THE CURIOUS CASE OF THE 'SINGING' ANTARCTIC ICE SHELF.

Winds blowing across dunes on Antarctica's Ross Ice Shelf cause the massive ice slab's surface to vibrate, producing a near-constant set of seismic 'tones' which could be used to monitor changes in the ice from afar, according to a study. The Ross Ice Shelf is Antarctica's largest ice shelf, a Texas-sized plate of glacial ice fed from the icy continent's interior that floats atop the Southern Ocean, said researchers at Colorado State University in the US. The ice shelf buttresses adjacent ice sheets on Antarctica's mainland, impeding ice flow from land into water, like a cork in a bottle, according to the study published in the journal 'Geophysical Research Letters'.
When the researchers started analysing seismic data on the Ross Ice Shelf, they notice something odd: Its fur coat was constantly vibrating. "It's kind of like you are blowing a flute, constantly, on the ice shelf", said Julien Chaput, a geophysicist at Colorado State University. To better understand the physical properties of the Ross Ice Shelf, researchers buried 34 extremely sensitive seismic sensors under its snowy surface. The sensors allowed the researchers to monitor the ice shelf's vibrations and study its movements for over two years, from late 2014 to early 2017. Ice shelves are covered in thick blankets of snow, often several metres deep, that are topped with massive snow dunes. This snow layer acts like a fur coat for the underlying ice, insulating the ice below from heating and melting when temperatures rise.
Researchers discovered winds whipping across the massive snow dunes caused the ice sheet's snow covering to rumble, like the pounding of a colossal drum. They also noticed the pitch of this seismic hum changed when weather conditions altered the snow layer's surface. Researchers found the ice vibrated at different frequencies when strong storms re-arranged the snow dunes or when the air temperatures at the surface went up or down.
[Based on a news item published in The Times of India dated 18th October, 2018 (Thursday)]  
-Challapalli Srinivas Chakravarthy-
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