Evaluation of the criticality of cracks in ice shelves using finite element simulations

Plate, Carolin; Müller, Ralf; Humbert, Angelika; Groß, Dietmar

doi:10.5194/tcd-6-469-2012

Cited by 7 publications

(9 citation statements)

References 27 publications

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“…Our model does not simulate crack propagation, which as hypothesized in Weertman [, ], van der Veen [], Rist et al [], Plate et al [], and as observed in Fricker et al [], and Bassis et al [, , ] on the rifts of the Amery Ice Shelf, is controlled by the elastic stress regime at the rupture tip. However, propagation models for rifts and faults are preconditioned by the creep stress distribution, which is then applied as a load to the linear elastic stress regime near the rupture tip [ van der Veen , ; Larour et al , ; Hulbe et al , ; Plate et al , ]. As such, our model is well suited for this type of loading, as it takes into account the presence of cracks and the way they impact the background stress of the ice shelf.…”

Section: Discussionmentioning

confidence: 92%

“…As such, our model is well suited for this type of loading, as it takes into account the presence of cracks and the way they impact the background stress of the ice shelf. In models such as van der Veen [] or Plate et al [], the longitudinal stress applied to the rift flanks is taken equal to the background stress in which the crack is propagating. Such background stresses should therefore take into account the presence of the crack itself, which our model does.…”

Section: Discussionmentioning

confidence: 99%

“…Similar analysis by Weertman [] showed that bottom crevasses can also form, requiring a much lower background longitudinal stress in order to develop and propagate upward, due to the significantly higher water pressure at the ice/ocean interface. More recently, this type of analysis has been revisited using Linear Elastic Fracture Mechanics (LEFM) in order to better understand the impact of stress on crack initiation and propagation [ van der Veen , ; Rist et al , ; Plate et al , ]. Background stress is a result of the creeping of ice under its own weight and is therefore difficult to reconcile with an elastic stress regime near the rupture tip.…”

Section: Introductionmentioning

confidence: 99%

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Representation of sharp rifts and faults mechanics in modeling ice shelf flow dynamics: Application to Brunt/Stancomb‐Wills Ice Shelf, Antarctica

et al. 2014

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Ice shelves play a major role in buttressing ice sheet flow into the ocean, hence the importance of accurate numerical modeling of their stress regime. Commonly used ice flow models assume a continuous medium and are therefore complicated by the presence of rupture features (crevasses, rifts, and faults) that significantly affect the overall flow patterns. Here we apply contact mechanics and penalty methods to develop a new ice shelf flow model that captures the impact of rifts and faults on the rheology and stress distribution of ice shelves. The model achieves a best fit solution to satellite observations of ice shelf velocities to infer the following: (1) a spatial distribution of contact and friction points along detected faults and rifts, (2) a more realistic spatial pattern of ice shelf rheology, and (3) a better representation of the stress balance in the immediate vicinity of faults and rifts. Thus, applying the model to the Brunt/Stancomb-Wills Ice Shelf, Antarctica, we quantify the state of friction inside faults and the opening rates of rifts and obtain an ice shelf rheology that remains relatively constant everywhere else on the ice shelf. We further demonstrate that better stress representation has widespread application in examining aspects affecting ice shelf structure and dynamics including the extent of ice mélange in rifts and the change in fracture configurations. All are major applications for better insight into the important question of ice shelf stability.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Representation of sharp rifts and faults mechanics in modeling ice shelf flow dynamics: Application to Brunt/Stancomb‐Wills Ice Shelf, Antarctica

et al. 2014

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“…Field observations show that ductile fracture also occurs in ice shelf rifts, although it typically is associated with slower growth (Bassis et al, ). Linear elastic fracture mechanics is well suited to describe brittle fracture and has previously been used in the study of ice shelf rift propagation, crevasse growth, calving, and hydrofracture (Alley et al, ; Krawczynski et al, ; Krug et al, ; Larour et al, ; Nemat‐Nasser et al, ; Plate et al, ; Rist et al, ; Scambos et al, ; Smith, ; Van der Veen, ; Yu et al, ; Weertman, ).…”

Section: Introductionmentioning

confidence: 99%

Ice Shelf Rift Propagation and the Mechanics of Wave‐Induced Fracture

Lipovsky

2018

JGR Oceans

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Distant storms, tsunamis, and earthquakes generate waves on floating ice shelves. Previous studies, however, have disagreed about whether the resulting wave‐induced stresses may cause ice shelf rift propagation. Most ice shelf rifts show long periods of dormancy suggesting that they have low background stress concentrations and may therefore be susceptible to wave‐induced stresses. Here I quantify wave‐induced stresses on the Ross Ice Shelf Nascent Rift and the Amery Ice Shelf Loose Tooth T2 Rift using passive seismology. I then relate these stresses to a fracture mechanical model of rift propagation that accounts for rift cohesive strength due to refrozen melange, ice inertia, and spatial heterogeneity in fracture toughness due to the presence of high toughness suture zones. I infer wave‐induced stresses using the wave impedance tensor, a rank three tensor that relates seismically observable particle velocities to components of the stress tensor. I find that wave‐induced stresses are an order of magnitude larger on the Ross Ice Shelf as compared to the Amery Ice Shelf. In the absence of additional rift strength, my model predicts that the Nascent Rift should have experienced extensive rift propagation. The observation that no such propagation occurred during this time therefore suggests that the Nascent Rift experiences strengthening from either refrozen melange or rift tip processes zone dynamics. This study illustrates one way in which passive seismology may illuminate glacier calving physics.

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“…Field observations show that ductile fracture also occurs in ice shelf rifts, although it typically is associated with slower growth [Bassis et al, 2007]. Linear elastic fracture mechanics is well suited to describe brittle fracture and has previously been used in the study of ice shelf rift propagation, crevasse growth, calving, and hydrofracture [Weertman, 1971[Weertman, , 1973Smith, 1976;Nemat-Nasser et al, 1979;Van der Veen, 1998;Rist et al, 2002;Larour et al, 2004a;Alley et al, 2005;Krawczynski et al, 2009;Scambos et al, 2009a;Plate et al, 2012;Krug et al, 2014;Yu et al, 2017].…”

Section: Introductionmentioning

confidence: 99%

Ice shelf rift propagation and the mechanics of wave-induced fracture

Lipovsky¹

2017

Preprint

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Distant storms, tsunamis, and earthquakes generate waves on floating ice shelves. Previous studies, however, have disagreed about whether the resulting wave-induced stresses may cause ice shelf rift propagation. Most ice shelf rifts show long periods of dormancy suggesting that they have low background stress concentrations and may therefore be susceptible to wave-induced stresses. Here, I quantify wave-induced stresses on the Ross Ice Shelf Nascent Rift and the Amery Ice Shelf Loose Tooth T2 Rift using passive seismology. I then relate these stresses to a fracture mechanical model of rift propagation that accounts for rift cohesive strength due to refrozen melange, ice inertia, and spatial heterogeneity in fracture toughness due to the presence of high toughness suture zones. I infer wave-induced stresses using the wave impedance tensor, a rank three tensor that relates seismically observable particle velocities to components of the stress tensor. I find that wave-induced stresses are an order of magnitude larger on the Ross Ice Shelf as compared to the Amery Ice Shelf. In the absence of additional rift strength, my model predicts that the Nascent Rift should have experienced extensive rift propagation. The observation that no such propagation occurred during this time therefore suggests that the Nascent Rift experiences cohesive strengthening from either refrozen melange or rift tip processes zone dynamics. This study illustrates one way in which passive seismology may illuminate glacier calving physics.

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Evaluation of the criticality of cracks in ice shelves using finite element simulations

Cited by 7 publications

References 27 publications

Representation of sharp rifts and faults mechanics in modeling ice shelf flow dynamics: Application to Brunt/Stancomb‐Wills Ice Shelf, Antarctica

Representation of sharp rifts and faults mechanics in modeling ice shelf flow dynamics: Application to Brunt/Stancomb‐Wills Ice Shelf, Antarctica

Ice Shelf Rift Propagation and the Mechanics of Wave‐Induced Fracture

Ice shelf rift propagation and the mechanics of wave-induced fracture

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