Dm. Mcclung et J. Schweizer, Skier triggering, snow temperatures and the stability index for dry-slab avalanche initiation, J GLACIOL, 45(150), 1999, pp. 190-200
For more than 30 years the quantitative method of evaluating stability (e.g
. Roch, 1966; Fohn, 1987; Jamieson, 1995; Jamieson and Johnston, 1998a.) ha
s been focused on calculation of a strength-to-load ratio (or stability ind
ex): when the shear stress applied to the weak layer reaches the shear stre
ngth, failure is imminent. However, field observations combined with experi
ence and measurements indicate that snow-slab temperatures and slab hardnes
s can have a strong influence on dry-snow slab stability. In this paper, we
present a simple static analysis of the stability index, and discuss the i
mportance of slab temperatures and hardness and macroscopic size effects (f
actors not: contained in the stability index) on snow-slab stability. Our c
onclusion is that the traditional method lacks some elements which are very
important in snow-slab stability, particularly when skier triggering is in
volved.