In a first, researchers have recorded countless "ice quakes" that sporadically shake the Greenland Ice Sheet. These quakes may explain the jerky way that the island's frozen rivers move downstream toward the sea, the scientists say.
Researchers detected these quakes by lowering a fiber-optic cable into a 1.7-mile-deep (2.7 kilometers) borehole in the Northeast Greenland Ice Stream — Greenland's largest frozen river that serves as the main artery through which ice is discharged from the ice sheet's interior into the North Atlantic Ocean.
