%0 Conference Paper
%B International Snow Science Workshop
%D 2012
%T How do you stress the snowpack?
%A Thumlert, S
%A Jamieson, B
%A Exner, T
%C Anchorage, Alaska
%K snowpack stratigraphy, stress, snowmobiler, skier, avalanche release
%P 506-512
%V 1
%X In the majority of fatal avalanches, skiers and snowmobilers apply load to the snowpack which triggers the initial failure in a weak layer. Understanding how the stress from a dynamic surface load transmits through the snowpack can help people avoid situations where they can trigger slab avalanches. Capacitive sensors were used to measure this stress within the mountain snowpack. The  three main variables affecting stress transmission through the snowpack investigated in this paper are the type of loading, depth and properties of the snowpack. A decrease in stress was observed with increasing depth. At specific depths, snowmobiles added more stress than skiers did, thus increasing the probability  of initiating a fracture in a weak layer and releasing a slab avalanche. The increased penetration depth of snowmobiles into the snowpack compared to skiers is the primary reason for this increase in stress. Falling skiers added about 3 times more stress than typical skiing. Skiers added about 1.5 times more  stress than snowboarders. A decrease in stress was observed with increasing depth. Supportive surface layers created a “bridging effect” that spread stress out laterally and decreased the depth to which it penetrated.
%8 16/09/2012