Fig. 1: Slab avalanche and setup of the experiements.
From: Signatures of the sub-Rayleigh to supershear fracture transition in snow avalanche experiments
a Accidentally triggered snow slab avalanche in Alaska, 2014. Photo: Oli Gagnon. b Image of the experimental avalanches consisting of snow fracture tests performed in Davos, Switzerland. c Schematic representation of (b). The experimental design involves isolating a column with length L ≈ 10 m and width b = 0.3 m. The column height is given by the overall snow height, which is the sum of the thicknesses of substratum, weak layer (orange) and the thickness D of the slab. The column ends were cut slope-normal (zoom top left in c). The coordinate system originates at the snow surface edge at the downslope side of the column. g is the gravity vector and θ = 37° indicates slope angle. Testing is done by using a snow saw to cut uphill into a pre-identified weak layer until the onset of unstable crack growth. Each experiment was recorded with high-speed cameras, either filming a close-up ( ≈ 0.6 m slope-parallel field of view, blue and red) or the full column length L (full-view).
