Propagation of Elastic Waves in Ice. Part II

Flexural waves. A seismograph, used to study propagation of explosion-generated waves in a sheet of ice on a lake, revealed the existence of flexural waves. These waves showed marked dispersion, the group velocity being represented approximately by the empirical formula U=221(en)½, where e is the thickness of the ice in feet and n is the frequency. A theoretical formula is developed by which the velocity of these waves may be calculated from the elastic constants of ice and water. Transverse waves. By a suitable orientation of the seismograph it was possible to detect transverse waves, polarized horizontally, in the sheet of ice. The velocity of transverse waves was found to be 6057 ft./sec. which checks within about three percent with the value of velocity calculated from the elastic constants of ice as reported in Part I.