Abstract
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.
Highlights
Fimbulisen is an ice shelf fringing Dronning Maud Land, East Antarctica, located from 71.5◦ S to 69.5◦ S and 3◦ W to 7.5◦ E (Fig. 1)
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
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
Summary
Fimbulisen is an ice shelf fringing Dronning Maud Land, East Antarctica, located from 71.5◦ S to 69.5◦ S and 3◦ W to 7.5◦ E (Fig. 1). With a size of ∼ 39 400 km it is the largest ice shelf in the Hakon VII Sea. The ice stream Jutulstraumen, the largest outlet glacier in Dronning Maud Land, feeds the central part of the ice shelf. The ice stream Jutulstraumen, the largest outlet glacier in Dronning Maud Land, feeds the central part of the ice shelf The inflow of this fast ice stream (about 700 ma−1) divides the ice shelf into a fast and two slow moving parts and builds up an ice tongue at the calving front, the Trolltunga. This area covers a size of approximately 30 km width and 100 km length
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