“It’s something like 300 to 400 gigatons of ice per year”. “That’s kind of the dimensions of an ice dice you’d have should you crammed up Central Park in New York City to the highest of the Empire State Building”, she added.
“You see an enormous chunk of ice gradually start to tilt over, and it just lifts up all the water on top of it right up toward you as the iceberg continues to fall over”. “The mass loss of ice from Greenland is quite large”, she continued. “And then very quickly, everything is still again”. During this period, they have recorded 10 glacial earthquakes, in which some of the phenomenon reached to about 5.0 in magnitude in the Richter Scale.
“They are different from regular earthquakes”.
They also placed two cameras in front of the calving border, which took pictures on an hourly basis. Instead of taking just seconds and generating rapid shaking, like an natural disaster from the San Andreas Fault, a glacial natural disaster can last a minute.
Scientists from an global team suspect that the calving events and the glacial earthquakes are interlinked even though there was not enough data to support the theory.
The event is named glacial quake as it causes phenomenal earth movements that are picked up by seismic instruments.
Scientist Tavi Murray and colleagues at Columbia University, Swansea University, Newcastle University, and others wanted to find out what was happening when the earth shakes like this, according to a release. “We’re really trying to understand, how does that seismic signal get created, when this ice detaches from the ice sheet”, she explains.
Back in the lab, the researchers ran simulations in a cylindrical tank mimicking the fjords, which are thin fingers of seawater that extend into land (and where the water meets the Helheim Glacier wall). Their cameras, GPS sensors and the worldwide seismographic community confirmed how the glaciers fell away from the icebergs and briefly reversed it course and consequently resulted to glacial earthquakes. In Greenland, scientists who were engaged in tracking the glacial earthquakes managed to crack the mystery behind the dynamics of what is known as calving icebergs.
In a report published by the journal Science, they say a giant iceberg falling over generates a big enough force that it actually pushes back on the glacier, making it move backward and downward for several minutes.
Nettles stated, “Imagine that you possibly can go and simply push on the entrance of the glacier together with your thumb, actually onerous, so arduous that you possibly can reverse the path that the entrance of the glacier is shifting. And that backward after which ahead movement is definitely recorded within the GPS knowledge from the entrance of the glacier”.
“We found that we were actually having to sit there very carefully, looking at it and going, ‘Do you see anything moving?”
Calving icebergs or glacier ice is the cause of glacial earthquakes that are triggered by a massive shard cracking like gunshot and leads to disintegration of the frozen wall.
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