Stress state and mechanics of glacier shelvescollapse

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Abstract

The stress state of ice shelves using numerical modeling is studied. An ice shelf is modeled by an elastic plate floating on water and attached to the ice cover at a grounding point. An analytical solution for the elastic bending of the plate is obtained and it is shown that the maximum tensile stresses on the lower surface of the glacier near the grounding point can reach values of 5×107 Pa, significantly exceeding the limiting strength values of the glacier. The fragmentation of a glacier that occurs when a glacier moves under conditions of constrained compression has been studied. It is shown that deformations of the ice plate are accompanied by the formation of zones of localization of inelastic deformations (ice ridges). A comparison was made of the calculated relief of the plate surface after localization of deformations with the pattern of hummocking of the Larsen Glacier, visible on satellite images.

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About the authors

I. A. Garagash

Schmidt Institute of Physics of the Earth, Russian Academy of Sciences

Email: aabaranov@gmail.com
Russian Federation, Moscow

L. I. Lobkovsky

P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences

Email: aabaranov@gmail.com

Academician of the RAS

Russian Federation, Moscow

А. А. Baranov

Schmidt Institute of Physics of the Earth, Russian Academy of Sciences

Author for correspondence.
Email: aabaranov@gmail.com
Russian Federation, Moscow

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2. Fig. 1. Sketch of a cross-section of an Antarctic glacier near the coast.

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3. Fig. 2. Ice height above sea level (a) and distribution of maximum tensile stresses at the lower boundary of the glacier (b). Curves 1 and 2 correspond to thickness values h = 200 m and h = 600 m, respectively.

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4. Fig. 3. Additional displacements (a) and maximum tensile stress at the lower boundary of the glacier (b), calculated for a maximum tidal height of 2 m. Curves 1 and 2 correspond to thickness values h = 200 m and h = 600 m, respectively.

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5. Fig. 4. The system of cracks of the Larsen Ice Shelf (a) and the calculated area of the ice field (b).

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6. Fig. 5. Development of zones of localization of shear deformations in an ice field, associated with an increase in compressive stresses.

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7. Fig. 6. Regularities of vertical displacements in zones of localization of shear deformations, increasing from several centimeters (a) to tens of meters (b) as compressive stresses increase.

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