Meltwater from the surface of glaciers flows towards the glacier terminus at the glacier bed, either slowly through sediment or discrete pockets of water distributed over the glacier bed, or quickly through several-meter-scale large tunnels. The pattern of this drainage, its configuration, and its location are important as they dictate the speed at which glaciers flow and how glaciers erode the landscape. However, these features of glacier beds are notoriously difficult to observe and are therefore poorly understood.
By using seismic data recorded adjacent to a glacier in Alaska, University of Idaho graduate student Margot Vore, Tim Bartholomaus, and others found that we were able to identify both the evolution of subglacial conduits, and also whether subglacial water flowed through a single conduit (as has traditionally been expected) or through multiple conduits. We found that, as the subglacial water approached the terminus, the pressure gradient driving efficient water flow reduced, and the conduits branched. Vore was able to identify a specific spectral signature of each conduit within the seismic data.
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