Dispersion of Sound Waves in Ice Sheets

I discovered this incredible recording of ice sheets cracking.
It was recorded with underwater microphones. The article describes how the sound waves are propogated.

Link: http://silentlistening.wordpress.com/2008/05/09/dispersion-of-sound-waves-in-ice-sheets/

Here's an updated post: http://silentlistening.wordpress.com/2010/01/17/ice-recordings-updated/