Evidence of Seasonal Uplift in the Argentière Glacier (Mont Blanc Area, France)

The hydromechanical processes by which basal water controls sliding at the glacier bed are poorly known, despite motion being responsible for a large part of ice flux in temperate alpine glaciers. Previous studies suggest that strongly relates to quantity stored ice-bedrock interface. However, this storage is difficult quantify accurately on basis surface-motion observations, given uplift can also be affected changes vertical-strain rates and velocity change. Here, we use comprehensive data set situ measurements performed over 2 years Argentière Glacier French Alps investigate relationships between horizontal vertical velocities, sliding, subglacial runoff separation. We observe strikingly uplifts varying spatially 0.20 0.90 m winter/spring seasons January June with consistent spatial pattern from 1 year another. show, based observations three dimensional ice-flow modeling, these cannot explained solely strain or up an inclined bed. Our results reveal more than 80% observed related enhanced separation through cavitation, allowing us estimate volume occupied water-filled cavities. interpretation mainly caused increased cavitation associated increase surface velocity. These findings provide important observational constraints testing hydrological models.