Gravity surveys for mountain permafrost quantification: the Sadole Rock Glacier (Italy)

Rock glaciers are permafrost landforms typical of high-altitude mountain environments, composed of varying proportions of ice, rock debris, air, and occasionally liquid water. Their internal structure is highly heterogeneous and evolves in response to climatic, hydrological, and geological forcing. Due to global warming, the investigation of mountain permafrost has become increasingly important for evaluating its stability, ice content, and hydrology. In this context, non-invasive geophysical techniques have proven to be effective tools for imaging subsurface conditions in periglacial environments.

The Sadole Rock glacier, located in the Eastern Italian Alps, has been extensively studied in the last years through several geophysical campaigns. In this study, we present the results of a complementary gravity investigation performed along two quasi-parallel profiles, with the aim of estimating the ice fraction in the permafrost and its spatial distribution. Data were collected between October 2024 and June 2025 using a relative gravimeter Scintrex CG-5 and were processed to finally obtain the complete Bouguer anomaly (BAC) along the profiles. BAC data show negative values, that we assume being related to the presence of ice. 2D forward modelling was carried out considering different scenarios. In all the cases examined, the bedrock depth was set based on preliminary geophysical information, while permafrost densities were varied as a function of the ice content considered.

The obtained results show the potential of gravity anomaly data for the estimation of the ice fraction of mountain permafrost. However, preliminary information is needed to constrain the density model (such as a resistivity model derived from ERT measurements), due to the high degree of non-uniqueness of the solution.