Antarctica is singing. Scientists found that one of the world's biggest slabs of ice is producing an almost continuous series of tones.
The phenomenon was observed by accident at the Ross Ice Shelf. Scientists who were monitoring the vibrations of the largest ice shelf within the continent were "stunned" to discover the low hum caused by the wind blowing over its snow dunes.
A study that discusses the seismic noise created by the Ross Ice Shelf was published in the journal Geophysical Research Letters of the American Geophysical Union.
The Singing Ice Shelf
Unfortunately, the gentle song of the ice shelf is too low for the human ears to hear — the sound registers at about >5 Hz frequency. To "listen" to the seismic tones of the Ross Ice Shelf, scientists buried sensitive sensors beneath the ice surface. A sped-up recording of the hum was released by the American Geophysical Union on its social media pages (watch below).
"It's kind of like you're blowing a flute, constantly, on the ice shelf," described geophysicist Julien Chaput, the lead author of the study.
The low hum of the Ross Ice Shelf is produced when the wind blows across the snow dunes, causing the surface to vibrate and produce a seismic tone only sensitive machines can detect. Scientists were at the site to study the low-frequency vibrations caused by earthquakes and ocean waves. However, upon closer look, they discovered that the surface of the ice sheet is constantly vibrating.
They also found that the hum of the ice shelf changed according to weather conditions. When there is a strong storm blowing wind over the surface of the ice shelf and rearranging the snow layer over it, the ice vibrates at different frequencies. The air temperature also affects how fast the seismic waves travel through the snow on the surface. The scientists compare the process to a musician changing the pitch of a note on a flute by altering the speed of air flow or picking which hole the air exits.
"Either you change the velocity of the snow by heating or cooling it, or you change where you blow on the flute, by adding or destroying dunes," explained Chaput. "And that's essentially the two forcing effects we can observe."
Diagnosing The Ross Ice Shelf
The researchers hope that the changes to the ice shelf's seismic hum could reveal new details about the ice shelf, specifically if it is in danger of breaking apart.
The Ross Ice Shelf is the biggest slab of ice in Antarctica. It measures at about 487,000 square-kilometers or about the size of Texas and France. It also plays an important role in stabilizing the ice sheet in the continent and acts as a "cork" that prevent inland glaciers from melting into the ocean.
Because of global warming, ice sheets in Antarctica are growing thinner. Some have retreated or even collapsed due to the rising ocean and warming temperature.
