Soft sediment deformation in the shallow submarine slope off Nice (France) as a result of a variably charged Pliocene aquifer and mass wasting processes
Autor: | Pierre Henry, Achim J Kopf, Sylvia Stegmann, Simon Haas, Bernard Dennielou, Kai-Christian Weber, Sebastien Garziglia |
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Přispěvatelé: | Center for Marine Environmental Sciences [Bremen] (MARUM), Universität Bremen, Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA) |
Jazyk: | angličtina |
Rok vydání: | 2016 |
Předmět: |
010504 meteorology & atmospheric sciences
Stratigraphy Geochemistry Submarine landslide Sediment [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Geology Landslide Mass wasting Silt 010502 geochemistry & geophysics 01 natural sciences Deposition (geology) Soft sediment deformation Weak zone Slope stability Facies Fluidisation Geomorphology ComputingMilieux_MISCELLANEOUS 0105 earth and related environmental sciences |
Zdroj: | Sedimentary Geology Sedimentary Geology, Elsevier, 2016, 344, pp.290-309. ⟨10.1016/j.sedgeo.2016.05.014⟩ Sedimentary Geology (0037-0738) (Elsevier Science Bv), 2016-10, Vol. 344, P. 290-309 Sedimentary Geology, Elsevier, 2016, 344 (SI), pp.290-309. ⟨10.1016/j.sedgeo.2016.05.014⟩ Sedimentary Geology, 2016, 344 (SI), pp.290-309. ⟨10.1016/j.sedgeo.2016.05.014⟩ |
ISSN: | 0037-0738 |
Popis: | International audience; Along the Ligurian slope near Nice, southeastern France, a combination of natural and man-made factors govern slope stability, and contributed to a devastating tsunamigenic landslide near Nice airport in 1979. Based on a total of 72 gravity and Kullenberg cores we characterise the architecture and facies of the subbottom sediment. A total of six sedimentary fades types were observed, three of which represent the Pliocene-Holocene background sediment in the wider Nice area while another three are associated with the 1979 landslide and tsunami. The three primary facies types are soft silty clay/clayey silt, somewhat indurated silt/sand interbeds, and Pliocene conglomerates underlying the former. The three other facies are poorly sorted mass wasting deposits up to pebble size, silt representing the finer fraction of the mobilised mass, and a tsunami-related bed into which plant debris and artefacts got amalgamated. Accompanying geotechnical results attest that significant strength variations exist when comparing measurements from the narrow shelf, shelf break and shallow slope as well as the 1979 slide scar. Factors such as groundwater charging in the more permeable horizons further lower the effective stress and, in places, approach lithostatic. Above such permeable silt/sand beds, deformation of soft clay is observed, suggesting that leaching of ions from the clay mineral surfaces and frayed edges also facilitates weakening and creep, micro slumping and folding. Elevated water supply as well as hydraulic fracturing of the clayey sediment is further attested by pipes of cm-diameter and several decimeters length, which entrained very soupy mud. In the shallowmost deposits in and landward of the slide scar, we also observe remnants from the catastrophic deposition associated with the 2-3 m high tsunami wave triggered in 1979, as attested by amalgamated sea grass and artefacts. Based on our observations and measurements on core-scale and earlier models based on in situ CPTu, we suggest that a significant part of the Quaternary delta and slope apron deposits are prone to being mobilised without a large external trigger, so that all in all a high risk for a landslide event of considerable size off Nice international airport is identified. (C) 2016 Elsevier B.V. All rights reserved. |
Databáze: | OpenAIRE |
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