Evaluating the destabilization susceptibility of active rock glaciers in the {French} {Alps}

In this study, we propose a methodology to estimate the spatial distribution of destabilizing rock glaciers, with a focus on the French Alps. We mapped geomorphological features that can be typically found in cases of rock glacier destabilization (e.g. crevasses and scarps) using orthoimages taken from 2000 to 2013. A destabilization rating was assigned by taking into account the evolution of these mapped destabilization geomorphological features and by observing the surface deformation patterns of the rock glacier, also using the available orthoimages. This destabilization rating then served as input to model the occurrence of rock glacier destabilization in relation to terrain attributes and to spatially predict the susceptibility to destabilization at a regional scale. Significant evidence of destabilization could be observed in 46 rock glaciers, i.e. 10 % of the total active rock glaciers in the region. Based on our susceptibility model of destabilization occurrence, it was found that this phenomenon is more likely to occur in elevations around the 0 ◦C isotherm (2700–2900 m a.s.l.), on north-facing slopes, steep terrain (25 to 30◦) and flat to slightly convex topographies. Model performance was good (AUROC = 0.76), and the susceptibility map also performed well at reproducing observable patterns of destabilization. About 3 km2 of creeping permafrost, or 10 % of the surface occupied by active rock glaciers, had a high susceptibility to destabilization. Considering we observed that only half of these areas of creep are currently showing destabilization evidence, we suspect there is a high potential for future rock glacier destabilization within the French Alps.

Références

Title
Evaluating the destabilization susceptibility of active rock glaciers in the {French} {Alps}
Publication Type
Journal Article
Year of Publication
2019
Journal
The Cryosphere
Volume
13
Pagination
141–155
Date Published
jan
ISSN
1994-0424
Keywords
CNRS, Lautaret
Submitted on 21 October 2021