Published: Sat, October 20, 2018
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Scientists capture eerie seismic howl of Antarctic ice shelf - 19-Oct

Scientists capture eerie seismic howl of Antarctic ice shelf - 19-Oct

This image provided by NASA shows the largest remaining piece of the slowly disintegrating B17B iceberg, which broke off Antarcticas Ross Ice Shelf.

The researchers gathered data over the course of two years and found the Ross Ice Shelf "nearly continuously sings at frequencies of five cycles or more", according to Chaput's research letter.

"We discovered that the shelf almost continuously sings at frequencies of five or more cycles per second, excited by local and regional winds blowing across its snow dune‐like topography", in a press release.

The sound was measured by a team of scientists who placed seismic sensors under the snow on the Ross Ice Shelf, in order to monitor the structure and movement of the ice.

Not only were whipping winds causing the ice sheet's snow to rumble, but the pitch of this seismic hum also changed depending on the slushy surface conditions.

"It's kind of like you're blowing a flute, constantly, on the ice shelf", Julien Chaput, a geophysicist at Colorado State University and lead author of the study, said in a statement.

"Basically, what we have on our hands is a tool to monitor the environment, really", he added.

Ice shelves are covered in a thin blanket of snow, typically several meters deep, that insulates the ice below from warming and melting like a fur coat. What they heard however, the creeping "singing" of the ice shelf, is not at all what the anticipated they would find.

The researchers noticed that the height of seismic hum changes when under the influence of weather conditions of snow dunes "rebuilt" or when the temperature abruptly rises or falls.

"The response of the ice shelf tells us that we can track extremely sensitive details about it", Chaput said. The firn had been altered permanently, and the ice shelf song was changed permanently as well. Shifts in the ice's vibrational frequencies could reveal the early formation of cracks or melt ponds - signs of structural instability. "Deploying a single seismometer on an ice shelf could provide the means of observing very subtle environmental forcing, on time scales as short as minutes, and would provide a means to directly understand the sequence of physical changes that happen in the near surface as a melting event strikes".

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