"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.


Contact
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.



Item Type
Conference (Conference paper)
Authors
Divisions
Primary Division
Programs
Primary Topic
Peer revision
Not peer-reviewed
Publication Status
Published
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 .


Download
[img]
Preview
PDF
IASC_NAG_2020_Obergurgl.pdf

Download (2MB) | Preview

Share

Research Platforms

Campaigns


Actions
Edit Item Edit Item