Abstract
The calving of icebergs from large Antarctic ice shelves is controlled mainly by the formation and propagation of rifts originating from the side margins of the ice shelf and local areas of grounding. Using InSAR, we observe the evolution of rifts along Hemmen Ice Rise, on Ronne Ice Shelf, Antarctica prior to the large calving event of October 1998. We couple these observations with a computer model combining the viscous flow of an ice shelf with a linear elastic fracture mechanics description of the propagation of rifts. The model reveals that the ice melange trapped in between the rifts exerts a major control on the propagation of rifts, and in turn on ice shelf stability. Melting of the ice melange from oceanic or atmospheric warming would significantly increase the propagation rate of rifts and threaten the ice‐shelf stability.
Highlights
[2] Large Antarctic ice shelves discharge ice into the oceans mainly from the calving of large tabular icebergs
[3] Here, we present a model describing the evolution of rifts near Hemmen Ice Rise (HIR), on the Ronne Ice Shelf, Antarctica, prior to the large calving event of October 1998 which resulted in the formation of iceberg A38
[4] We previously showed that the propagation of rifts in an ice shelf is well described by LEFM [Larour et al, 2004]
Summary
[2] Large Antarctic ice shelves discharge ice into the oceans mainly from the calving of large tabular icebergs. These icebergs form when the ice shelf ruptures, typically along lines of pre-existing weaknesses or rifts, which are fractures that penetrate through the entire ice column thickness. Rifts originate from thickness cracks in regions of high stress, such as the ice shelf side margins, ice rises, or in areas of intense longitudinal stretching of the ice [Vaughan, 1993; Weertman, 1973; Van der Veen, 1998]. [3] Here, we present a model describing the evolution of rifts near Hemmen Ice Rise (HIR), on the Ronne Ice Shelf, Antarctica, prior to the large calving event of October 1998 which resulted in the formation of iceberg A38.
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