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Nature, vol 395, 1998, 771-774.
Hydrological characteristics of the drainage system beneath a surging glacier
Helgi Björnsson
Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik, Iceland
A unique combination of natural circumstances allows us to assess current theories about water
flow beneath glaciers. Outburst floods from the subglacial lake, Grímsvötn, have taken place before,
during and subsequent to surging of Skeiđarárjökull, the glacier beneath which they drain. The observable
drainage patterns associated with these floods show the different nature of the basal water conduit
system of the glacier during surge and non-surge phases. During surge, basal water is dispersed slowly
across the bed in a distributed drainage system; but when the glacier is not surging, water is transported
rapidly through a system of tunnels.