Creep Deformation of Ice

Knowledge of the creep properties of ice often is needed in field and theoretical studies of the flow and deformation of glaciers, ice shelves, and ice sheets. Recently many of the icy moons in the solar system have become much better known as a result of the successful deep-space probe missions. An understanding of the physical processes that take place within them requires information about the plastic deformation behavior of ice. Unlike ice within glaciers and ice sheets, the crystal structure of ice deep within an icy satellite may be one of the high-pressure polymorphs rather than that of the more familiar hexagonal ice Ih. At the present time, there exists a great deal of creep data on ordinary ice Ih but very little on other forms of ice. The aim of this article is to present our basic knowledge on the creep properties of ice. This includes information derived from laboratory experiments as well as gleaned from field measurements made on glaciers, ice sheets, and ice shelves. No attempt is made here to review in a complete manner all the literature on this subject. However, new results from recent papers on ice creep that are not covered in earlier and more complete reviews are included. The reader is referred to the reviews of Hooke (1981; called review H hereafter), Paterson (1977; called review P), Glen (1974, 1975; called review G), and Weertman (1973; called review W) for a more complete coverage of the earlier literature. Review H compares experi­ mental results on ice creep with field measurements on glaciers and other large bodies of ice. Review P summarizes closure data on boreholes in the Antarctic and Greenland ice sheets and Canadian ice caps. Review G covers most aspects of the mechanics and physics of ice. A tutorial-type review on polycrystalline ice has been given by Mellor (1980; called review