Ice-shelf fracture due to viscoelastic-flexure stress induced by fill/drain cycles of supraglacial lakes
MacAyeal, Douglas R
Cambridge University Press
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Banwell, A., & MacAyeal, D. R. (2015). Ice-shelf fracture due to viscoelastic-flexure stress induced by fill/drain cycles of supraglacial lakes. Antarctic Science, 27 587-597. https://doi.org/10.1017/S0954102015000292
Using a previously-derived treatment of viscoelastic flexure of floating ice shelves, we simulate multiple years of evolution of a single, axisymmetric supraglacial lake when it is subjected to annual fill/drain cycles. Our viscoelastic treatment follows the assumptions of the well-known thin-beam and thin-plate analysis but, crucially, also covers power-law creep rheology. As the ice-shelf surface does not completely return to its un-flexed position after a 1-year fill/drain cycle, the lake basin deepens with each successive cycle. This deepening process is significantly amplified when lake-bottom ablation is taken into account. We evaluate the time-scale over which a typical lake reaches a sufficient depth such that ice-shelf fracture can occur well beyond the lake itself in response to lake filling/drainage. We show that, although this is unlikely during one fill/drain cycle, fracture is possible after multiple years assuming surface meltwater availability is unlimited. This extended zone of potential fracture implies that flexural stresses in response to a single lake filling/drainage event can cause neighbouring lakes to drain, which, in turn, can cause lakes farther afield to drain. Such self-stimulating behaviour may have accounted for the sudden, widespread appearance of a fracture system that drove the Larsen B Ice Shelf to break-up in 2002.
ice-shelf instability, viscoelasticity, melt ponds, hydrofracture, Antarctica
Alison Banwell acknowledges the support of an Antarctic Science International Bursary from Antarctic Science Ltd. and a Bowring Junior Research Fellowship from St Catharine’s College, Cambridge.
External DOI: https://doi.org/10.1017/S0954102015000292
This record's URL: https://www.repository.cam.ac.uk/handle/1810/248979
Attribution-NonCommercial 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by-nc/2.0/uk/
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