Multi-temporal mapping of rock glacier displacements: insights from SfM, ALS and TLS high-resolution datasets on the Laurichard rock

• Main Authors: Bodin, Xavier, Sanchez, Olivier, Jaillet, Stéphane, Rabatel, Antoine, Thibert, Emmanuel
• Other Authors: Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), International Permafrost Association
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2016
• Subjects: [SDE]Environmental Sciences; Bodin; Ice; permafrost
• Online Access: https://sde.hal.science/hal-01887932

International audience The deformation of rock glaciers is a climate-dependent process which affects many mountain debris slopes underlain with ice-rich permafrost (Haeberli et al., 2006). Under temperate conditions, like in the Alps, the typical magnitude of movement is in the order of a few dm/a to 1-2 m/a (Barsch, 1996). However, recent measurements of accelerating rock glaciers show that velocity can increase up to several m/a (Delaloye et al., 2012). This kinematics variability can locally lead to slope instabilities and trigger hazardous phenomena: in France, the collapse of the Bérard rock glacier in 2006 (Bodin et al., 2016) and the debris-flow that started at the Lou rock glacier in 2015 (Paulhe et al., 2015) can be considered as two events that exemplify the possible impacts of permafrost degradation for human societies living in mountain territories. At the limit between the Northern and the Southern-more Mediterranean-influenced-French Alps, the Laurichard rock glacier benefits from a long-term monitoring since the early 80's (Francou & Reynaud, 1992). Using 30-year long annual geodetic surveys of blocks, we detected inter-annual fluctuations of velocity (Bodin et al., 2009), which synchronicity with many series on other surveyed rock glaciers in the Alps suggests that the atmospheric warming, modulated by the nivological conditions, is controlling the rock glacier deformation rates (Delaloye et al., 2012). Nevertheless the knowledge on the processes that govern such behavior is still lacking physical basis: a better understanding requires to model the geomechanics of rock glacier, and for that accurate multi-temporal maps of surface displacements are fundamental. For that purpose, we produced very high-resolution 3D models of the Laurichard rock glacier, acquired either by terrestrial laserscanning (TLS) in 2005, 2006, 2011 and 2013, airborne laserscanning (ALS) in 2012 and terrestrial photogrammetry (or structure-from-motion, SfM) in 2013 and 2015. The density of the generated point clouds we ...