Scientists, for the first time, have recorded thousands of tiny ice quakes that are sporadically shaking the Greenland Ice Sheet. The study noted that these weak quakes are taking place deep within the ice streams triggering one another and propagating over distances of hundreds of metres. 

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Ice quakes, similar to earthquakes, are seismic events that can happen in ice when it fractures and two slabs press against each other. Scientists have said that these ice quakes might provide deeper insights into the pattern in which the island's frozen rivers move downstream towards the sea. 

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The study said that this previously unknown phenomenon will change the way experts document ice melt and rising sea levels, which is important to understanding changing climate and global heating. 

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Greenland's ice sheet is the second-largest body of ice globally, which covers around 80 per cent of the island's surface. Experts have estimated it to be approximately 1.67 kilometres thick on average. It reaches up to 3 kilometres at its thickest point. This massive ice sheet has been around for at least 18 million years. 

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To conduct the study, researchers lowered a fibre-optic cable into a 1.7-mile-deep (2.7 kilometres) borehole in the Northeast Greenland Ice Stream, which is Greenland's largest frozen river. 

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The study, titled, "Hidden cascades of seismic ice stream deformation", was published in the journal Science, and was conducted by a team of researchers led by ETH professor Andreas Fichtner. 

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Why were the quakes not discovered before? 

In a statement, the researchers said that ice quakes in Greenland have gone undetected until now because they are blocked from reaching the surface by a layer of volcanic particles buried 2,950 feet (900 meters) beneath the ice. 

These volcanic particles originated from a massive eruption of Mount Mazama in what is now Oregon (USA) some 7,700 years ago. "We were astonished by this previously unknown relationship between the dynamics of an ice stream and volcanic eruptions," Fichtner said as quoted in the statement. 

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The study's co-author Olaf Eisen, a professor of glaciology at the Alfred Wegener Institute for Polar and Marine Research in Germany, said in the statement: "The fact that we've now discovered these ice quakes is a key step towards gaining a better understanding of the deformation of ice streams on small scales." 

"The assumption that ice streams only flow like viscous honey is no longer tenable. They also move with a constant stick-slip motion," Fichtner noted. 

(With inputs from agencies)