Abstract ID: 3.12066 | Accepted as Poster | Poster | TBA | TBA

Rock glaciers are well-known as visible landforms of creeping mountain permafrost. Studies over the last decades revealed a global and recent acceleration that correlates with the rise in air temperatures. However, its impact on degraded permafrost conditions has been studied in a lesser extent than those of active rock glaciers. Even fewer studies have explored the possibility of deactivated rock glaciers ‘reaching an active state’ (RGIK, 2023). However, 20% of transitional rock glaciers in the French Alps were found to exhibit speeds higher than expected.
In this poster, we aim to bring insights on the internal characteristics of three rock glaciers through a joint inversion of Electrical Resistivity Tomography (ERT) and Induced Polarization (IP) data in a comparative approach. Four longitudinal pseudo-sections will be presented for Lanserlia, Chanrouge (Vanoise massif) and Vieux Marinet (Ubaye massif) rock glaciers considering their differences in activity and dynamical characteristics.
First, the range of resistivity values varies significantly from one site to another. The interpretation of thick resistive layers could indicate the presence of a frozen core at all three sites, although the location, thickness, and homogeneity of these horizons differ. Chanrouge rock glacier has the thickest frozen core and this thickness decreases with elevation. Lanserlia exhibits distinct resistive horizons between the lower and higher areas, either between the two profiles where a thinner and smaller frozen layer is visible on one of them. Last, the Vieux Marinet rock glacier exhibits a thick and large discontinuous permafrost body. Neither high nor continuous resistive values are observed on the upper and active unit, where the presence of multiple conductive horizons are moreover present
This study contributes to a better understanding of the role of internal structure, particularly the presence of ice and water, in the motion of these landforms. The joint use of ERT and IP allows for better identification of different transitional trajectories ERT signatures. The IP data particularly provides additional insights into subsurface properties by helping to differentiate ice, water, and fine-grained sediments, thereby refining the hydrogeological interpretation.