Hydro-mechanical regulation of ice flow on Sermeq Kujalleq (Store Glacier), West Greenland

Samuel Doyle, Bryn Hubbard, Poul Christoffersen, Robert Law, Thomas Chudley, Duncan Hewitt, Jerome Neufeld, Charlotte M. Schoonman, Marion Bougamont

Allbwn ymchwil: Cyfraniad at gynhadleddPapur


Our knowledge of the relationship between subglacial hydrology and basal motion remains incomplete, particularly for fast-moving and soft-bedded outlet glaciers. To address this, we drilled and instrumented three boreholes to the bed at locations extending away from a suspected subglacial channel at a site 30 km from the terminus of Sermeq Kujalleq (Store Glacier), Greenland. We present detailed results from the analysis of borehole response tests and time series of subglacial water pressure, surface ice motion, surface melt, and supraglacial river discharge. These data reveal that the boreholes connected to both hydraulically-isolated and weakly-connected components of the subglacial drainage system. Measurements of the response of subglacial water pressure to the connection and drainage of adjacent water-filled boreholes provide evidence for gap opening at the ice-sediment interface, Darcian flow through the sediment layer, and the forcing of water pressure in a hydraulically-isolated cavity by elastic stress transfer. We observed a small pressure drop followed by a large pressure rise in response to the connection of an adjacent borehole, consistent with the propagation of a flexural wave through the ice and underlying deformable sediment. We interpret the delayed pressure rise as evidence of no pre-existing conduit and the subsequent progressive decrease in hydraulic transmissivity as the closure of a narrow (
Iaith wreiddiolSaesneg
StatwsCyhoeddwyd - 01 Rhag 2021

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