ASA 126th Meeting Denver 1993 October 4-8

1pAO1. Fracture of sea ice.

Ira Dyer

Dept. of Ocean Eng., MIT, 77 Massachusetts Ave., Cambridge, MA 02139

The major cause of ambient noise in the Arctic Ocean is radiation from the fracture of sea ice in response to environmental forcing. Extant noise data on fracture in pack ice in the central Arctic and in free-drifting ice at its margins, including measures such as spectral density, temporal evolution, and individual ice fracture transients and their statistics are reviewed. Physical mechanisms responsible for ice fracture are of fundamental interest, and therefore the fracture mechanics of sea ice, which leads to a picture of ice failure not unlike that of failure in the Earth's crust via earthquakes, is also discussed. As in earthquakes, ice fracturing is a process of many small fault plane motions which can result in a major ice crack. Prospects for use of noise measurements to understand ice processes immediately come to mind, as well as their use intrinsically to describe acoustic properties of the Arctic Ocean.