The evolution of the western rift area of the Fimbul Ice Shelf, Antarctica 1Institute of Geophysics, KlimaCampus, University of Hamburg, Bundesstraße 55, 20146 Hamburg, Germany
24 Oct 2011
2Alfred Wegener Institute for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany
Received: 25 March 2011 – Published in The Cryosphere Discuss.: 11 April 2011 Abstract. This paper studies the evolution of a zone in the Fimbul Ice Shelf
that is characterised by large crevasses and rifts west of
Jutulstraumen, an outlet glacier flowing into Fimbulisen.
High-resolution radar imagery and radio echo sounding data were used
to study the surface and internal structure of this rift area and to
define zones of similar characteristics. The western rift area is
dominated by two factors: a small ice rumple that leads to basal
crevasses and disturbs the homogeneity of the ice, and a zone with
fibre-like blocks. Downstream of the rumple we found down-welling of
internal layers and local thinning, which we explain as a result of
basal crevasses due to the basal drag at the ice rumple. North of
Ahlmannryggen the ice loses its lateral constraint and forms
individual blocks, which are deformed like fibres under shear, where
the ice stream merges with slower moving ice masses of the western
side. There, the ice loses its integrity, which initiates the
western rift system. The velocity difference between the slow moving
western part and the fast moving extension of Jutulstraumen produces
shear stress that causes the rifts to form tails and expand them to
the major rifts of up to 30 km length.
Revised: 04 October 2011 – Accepted: 06 October 2011 – Published: 24 October 2011
Citation: Humbert, A. and Steinhage, D.: The evolution of the western rift area of the Fimbul Ice Shelf, Antarctica, The Cryosphere, 5, 931-944, doi:10.5194/tc-5-931-2011, 2011.