Molards as an indicator of permafrost degradation and landslide processes

• Published in: Earth and Planetary Science Letters
• Main Authors: Morino, Costanza, Conway, Susan, Sæmundsson, Þorsteinn, Kristinn Helgason, Jón, Hillier, John, Butcher, Frances, Balme, Matthew, Jordan, Colm, Argles, Tom
• Other Authors: The Open University Milton Keynes (OU), Laboratoire de Planétologie et Géodynamique UMR 6112 (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Iceland Reykjavik, Icelandic Meteorological Office (IMO), Loughborough University, School of Physical Sciences Milton Keynes, Faculty of Science, Technology, Engineering and Mathematics Milton Keynes, The Open University Milton Keynes (OU)-The Open University Milton Keynes (OU), British Geological Survey Keyworth, British Geological Survey (BGS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: permafrost; landslide; Iceland; Mars; molards; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; Ice
• Online Access: https://hal.archives-ouvertes.fr/hal-02268386; https://hal.archives-ouvertes.fr/hal-02268386/document; https://hal.archives-ouvertes.fr/hal-02268386/file/HAL_Morino_etal_EPSL_2019.pdf; https://doi.org/10.1016/j.epsl.2019.03.040

International audience Molards have been defined in the past as conical mounds of debris that can form part of a landslide's deposits. We present the first conclusive evidence that molards in permafrost terrains are cones of loose debris that result from thawing of frozen blocks of ice-rich sediments mobilised by a landslide, and hence propose a rigorous definition of this landform in permafrost environments. We show that molards can be used as an indicator of permafrost degradation, and that their morphometry and spatial distribution give valuable insights into landslide dynamics in permafrost environments. We demonstrate that molards are readily recognisable not only in the field, but also in remote sensing data; surveys of historic aerial imagery allow the recognition of relict molards, which can be used as an indicator of current and past permafrost conditions. The triggering of landslides as a result of permafrost degradation will arguably occur more often as global atmospheric temperatures increase, so molards should be added to our armoury for tracking climate change, as well as helping us to understand landslide-related hazards. Finally, we have also identified candidate molards on Mars, so molards can inform about landscape evolution on Earth and other planetary bodies