Within glacial ice sheets, there are streams of ice, sometimes called ice rivers, that move much faster than the surrounding ice. If you’re having trouble imagining how ice moves inside ice, Elizabeth Thomas, a paleoclimatologist at the University at Buffalo, suggests an analogy to help visualize these icebound rivers.
Since the Gulf Stream carries warm water from the tropical Atlantic Ocean up the coast of the Carolinas and then across to Europe, she explains, “the Gulf Stream is essentially a river of water that's flowing faster than the ocean around it.”
The same thing happens in ice sheets. Most of the ice moves very slowly, but in some places, the ice moves much more swiftly than the surrounding ice, and those faster-moving areas are ice streams. And within these streams, researchers have discovered ice quakes.