Spatial and temporal variability of surface deformation in a paraglacial alpine environment measured from satellite radars

Using satellite radar interferometry, we investigate surface deformation in the Great Aletsch Glacier region from 2015 to 2021. By applying a statistical blind source separation method on displacement timeseries, our study reveals irreversible trends near large slope instabilities, potentially indicating slope responses to the glacier’s retreat. Moreover, annual cyclic deformation indicates significant pore pressure variations in fractured bedrock slopes resulting from groundwater storage and discharge processes. These spatial variations, assessed with satellite radars, reflect changes in pore pressure and rock mass hydromechanical properties, aligning with continuous ground monitoring data. This study demonstrates the potential of using satellite interferometry to investigate slope-scale mechanical processes driven by seasonal to multiannual environmental factors in complex alpine regions. It is the first timeseries synthetic aperture radar (TS-InSAR) study in a paraglacial environment validated by spatially distributed, high-resolution ground monitoring data. Moreover, it shows the advantages of the TS-InSAR high spatial coverage and its capacity to complement ground monitoring during data interruptions at ground stations. Combining satellite data with ground-based measurements and coherent structural hypotheses opens new possibilities for studying similarly remote and less instrumented regions. • Statistical signal decomposition for displacement timeseries in complex environment. • Satellites map irreversible long-term damage of stable and unstable slopes. • Spatial variations of reversible deformation are linked to pore pressure change. • Local groundwater recharge deformation patterns are discernible from satellites.