Seismic monitoring of rock glaciers : towards understanding an emerging risk
Within mountain permafrost regions, rock glaciers refer to periglacial formations composed of a mixture of rock debris of varying size and frozen materials at depth. Among them, active rock glaciers exhibit surface displacement velocities of the order of m/year, reflecting deep-seated deformation dy...
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ftunigrenoble:oai:HAL:tel-03094893v1 2024-04-28T08:23:55+00:00 Seismic monitoring of rock glaciers : towards understanding an emerging risk Surveillance sismologique des glaciers rocheux : pour mieux contraindre un risque émergent Guillemot, Antoine Institut des Sciences de la Terre (ISTerre) Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA) Université Grenoble Alpes 2020-. Laurent Baillet Agnes Helmstetter Eric Larose 2020-09-29 https://theses.hal.science/tel-03094893 https://theses.hal.science/tel-03094893/document https://theses.hal.science/tel-03094893/file/GUILLEMOT_2020_diffusion.pdf fr fre HAL CCSD NNT: 2020GRALU020 tel-03094893 https://theses.hal.science/tel-03094893 https://theses.hal.science/tel-03094893/document https://theses.hal.science/tel-03094893/file/GUILLEMOT_2020_diffusion.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-03094893 Glaciologie. Université Grenoble Alpes [2020-.], 2020. Français. ⟨NNT : 2020GRALU020⟩ Noise Seismology Resonance frequency Bruit de fond Sismologie Fréquence de résonance Éléments finis [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology info:eu-repo/semantics/doctoralThesis Theses 2020 ftunigrenoble 2024-04-18T03:23:12Z Within mountain permafrost regions, rock glaciers refer to periglacial formations composed of a mixture of rock debris of varying size and frozen materials at depth. Among them, active rock glaciers exhibit surface displacement velocities of the order of m/year, reflecting deep-seated deformation dynamics governed by thermo-hydro-mechanical processes. Thus, their contribution to the sediment transfer that can be mobilized in torrential flows may be substantial, as well as the emerging natural risks linked to their destabilization. In support of kinematic monitoring, geotechnical and geophysical methods can be used to investigate a rock glacier at depth, but remain punctual and discontinuous. On the other hand, environmental seismology methods, already applied to landslide monitoring, allow continuous seismic recordings, reporting the state of the subsurface; the aim of this thesis is therefore to apply these passive seismic techniques to the monitoring of rock glaciers.Two active sites have thus been instrumented for several years: the Gugla rock glacier (Valais, Switzerland) and the Laurichard rock glacier (Hautes-Alpes, France). Several methods were applied to these seismic data: ambient noise correlation, microseismicity and spectral analysis. In general, the relative variation of the surface wave velocity (dv/v) shows significant seasonal variations: it reaches a maximum at the end of winter, before dropping during spring melt and reaching a minimum in summer. Similarly, the resonance frequencies specific to rock glaciers, that have been picked within the spectral content of the seismic ambient noise, follow the same seasonal pattern. We interpret these observations as the effect of freeze-thawing processes on the averaged stiffness of the rock glacier.In order to model the variation in the elastic parameters of the medium due to this freezing process, we used a three-phase Biot-Gassmann poroelastic model, considering the rock glacier as a solid porous matrix with pores filled with liquid water or ice. The ... Doctoral or Postdoctoral Thesis Ice permafrost Université Grenoble Alpes: HAL |
institution |
Open Polar |
collection |
Université Grenoble Alpes: HAL |
op_collection_id |
ftunigrenoble |
language |
French |
topic |
Noise Seismology Resonance frequency Bruit de fond Sismologie Fréquence de résonance Éléments finis [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology |
spellingShingle |
Noise Seismology Resonance frequency Bruit de fond Sismologie Fréquence de résonance Éléments finis [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology Guillemot, Antoine Seismic monitoring of rock glaciers : towards understanding an emerging risk |
topic_facet |
Noise Seismology Resonance frequency Bruit de fond Sismologie Fréquence de résonance Éléments finis [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology |
description |
Within mountain permafrost regions, rock glaciers refer to periglacial formations composed of a mixture of rock debris of varying size and frozen materials at depth. Among them, active rock glaciers exhibit surface displacement velocities of the order of m/year, reflecting deep-seated deformation dynamics governed by thermo-hydro-mechanical processes. Thus, their contribution to the sediment transfer that can be mobilized in torrential flows may be substantial, as well as the emerging natural risks linked to their destabilization. In support of kinematic monitoring, geotechnical and geophysical methods can be used to investigate a rock glacier at depth, but remain punctual and discontinuous. On the other hand, environmental seismology methods, already applied to landslide monitoring, allow continuous seismic recordings, reporting the state of the subsurface; the aim of this thesis is therefore to apply these passive seismic techniques to the monitoring of rock glaciers.Two active sites have thus been instrumented for several years: the Gugla rock glacier (Valais, Switzerland) and the Laurichard rock glacier (Hautes-Alpes, France). Several methods were applied to these seismic data: ambient noise correlation, microseismicity and spectral analysis. In general, the relative variation of the surface wave velocity (dv/v) shows significant seasonal variations: it reaches a maximum at the end of winter, before dropping during spring melt and reaching a minimum in summer. Similarly, the resonance frequencies specific to rock glaciers, that have been picked within the spectral content of the seismic ambient noise, follow the same seasonal pattern. We interpret these observations as the effect of freeze-thawing processes on the averaged stiffness of the rock glacier.In order to model the variation in the elastic parameters of the medium due to this freezing process, we used a three-phase Biot-Gassmann poroelastic model, considering the rock glacier as a solid porous matrix with pores filled with liquid water or ice. The ... |
author2 |
Institut des Sciences de la Terre (ISTerre) Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA) Université Grenoble Alpes 2020-. Laurent Baillet Agnes Helmstetter Eric Larose |
format |
Doctoral or Postdoctoral Thesis |
author |
Guillemot, Antoine |
author_facet |
Guillemot, Antoine |
author_sort |
Guillemot, Antoine |
title |
Seismic monitoring of rock glaciers : towards understanding an emerging risk |
title_short |
Seismic monitoring of rock glaciers : towards understanding an emerging risk |
title_full |
Seismic monitoring of rock glaciers : towards understanding an emerging risk |
title_fullStr |
Seismic monitoring of rock glaciers : towards understanding an emerging risk |
title_full_unstemmed |
Seismic monitoring of rock glaciers : towards understanding an emerging risk |
title_sort |
seismic monitoring of rock glaciers : towards understanding an emerging risk |
publisher |
HAL CCSD |
publishDate |
2020 |
url |
https://theses.hal.science/tel-03094893 https://theses.hal.science/tel-03094893/document https://theses.hal.science/tel-03094893/file/GUILLEMOT_2020_diffusion.pdf |
genre |
Ice permafrost |
genre_facet |
Ice permafrost |
op_source |
https://theses.hal.science/tel-03094893 Glaciologie. Université Grenoble Alpes [2020-.], 2020. Français. ⟨NNT : 2020GRALU020⟩ |
op_relation |
NNT: 2020GRALU020 tel-03094893 https://theses.hal.science/tel-03094893 https://theses.hal.science/tel-03094893/document https://theses.hal.science/tel-03094893/file/GUILLEMOT_2020_diffusion.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1797584528386031616 |