Preprints
https://doi.org/10.5194/esurf-2021-10
https://doi.org/10.5194/esurf-2021-10

  09 Mar 2021

09 Mar 2021

Review status: this preprint is currently under review for the journal ESurf.

Permafrost in monitored unstable rock slopes in Norway – New insights from rock wall temperature monitoring, geophysical surveying and numerical modelling

Bernd Etzelmüller1, Justyna Czekirda1, Florence Magnin2, Pierre-Allain Duvillard2, Emmanuel Malet2, Ludo Ravanel2, Andreas Aspaas1,3, Lene Kristensen3, Ingrid Skrede3, Gudrun D. Majala3, Benjamin Jacobs4, Johannes Leinauer4, Christian Hauck6, Christin Hilbich6, Martina Böhme5, Reginald Hermanns5, Harald Ø. Eriksen7,8,a, Michael Krautblatter4, and Sebastian Westermann1 Bernd Etzelmüller et al.
  • 1Department of Geosciences, University of Oslo, Norway
  • 2EDYTEM Lab, Université Savoie Mont Blanc, CNRS, Le Bourget-du-Lac, France
  • 3Norwegian Water and Energy Directorate (NVE), Oslo, Norway
  • 4Technical University Munich, Germany
  • 5Department of Geosciences, University of Fribourg, Switzerland
  • 6Geological Survey of Norway (NGU), Trondheim, Norway
  • 7NORCE Norwegian Research Centre AS, Tromsø, Norway
  • 8Department of Geosciences, UiT-The Arctic University of Norway, Tromsø, Norway
  • acurrent employer: Multiconsult Norge AS, Tromsø, Norway

Abstract. The warming and subsequent degradation of mountain permafrost within alpine areas is an important process influencing the stability of steep slopes and rock faces. The unstable and monitored slopes of Mannen (Møre and Romsdal, southern Norway) and Gámanjunni-3 (Troms and Finnmark, northern Norway) were classified as high-risk sites by the Norwegian Geological Survey (NGU). Failure initiation has been suggested to be linked to permafrost degradation, but the detailed permafrost distribution at the sites is unknown. Rockwall (RW) temperature loggers at both sites have measured the thermal regime since 2015, showing mean rock surface temperatures between +2.5 °C and −1.6 °C depending on site and aspect. Between 2016 and 2019 we conducted 2D and 3D electrical resistivity tomography (ERT) surveys on the plateau and directly within the rock wall back scarp of the unstable slopes at both sites. In combination with geophysical laboratory analysis of rock wall samples from both sites, the ERT soundings indicate wide-spread permafrost areas, especially at Gámanjunni-3. Finally, we conducted 2D thermal modelling to evaluate the potential thermal regime. Rockwall temperatures, together with ERT measurements and modelling of the ground thermal regime strongly indicate, at least locally, the presence of permafrost. Displacement rates show a seasonality, with higher velocities during spring and early summer than the rest of the year, possibly related to snow melting.

Bernd Etzelmüller et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on esurf-2021-10', Louise M. Vick, 07 Jun 2021
  • RC2: 'Comment on esurf-2021-10', Oliver Sass, 12 Jun 2021

Bernd Etzelmüller et al.

Bernd Etzelmüller et al.

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