Is gravitational spreading a precursor for the Stífluhólar landslide (Skagafjörður, Northern Iceland)?

• Published in: Géomorphologie : relief, processus, environnement
• Main Authors: Coquin, Julien, Mercier, Denis, Bourgeois, Olivier, Feuillet, Thierry, Decaulne, Armelle
• Other Authors: Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Espaces, Nature et Culture (ENeC), Université Paris-Sorbonne (UP4)-Centre National de la Recherche Scientifique (CNRS), 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), Laboratoire Dynamiques Sociales et Recomposition des Espaces (LADYSS), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris 8 Vincennes-Saint-Denis (UP8)-Université Paris Nanterre (UPN)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: Landslide; Holocene; Paraglacial; Geomorphology; Iceland; [SHS.GEO]Humanities and Social Sciences/Geography; Skagafjörður
• Online Access: https://hal.archives-ouvertes.fr/hal-01318136; https://doi.org/10.4000/geomorphologie.11295

International audience In Iceland, the Late Weichselian deglaciation led to paraglacial topographic readjustments in the form of extensivedeep-seated gravitational slope deformation (DSGSD) and large rockslope failures (landslides and rock-avalanches).Here we provide age estimates for the Stí" uhólar landslide (Tröllaskagi Peninsula, Northern Central Iceland),which indicate that this occurred between the end of the Late Weichselian deglaciation (15-13 ka cal. yr. BP) and8200 ± 1400 cal. yr. BP. Our surface observations also suggest that the Stífluhólar landslide was probably initiatedby propagation and connection of DSGSD failure planes. This observation suggests that the DSGSD can act as aprecursor for landsliding in paraglacial settings. However, further investigations are still required to fully assess therole of DSGSD as a landslide precursor, both at the local and at a regional scale. Comparisons with other examplesof paraglacial rock slope failures in Northern Iceland and in the world suggest that DSGSD is not the main orsuficient precondition for large landslides. The landslide of Stífluhólar occurred due to some combination offavorable preconditioning, predisposing and triggering controls. Predisposing controls include: the favourable dipof the bedding planes in the basaltic bedrock and the presence of intercalated poorly cohesive layers of palagonitebetween the lava layers, probably acting as basal sliding planes for the landslide.