That may not sound like much, but ice shelves can be well over 1,000 feet thick, and are essentially are immune to the effects of ocean waves.
Infragravity waves are another animal, though. They form when waves from a large ocean-going storm crash into shallow waters. Energy from the waves is warped, elongated and cast back out to sea and can echo for thousands of miles.
"Regular sea swell chips off little icebergs from the edges," Peter Bromirski of the Scripps Institute of Oceanography said. "Infragravity waves could be affecting a much greater part of the ice shelf."
Bromirski led a team of researchers who examined seismic rumblings on Antarctica's biggest shelf, the France-sized Ross Ice Shelf during the southern summer of 2005-2006.
Ross is stable, but the team found that winter storms in the north Pacific Ocean sent infragravity waves all the way to Antarctica. The ice rattled noticeably as each wave rolled underneath.
"The key thing is we are not at a position yet to say, 'Oh my God, infragravity waves are the proximal cause of ice shelf break up,'" team member Douglas MacAyeal of the University of Chicago cautioned.