"Basal conditions of Kongsvegen at the onset of surge - revealed using seismic vibroseis surveys" in the IASC Workshop on the dynamics and mass budget of Arctic glaciers - Abstracts and program booklet.


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emma.smith [ at ] awi.de

Abstract

Kongsvegen is a well-studied surge-type glacier in the Kongsfjord area of northwest Svalbard. Long-term monitoring has shown that the ice surface velocity has been increasing for the past 4 years; presenting a unique opportunity to study the internal ice structure, basal conditions and thermal regime that play a crucial role in initiating glacier surges. In April 2019, three-component seismic vibroseis surveys were conducted at two sites on the glacier, using a small Electrodynamic Vibrator source (ElViS). Site 1 is in the ablation area and site 2 near the equilibrium line, where the greatest increase in ice surface velocity has been observed. Initial analysis indicates the conditions at the two sites are significantly different. At site 1 the ice is around 220 m thick, sitting on a relatively flat and uniform bed, with no clear change in the bed reflection along the profile. There is a horizontally layered sediment package ∼60 m thick underlaying the bed. The ice column shows no internal layering. By contrast at site 2 (Fig. 1), where the ice is around 390 m thick, there is much more complex internal ice structure. Clear internal ice reflections are visible between 150-250 m depth – where we expect a transition from cold to temperate ice. Further reflections in the 100 m above the bed indicate there could be shearing or sediment entrainment in this area. Below the bed, cross-cutting layers are clearly visible and the bed reflection itself shows changing reflection polarity – suggesting water or very wet sediment is present in some areas. This suggests ice movement by basal sliding and shearing is likely.



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Event Details
IASC Workshop on the dynamics and mass budget of Arctic glaciers, 28 Jan 2020 - 30 Jan 2020, Obergurgl, Austria.
Eprint ID
51701
Cite as
Smith, E. C. , Diez, A. , Eisen, O. , Hofstede, C. and Kohler, J. (2020): "Basal conditions of Kongsvegen at the onset of surge - revealed using seismic vibroseis surveys" in the IASC Workshop on the dynamics and mass budget of Arctic glaciers - Abstracts and program booklet. / T. Dunse , W. van Pelt , J. Abermann and M. Kuhn (editors) , IASC Workshop on the dynamics and mass budget of Arctic glaciers, Obergurgl, Austria, 28 January 2020 - 30 January 2020 .


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