it collapse.
The problem with digging these narrow 30 x 30 cm square columns is that you can get different results from adjacent columns in the same snowpit, and you need to dig of lot more of them to identify a reliable trend. Alternatively, you can isolate a much larger column of snow called a Rutschblock that is 200 cm wide (2 meters), 150 cm deep (1.5 meters), and up to 120 cm tall, cut out of the snowpack on a slope that has a 30 degree slope or greater.
I had the opportunity to learn how to do this test in famous Tuckerman Ravine. Tuckerman is a very deep ravine, located at the base of Mt Washington in New Hampshire’s White Mountains, that has a lot of avalanche activity and is the location of a major avalanche forecasting center. The ravine is easterly facing, on the lee side of Mt Washington, making it very susceptible to snow loading and wind slab formation from the high speed winds that continuously sweep the area, year round.
EMS Instructor Dave Lottmann explains the Rutschblock Test
After digging the large Rutschblock, an avalanche forecaster puts on a pair of skis and jumps on top of the snow column using a choreographed set of movements design to simulate different loads and pressure shapes. The results are coded using well defined system of acronyms and then recorded in waterproof snow pack observation booklets for forecasting and interpretation by avalanche rangers.
A Borderline Rutschblock Test Failure
In order to set up a Rutchblock test, you need a clinometer to measure the angle of the slope you want to test, a shovel to dig out the snow pit around the block, an avalanche probe to measure the blocks dimensions and height, and a long wire Rustchblock saw that is used to cut through the back of the block, so that it’s isolated from the rest of the uphill slope.
Learning how to do a avalanche forecasting test like this and interpret it requires a few days of instruction and a lot of practice, but it’s a very valuable test to be able to perform to protect yourself and your friends from getting caught in an avalanche in the backcountry.
For more information about avalanche forecasting tools, education materials, accident reports and conditions near you, visit http://avalanche.org/.
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