Starving avalanches: Frictional mechanisms at the tails of finite-sized mass movements

The tail of an avalanche is characterized by diminishing flow heights. The decreasing flow heights are due to increased friction and therefore tails are ideally suited to investigate frictional mechanisms in avalanches. Using chute experiments with granular material, we observe two properties of ava...

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Bibliographic Details
Published in:Geophysical research letters 2007-10, Vol.34 (20), p.n/a
Main Authors: Bartelt, P., Buser, O., Platzer, K.
Format: Article
Language:English
Subjects:
avalanches
Earth sciences
Earth, ocean, space
energy
entrainment
Exact sciences and technology
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Summary:The tail of an avalanche is characterized by diminishing flow heights. The decreasing flow heights are due to increased friction and therefore tails are ideally suited to investigate frictional mechanisms in avalanches. Using chute experiments with granular material, we observe two properties of avalanche tails: (1) Coulomb friction μ increases in proportion to the decrease in the gravitational work rate g; (2) flow heights h are proportional to the square of the basal slip velocity u0; h ∝ u02. Another non‐steady region can be observed at the front of the avalanche. Although this region is shorter than the tail, we were able to detect a hysteresis of the friction μ coefficient as a function of the gravitational work rate. This fact indicates a time dependence of the frictional mechanisms. The results explain why avalanches starve when they are not fed by the intake of additional material at the front.
ISSN:0094-8276
1944-8007
DOI:10.1029/2007GL031352