Thesis: Toward a quantitative assessment of glacier stability from physical ice flow modeling: improving the prediction of glacier collapses M/F

Job Description

Thesis Subject

-------Ice avalanches associated with the collapse of glaciers are among the most dramatic hazards in mountainous areas (Kääb et al., 2021). Due to their large volume (several million cubic meters) and long reach (several kilometers), these events pose a significant threat to populated areas. However, predicting glacier collapse remains difficult, and it is not currently possible to assess quantitatively which glaciers have the potential to collapse. In this context, physical ice flow modeling could be used to evaluate the current and future stability of specific glaciers in order to determine whether in-situ monitoring should be deployed for early warning systems. Modeling glacier collapse requires the detailed description of evolving temperature, basal friction, ice fracture and stress field in realistic three-dimensional geometries. Our research group has been working toward such a model by developing the Elmer/Ice finite element code, which includes most of the processes relevant to modeling glacier collapse. The code has been used to estimate the future temperature changes of hanging glaciers (Gilbert et al., 2015) and to reanalyze remarkable previous glacier collapses, such as those of the Aru Glaciers in Tibet (Gilbert et al., 2018) and the Birch Glacier in Switzerland (Brondex et al., in prep). These studies highlight the importance of interactions between the frozen and thawed basal parts of a glacier in shaping it towards an unstable state, and how multi-scale bed roughness controls the redistribution of stresses following a perturbation, thus determining the glacier's ability to maintain the global force balance. However, several unknown factors, especially in the value of critical material parameters, remain to be resolved in order to reach a reliable estimate of the potential for glacier collapse. In particular, an accurate description of how stress concentration damages the ice until failure is missing and should be constrained by natural scale observations. In addition, the frictional changes that occur during the transition from a frozen to a thawed ice-rock interface are poorly understood, yet are critical to evaluating the stability of glaciers in a warming climate.
The aim of this PhD project is to develop a numerical tool that can predict glacier collapse by constraining unknown material parameters through the reanalysis of several observed past collapses. The research will focus on developing realistic failure criteria within the ice body, as well as an accurate representation of the transient frictional changes that occur at the bed in response to progressive thermal changes or sudden perturbations linked to rise in water pressure or external loading (e.g. rockfall). Past collapses will allow the PhD candidate to focus on different aspects that need to be constrained: (1) the Aru (Gilbert et al., 2018) and Marmolada (Bondesan & Francese, 2023) Glaciers for the damage and failure criteria in cold ice, (2) the Altels Galcier (Faillettaz et al., 2011) for frictional changes associated with bed thawing and (3) the Tour and Allalin Glaciers (Faillettaz et al., 2012) for frictional changes associated with a rise in water pressure in temperate glaciers. The work carried out in this thesis will build on the current thermo-mechanical model developed at IGE and based on the finite element code Elmer/ice. Ultimately, a criterion based on the ice damage and stress state will be developed to determine a stability index, which will provide a quantitative estimate of glacier stability. This approach will then be used to assess the stability of glaciers that are currently being monitored and suspected to collapse in the future.
This PhD is part of 5-years program founded by the Plan d'Action pour la Prévention des Risques d'Origine Glaciaire (PAPROG) with the overarching goal to develop an operational modeling tool for glacier hazard prediction and analysis. This PhD will benefit from technical support funded by the project and collaborations within the PAPROG team.

Your Work Environment

The Institute of Environmental Geosciences (IGE) is a public research laboratory affiliated with the CNRS, the IRD, the University of Grenoble Alpes (UGA), and Grenoble-INP. Its research focuses on climate change and the impact of human activities on our planet in polar, mountainous, and intertropical regions—areas that are particularly sensitive to major societal challenges.
The laboratory has an average staff of approximately 330 people, including 190 permanent employees (researchers, faculty members, engineers, technicians, and administrative staff) and about 140 doctoral students, postdoctoral researchers, and contract employees. Each year, the IGE also hosts approximately 120 interns and visiting scientists. The IGE is spread across four buildings on the Grenoble university campus (the Glaciology Building, OSUG-B, the House of Climate and the Planet, and INRAE-Grenoble in Saint-Martin-d'Hères).
The IGE is one of the main laboratories of the Grenoble Observatory of Universe Sciences (OSUG), a federative structure of the National Institute of Universe Sciences (INSU).
The IGE actively contributes to the national research strategy in the polar regions, in collaboration with national and international partners. It participates in numerous national and international projects.
The successful candidate will carry out their duties within the IGE's Cryodyn team, as part of the PAPROG project, under the supervision of Olivier Gagliardini.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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