Physical models of giant subaqueous rock avalanches

Large subaqueous rock avalanches are characterized by horizontal run-outs approximately ten times longer than the fall height. It is shown that this mobility is somehow puzzling, as it corresponds to a decrease of the effective friction coefficient by a factor 10–50 compared to bare rock. Two dynami...

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Bibliographic Details
Published in:Europhysics letters 2011-12, Vol.96 (5), p.59004
Main Author: De Blasio, F. V
Format: Article
Language:English
Subjects:
83.80.Fg
92.40.Ha
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Summary:Large subaqueous rock avalanches are characterized by horizontal run-outs approximately ten times longer than the fall height. It is shown that this mobility is somehow puzzling, as it corresponds to a decrease of the effective friction coefficient by a factor 10–50 compared to bare rock. Two dynamical models are so introduced to explain the observed mobility. In the first model, the fast-moving fragmented rock avalanche is subjected to a lift force that makes it hydroplane, avoiding contact with the sea floor. In a second model the fragmented material ingests water, transforming into a non-Newtonian fluid that progressively reduces its shear strength. Both models give peak velocity of 65–70 m/s, which implies a high potential for tsunami generation.
ISSN:0295-5075
1286-4854
DOI:10.1209/0295-5075/96/59004