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Deformation and failure of sea ice cover

Presented by: 
Jukka Tuhkuri
Tuesday 5th December 2017 - 13:30 to 14:30
INI Seminar Room 1
Sea ice cover is moved by winds and currents. This motion leads to deformation and failure; though formation of leads in tension, and through ridging and rafting in compression. This presentation concentrates on the latter process. Ridges are elongated accumulations of broken sea ice. Rafting is another form of deformed ice. During rafting, one ice sheet overrides another ice sheet. Several models of ridging and rafting have been proposed: energy based models, models concentrating on the kinematics of the processes, and numerical models. Also laboratory experiments have been conducted to study ridging and rafting. In essence, all ridging and rafting initiates when two ice sheets are pushed together. In rafting, one ice sheet slides under another ice sheet, and we get two (or more) overlapped ice sheets. In ridging, ice blocks sequentially break of the ice sheets and form a ridge. Our experimental and numerical work suggests that all ridging initiates as rafting. Also, as the ice-ice friction coefficient is larger than zero, a rafting process will eventually turn into the formation of a pile of broken ice blocks, a ridge. Therefore, rafting and ridging should not be considered as two totally different deformation processes, but rather different stages of one process.
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University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons