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Méthodes sismologiques pour l'étude de la fracturation dans les glaciers alpins : glaciers d'Argentière et du Gorner

Abstract : Alpine glaciers' motion results from a number of complex mechanisms involving hydrology, mechanics and thermodynamics on microscopic to kilometre-sized scales. Fracturing can be linked with a wide variety of causes : basal friction, opening of crevasses, variations in temperature (thermo-fracturing), changes in water pressure (hydro-fracturing). Previous studies showed that fracturing generated seismic waves that could be recorded using seismometers. Passive seismic studies therefore allow for probing the in situ mechanical properties of a glacier.
In this work, we intend to apply new seismological methods the study and characterize fracturing processes in alpine glaciers. To this effect, we focused on two specific sites (Glacier d'Argentière, Mont-Blanc, France, and Gornergletscher, Valais, Switzerland). Source location was performed using array techniques. Within this framework, we developed a grid-search method that is well suited for such sites. This method yields the whole hypocenter probability density function. It allowed us to bring to light a clustered seismic activity on glacier d'Argentière. In this specific case, events' local magnitude could be determined. We also showed that deep events recorded on the Gornergletscher were located nearby the ice - rock interface. In the same way, other techniques (noise correlation, beamforming) allowed us to enhance the information already obtained via the exhaustive grid-search method.
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https://tel.archives-ouvertes.fr/tel-00275319
Contributor : Pierre-François Roux <>
Submitted on : Wednesday, April 23, 2008 - 12:16:39 PM
Last modification on : Thursday, November 19, 2020 - 3:54:28 PM
Long-term archiving on: : Friday, September 28, 2012 - 1:00:13 PM

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  • HAL Id : tel-00275319, version 1

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Pierre-François Roux. Méthodes sismologiques pour l'étude de la fracturation dans les glaciers alpins : glaciers d'Argentière et du Gorner. Géophysique [physics.geo-ph]. Université de Savoie, 2008. Français. ⟨tel-00275319⟩

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