Scientists have recorded thousands of previously undetected ice quakes sporadically shaking the Greenland Ice Sheet. The discovery, made using a fiber-optic cable lowered into a 1.7-mile-deep borehole in the Northeast Greenland Ice Stream, reveals that these weak quakes occur deep within the ice streams, triggering one another and propagating over hundreds of meters.
These seismic events, similar to earthquakes, happen when ice fractures and slabs press against each other. Researchers believe that studying these ice quakes will provide deeper insights into how Greenland's frozen rivers move downstream toward the sea. The team, led by ETH professor Andreas Fichtner, published their findings in the journal Science.
The study indicates that this previously unknown phenomenon will change how experts document ice melt and rising sea levels, crucial for understanding climate change and global heating. Olaf Eisen, a professor of glaciology at the Alfred Wegener Institute for Polar and Marine Research in Germany, stated that this discovery is a key step toward a better understanding of ice stream deformation on small scales.
The ice quakes had gone undetected because a layer of volcanic particles, originating from the eruption of Mount Mazama in Oregon (USA) about 7,700 years ago, blocks them from reaching the surface. Fichtner noted that the assumption that ice streams only flow like viscous honey is no longer tenable, as they also move with a constant stick-slip motion.