Volume 96, Number 5, December 2011
|Number of page(s)||5|
|Section||Geophysics, Astronomy and Astrophysics|
|Published online||24 November 2011|
Physical models of giant subaqueous rock avalanches
PHYFES - Oslo, Norway
Accepted: 18 October 2011
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.
PACS: 92.40.Ha – Debris flow and landslides / 83.80.Fg – Granular solids
© EPLA, 2011
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