"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.

• Main Authors: Smith, Emma C., Diez, Anja, Eisen, Olaf, Hofstede, Coen, Kohler, Jack
• Other Authors: Dunse, Thorben, van Pelt, Ward, Abermann, Jakob, Kuhn, Michael
• Format: Conference Object
• Language: unknown
• Published: IASC 2020
• Subjects: Arctic; Svalbard; Kongsfjord; Kongsvegen; glacier; IASC; Kongsfjord*
• Online Access: https://epic.awi.de/id/eprint/51701/; https://epic.awi.de/id/eprint/51701/1/IASC_NAG_2020_Obergurgl.pdf; https://nag.iasc.info/images/publications/abstracts/IASC_NAG_2020_Obergurgl.pdf; https://hdl.handle.net/10013/epic.b5d850c4-f6d1-4a8c-836a-3aca2f272158; https://hdl.handle.net/

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.