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Antarctic ice shelf 'sings' as winds whip across its surface



Study co-author Rick Aster during a station trip on the Ice Shelf, holding a broadband seismometer. These sensitive sensors were buried at depths of two meters (6 feet) to record micro-scale seismic motions of the ice shelf in three dimensions over the course of two years. Credit: Rick Aster.
    

Antarctica's Ross Ice Shelf causes the massive ice slab's surface to vibrate, producing a near-constant set of seismic "tones" that could potentially change to the ice shelf from afar, according to new research.
                                

The Ross Ice Shelf is Antarctica's largest ice shelf, a Texas-sized plate of glacial ice from the icy continent's interior that floats atop the Southern Ocean. The ice shelves and ice sheets on Antarctica's mainland,

When ice shelves collapse, which can raise sea levels. Ice shelves all over Antarctica have been thundering, and in some cases breaking up or retreating, due to rising ocean and air temperatures. Prior Observations have shown that when the Larsen B ice shelf on the Antarctic Peninsula abruptly collapsed in 2002.

To better understand the physical properties of the Ross Ice Shelf, researchers buried 34 extremely sensitive seismic sensors under its snowy surface. The sensors are used to shed the ice shelf and vibrate and study for over two years, from late 201

4 to early 2017.

Ice shelves are covered in deep snow, often several meters deep, that are topped with massive snow dunes, like sand dunes in a desert.

When the researchers start analyzing seismic data on the Ross Ice Shelf, they say something odd: Its for coat what is almost constantly vibrating.

When they look at the data, they discover the snow around the massive snow dunes. Listen to the ice sheet's "song" here.


They thus noticed the pitch of this seismic changed when the snow layer's surface changed.

"It's kind of like you're. It's kind of kind of like you're blowing a flute, constantly, on the ice shelves, "said Julien Chaput, a geophysicist and mathematician at Colorado State University in Fort Collins and lead author of the new study published today in Geophysical Research Letters a journal of the American Geophysical Union.

Just like a student can change his or her voice by altering the sound of his or her voice dune-like topography, according to Chaput.

"Either you change the velocity of the snow by heating or cooling it, or you change it on the flute, by adding or destroying it," he said.

The shells are in the same state as the human eye real-time. Douglas MacAyeal, a glaciologist at the University of Chicago, said: "It's not as good as it is." the findings also published today in Geophysical Research Letters .

Changes to the ice shelf's seismic hum could indicate whether or not ponds or cracks in the ice are forming the ice shelf is susceptible to breaking up

"The response of the ice shelf that we can track is extremely sensitive about it," Chaput said. "Basically, what we have on our hands is a tool to monitor the environment, really."
                                                                


Explore further:
                                        Retracing Antarctica's glacial past
                                    

More information:
                                        Chaput et al., Near-Surface Environmentally Forced Changes in the Ross Ice Shelf Observed With Ambient Seismic Noise, Geophysical Research Letters (2018). DOI: 10.1029 / 2018GL079665
                                        

Journal reference:
                                                                                                            Geophysical Research Letters
                                                        
                                                        
                                                                                                    

Provided by:
                                                                                                            American Geophysical Union
                                                        

                                                        
                                                                                                    


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