title: Frictional velocity-weakening in landslides on Earth and on other planetary bodies.
abstract: One of the ultimate goals in landslide hazard assessment is to predict maximum landslide extension and velocity. Despite much work, the physical processes governing energy dissipation during these natural granular flows remain uncertain. Field observations show that large landslides travel over unexpectedly long distances, suggesting low dissipation. Numerical simulations of landslides require a small friction coefficient to reproduce the extension of their deposits. Here, based on analytical and numerical solutions for granular flows constrained by remote-sensing observations, we develop a consistent method to estimate the effective friction coefficient of landslides. This method uses a constant basal friction coefficient that reproduces the first-order landslide properties. We show that friction decreases with increasing volume or, more fundamentally, with increasing sliding velocity. Inspired by frictional weakening mechanisms thought to operate during earthquakes, we propose an empirical velocity-weakening friction law under a unifying phenomenological framework applicable to small and large landslides observed on Earth and beyond.
authors.affiliation: 1] Équipe de sismologie, Institut de Physique du Globe de Paris, Sorbone Paris Cité, Université Paris Diderot, UMR 7154 CNRS, 1 rue Jussieu, 75238 Paris cedex 05, France [2] Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd, Pasadena, California 95125, USA [3] Present address: Laboratoire Astrophysique, Instrumentation et Modélisation (AIM), CNRS-UMR 7158, Université Paris-Diderot, CEA-Saclay, Gif-sur-Yvette 91191, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Lucas
authors.affiliation: 1] Équipe de sismologie, Institut de Physique du Globe de Paris, Sorbone Paris Cité, Université Paris Diderot, UMR 7154 CNRS, 1 rue Jussieu, 75238 Paris cedex 05, France [2] Équipe ANGE INRIA, Laboratoire Jacques-Louis Lions, UPMC Paris 6, 4 place Jussieu, Case 187 75252 Paris cedex 05, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Mangeney
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd, Pasadena, California 95125, USA.
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Ampuero