ASA 124th Meeting New Orleans 1992 October

2pUW7. Additional data on low-frequency elastic wave propagation in ice.

Peter J. Stein

Atlantic Appl. Res. Corp., 4 ``A'' St., Burlington, MA 01803

Current ONR initiatives in ice mechanics research are looking toward using wave propagation in Arctic pack ice as a means to probe the ice mechanical properties. The most robust modes of wave propagation are the low-frequency (<100 Hz) flexural, longitudinal, and horizontally polarized shear waves. Here use is made of multi-sensor triaxial geophone data from the ICEX-1-90 experiment and the March 1992 Allen Bay ice mechanics-acoustics experiment to further analyze these waves under ideal first-year ice conditions. Data will be presented on wave speeds (2750 m/s for longitudinal and 1650 m/s for shear), attenuations, and scattering. Inverting this data to obtain ice mechanical properties such as the moduli, Poisson's ratio, density, and thickness, will also be looked at. Discussion will address the impact of the nonuniform vertical structure of the ice and the accuracy to which the mechanical properties can be uniquely specified. [Work supported by ONR Arctic Sciences Program.]