Subglacial hydrology and the formation of ice streams

Kyrke-Smith, Teresa M.; Katz, Richard F.; Fowler, A. C.

doi:10.1098/rspa.2013.0494

Cited by 62 publications

(85 citation statements)

References 83 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The dependence of Γ on ice flow may have a dynamical effect on a large scale [37], but in fact Γ is negligible on the small length scale of concern here. We scale these equations using values in (2.11), and in addition…”

Section: (I) Non-dimensionalizationmentioning

confidence: 99%

An instability theory for the formation of ribbed moraine, drumlins and mega-scale glacial lineations

Fowler

Chapwanya

2014

Proc. R. Soc. A.

View full text Add to dashboard Cite

We present a theory for the coupled flow of ice, subglacial water and subglacial sediment, which is designed to represent the processes which occur at the bed of an ice sheet. The ice is assumed to flow as a Newtonian viscous fluid, the water can flow between the till and the ice as a thin film, which may thicken to form streams or cavities, and the till is assumed to be transported, either through shearing by the ice, squeezing by pressure gradients in the till, or by fluvial sediment transport processes in streams or cavities. In previous studies, it was shown that the dependence of ice sliding velocity on effective pressure provided a mechanism for the generation of bedforms resembling ribbed moraine, while the dependence of fluvial sediment transport on water film depth provides a mechanism for the generation of bedforms resembling mega-scale glacial lineations. Here, we combine these two processes in a single model, and show that, depending largely on the granulometry of the till, instability can occur in a range of types which range from ribbed moraine through three-dimensional drumlins to mega-scale glacial lineations.

show abstract

Section: (I) Non-dimensionalizationmentioning

confidence: 99%

An instability theory for the formation of ribbed moraine, drumlins and mega-scale glacial lineations

Fowler

Chapwanya

2014

Proc. R. Soc. A.

View full text Add to dashboard Cite

show abstract

“…[78,214]). Models that do treat hydrology have been developed for the Siple Coast ice streams, which are underlain by thick saturated sediments and lack strong topographic controls.…”

Section: Models Of Antarctic Basal Hydrologymentioning

confidence: 99%

“…Sheet-like drainage under ice streams has been adopted by Kyrke-Smith et al [78] in a twodimensional plan-view model coupled to ice flow that exhibits spontaneous development of ice streams. A Weertman-like sheet overlies a saturated low-permeability till, and becomes unstable when it decouples from its supporting clasts [114] (figure 18a).…”

Section: Models Of Antarctic Basal Hydrologymentioning

confidence: 99%

Modelling water flow under glaciers and ice sheets

2015

View full text Add to dashboard Cite

Recent observations of dynamic water systems beneath the Greenland and Antarctic ice sheets have sparked renewed interest in modelling subglacial drainage. The foundations of today's models were laid decades ago, inspired by measurements from mountain glaciers, discovery of the modern ice streams and the study of landscapes evacuated by former ice sheets. Models have progressed from strict adherence to the principles of groundwater flow, to the incorporation of flow 'elements' specific to the subglacial environment, to sophisticated twodimensional representations of interacting distributed and channelized drainage. Although presently in a state of rapid development, subglacial drainage models, when coupled to models of ice flow, are now able to reproduce many of the canonical phenomena that characterize this coupled system. Model calibration remains generally out of reach, whereas widespread application of these models to large problems and real geometries awaits the next level of development.

show abstract

“…Since most ice flux in Antarctica occurs through ice streams (Whillans et al, 1987;Rignot et al, 2011), understanding the conditions that cause ice-stream stagnation is of basic importance in constraining the continent's contribution to future sea level rise. Although recent progress has been made in describing the relationship between basal conditions and ice stream motion (Bougamont et al, 2011(Bougamont et al, , 2015Robel et al, 2013;Kyrke-Smith et al, 2014, direct observation of the temporal variation in subglacial conditions during ice-stream stagnation has remained elusive.…”

Section: Introductionmentioning

confidence: 99%

Tremor during ice-stream stick slip

Lipovsky¹,

Dunham²

2016

The Cryosphere

View full text Add to dashboard Cite

Abstract. During the 200 km-scale stick slip of the Whillans Ice Plain (WIP), West Antarctica, seismic tremor episodes occur at the ice-bed interface. We interpret these tremor episodes as swarms of small repeating earthquakes. The earthquakes are evenly spaced in time, and this even spacing gives rise to spectral peaks at integer multiples of the recurrence frequency ∼10-20 Hz. We conduct numerical simulations of the tremor episodes that include the balance of forces acting on the fault, the evolution of rate-and statedependent fault friction, and wave propagation from the fault patch to a seismometer located on the ice. The ice slides as an elastic block loaded by the push of the upstream ice, and so the simulated basal fault patch experiences a loading velocity equal to the velocity observed by GPS receivers on the surface of the WIP. By matching synthetic seismograms to observed seismograms, we infer fault patch area ∼10 m 2 , bed shear modulus ∼20 MPa, effective pressure ∼10 kPa, and frictional state evolution distance ∼1 µm. Large-scale slip events often occur twice daily, although skipped events have been increasing in frequency over the last decade. The amplitude of tremor (recorded by seismometers on the ice surface) is greater during the double wait time events that follow skipped events. The physical mechanism responsible for these elevated amplitudes may provide a window into nearfuture subglacial conditions and the processes that occur during ice-stream stagnation.

show abstract

Subglacial hydrology and the formation of ice streams

Cited by 62 publications

References 83 publications

An instability theory for the formation of ribbed moraine, drumlins and mega-scale glacial lineations

An instability theory for the formation of ribbed moraine, drumlins and mega-scale glacial lineations

Modelling water flow under glaciers and ice sheets

Tremor during ice-stream stick slip

Contact Info

Product

Resources

About