Structural provinces of the Ross Ice Shelf, Antarctica

Ledoux, C. M.; Hulbe, Christina L.; Forbes, Martin; Scambos, Ted; Alley, Karen E.

doi:10.1017/aog.2017.24

Cited by 24 publications

(37 citation statements)

References 42 publications

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“…I have chosen a value K c = 400 kPa

\sqrt{normalm}

to represent the fracture toughness of ice shelf suture zones. This choice is based on the best available laboratory data (Rist et al, ), and was chosen to be at the high end of laboratory data to reflect the fact that suture zones appear to be more resistant to rift propagation than the surrounding ice shelf (Holland et al, ; Jansen et al, ; LeDoux et al, ; McGrath et al, ). I also invoke the laboratory measurements to support the claim that fracture toughness variations cannot entirely be responsible for the observed response of the Nascent Iceberg Rift to wave‐induced stresses.…”

Section: Discussionmentioning

confidence: 99%

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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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“…I have chosen a value K c = 400 kPa

\sqrt{normalm}

Section: Discussionmentioning

confidence: 99%

“…I note that this description accounts for spatial variability in fracture toughness due, for example, to the presence of high toughness suture zones with accreted basal marine ice (Holland et al, ; Jansen et al, ; LeDoux et al, ; McGrath et al, ).…”

Section: Fracture Mechanicsmentioning

confidence: 99%

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

Lipovsky

2018

JGR Oceans

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“…2). There is no indication of pinning points in this region, which implies this region of compression arises from the redirection of flow as the glacier merges with the Ross Ice Shelf (LeDoux and others, 2017).…”

Section: Resultsmentioning

confidence: 99%

Tidal and spatial variability of flow speed and seismicity near the grounding zone of Beardmore Glacier, Antarctica

et al. 2019

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GPS measurements of tidal modulation of ice flow and seismicity within the grounding zone of Beardmore Glacier show that tidally induced fluctuations of horizontal flow are largest near the grounding line and decrease downstream. Seismic activity is continuous, but peaks occur on falling and rising tides. Beamforming methods reveal that most seismic events originate from two distinct locations, one on the grid-north side of the grounding zone, and one on the grid-south side. The broad pattern of deformation generated as Beardmore Glacier merges with the Ross Ice Shelf results in net extension along the grid-north side of the grounding zone and net compression along the grid-south side. During falling tides, seismic activity peaks on both sides because of increased vertical flexure across the grounding line. During rising tides, seismic activity in the region of extension on the grid-north side is relatively low because the tidal influence on both horizontal strain rate and vertical flexure is small. On the grid-south side during rising tides, however, tidally induced horizontal strain rates promote increased seismicity in regions of long-term compressional flow paths. Our study highlights how concurrent geodetic and seismic measurements provide insight into grounding-zone mechanics and their influence on ice-shelf buttressing.

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“…I note that this description accounts for spatial variability in fracture toughness due, for example, to the presence of high toughness suture zones with accreted basal marine ice [Holland et al, 2009;McGrath et al, 2012;Jansen et al, 2013;LeDoux et al, 2017]. [Scambos et al, 2007].…”

Section: Inertial Effects During Rift Tip Propagationmentioning

confidence: 99%

“…I have chosen a value K c = 400 kPa √ m to represent the fracture toughness of ice shelf suture zones. This choice is based on the best available laboratory data [Rist et al, 2002], and was chosen to be at the high end of laboratory data to reflect the fact that suture zones appear to be more resistant to rift propagation than the surrounding ice shelf [Holland et al, 2009;McGrath et al, 2012;Jansen et al, 2013;LeDoux et al, 2017]. I also invoke the laboratory measurements to support the claim that fracture toughness variations cannot entirely be responsible for the observed response of the Nascent Iceberg Rift to wave-induced stresses.…”

Section: The Fracture Toughness Of Ice Shelf Suture Zonesmentioning

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.

show abstract

Structural provinces of the Ross Ice Shelf, Antarctica

Cited by 24 publications

References 42 publications

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

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

Tidal and spatial variability of flow speed and seismicity near the grounding zone of Beardmore Glacier, Antarctica

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

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