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UBC Theses and Dissertations

Modelling the propagation of crevasses and calving in ice shelves Zarrinderakht, Maryam


Ice shelves are floating extensions of glaciers and ice sheets that terminate in the ocean, and their stability and mass balance play a crucial role in controlling the sea level. One of the major processes affecting their stability is the calving of icebergs, which is a complex and poorly understood phenomenon. In order to understand and predict the mass balance of ice shelves, it is essential to investigate the physical processes that control iceberg calving. Despite the challenging nature of this problem, due to the lack of observational data and the mathematical and numerical difficulties involved in modeling crevasses penetration, this topic remains of great scientific and practical importance. This Ph.D. thesis focuses on the investigation of the fundamental parameters that influence crack growth and, as a result, the rate of iceberg calving. The study considers the effect of hydrological parameters, such as water table height, as well as geometry aspect ratio, basal and surface crevasse positions, and ice shelf extensional forcing. The research begins with the assumption of ice as an elastic medium with abrupt crevasse penetration, and progresses to a more advanced visco-elastic model that accounts for gradual changes in parameters. The model is compared to several recent related models and the advantages and disadvantages of each approach are discussed. The findings of this study reveal that the purely instantaneous stress-based calving laws that have become popular in large-scale ice sheet mechanics are too simplistic to accurately describe the complex process of iceberg calving. Instead, the study proposes a more comprehensive approach that takes into account the interplay between multiple parameters and their gradual changes over time. In conclusion, this Ph.D. thesis provides a valuable contribution to the field of stability of ice shelves by investigating the physical processes that control iceberg calving. The results of this research will inform and support the efforts to better understand and predict the behavior of crevasses on ice shelves, and their indirect impact on global sea level.

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