SNOWPACK TESTS Tests for Propagation Propensity PROPAGATION SAW TEST

30cm wide x 100cm upslope (or upslope length = to weak layer depth if >100cm deep) Isolate block below weak layer of concern.

Description

Propagation to end

Slab Fracture

Self-arrest

Data Code

The fracture propagates in the weak layer in front of the saw uninterrupted to the end of the column. END

The fracture propagates in the weak layer in front of the saw and stops where it meets a fracture through the overlaying slab

The fracture propagates in front of the saw but self-arrests somewhere along the weak layer before reaching the end of the column

Recording PST: ‘PST’ x/y (Arr, SF, or End) down z on yymmdd’

DT1 to DT10

Hand Shear Tests

These tests can be used to quickly gain information about the snow structure. They should not be used to replace stability tests but can be used to estimate the spatial extent of relatively shallow weak layers.

Procedure a) With your hand or a ski pole make a hole in the snow deeper than the layer you with to test b) Carve out an isolated column of snow c) Tap on the surface of pull on the column of snow in the down slope direction d) Record your results with the name of the test, weak layer, depth and rate the result as Easy, Moderate or Hard. (example: Hand Easy or Hand-E) Also include pertinent terrain parameters such as slope angle, aspect and elevation. e) Use other methods to investigate the weak layer or surface as needed.