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Scientists have discovered their first icequake, if you will — a movement of a huge stream of ice in Antarctica that creates seismic waves, just like an earthquake, and can be felt hundreds of miles away.

Starting in 2001, Douglas Wiens of Washington University in St. Louis deployed seismographs around Antarctica, which detected seismic signals between that year and 2003.

"At first we didn't know where the waves were coming from, but eventually we were able to narrow down the source to the ice stream," Wiens said.

These ice-driven seismic waves had the force of a magnitude 7 earthquake, he said. That's equivalent to the strength of the 2005 Fukuoka earthquake, which killed only one, but displaced more than 3,000 people.

Glacial earthquakes

Prior to Wiens' discovery, detailed in the June 5 online issue of the journal Nature, scientists were unaware that ice streams radiated seismic waves (though they had detected them from glaciers, mainly near Greenland).

Ice streams are pieces of a bigger ice sheet that can move faster than the surrounding ice, periodically sliding over the underlying bedrock and eventually working their way to the coastline, where the ice can calve off to create icebergs...