We allowed the added snow to sinter for approximately 30 to 60 min before completely isolating the block and performing a PST. For the first set of experiments we used a cardboard frame the dimensions of a standard Propagation Saw Test (PST) and added 5, 10, 15, or 20 cm of disaggregated snow on top of PST columns on 11 sampling days.
We developed a field method to rapidly increase the load on existing weak layers, and conducted two different sets of experiments. This study quantifies both: 1) the effect of increasing load on the interaction of the slab and weak layer over short time scales, and 2) the longer term stabilizing changes following loading. This suggests that loading favorably changes snow cover properties for avalanche release over short time scales (e.g., minutes and hours), and that changes over longer time scales (days or longer) help to stabilize the snowpack. In the absence of further loading avalanche activity decreases over time. Most dry slab avalanches occur during or immediately following loading by snowfall or wind deposition.
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