RUTSCHBLOCK PRECISION, TECHNIQUE VARIATIONS AND LIMITATIONS

The Swiss rutschblock test provides practical information about the st ability of snow slabs. However, its use by avalanche workers and ski g uides is limited by the time required to perform the test and recommen ded minimum slope inclination (30-degrees). The present study shows ho w time requirements can be reduced by cutting rutschblocks with cords or specialized saws - faster techniques that do not appear to affect t he results. Comparing the rutschblock results with a stability index d eveloped in Switzerland shows that the recommended minimum slope incli nation can be reduced to 20-degrees, provided a second person is prese nt to observe the small block displacements associated with slope incl inations below 30-degrees. Sets of rutschblocks on slopes that vary in inclination by 8-degrees or more are used to determine the effect of slope inclination on rutschblock scores. Also, the frequency distribut ions of six large sets of repeated tests are used to estimate the prec ision of one or two tests on a uniform slope.