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Antarctica is no stranger to strange sounds, trapped old air bubbles bursting with ice patches disintegrating. Now we can add another weird track to the work of icy masterpieces.
Scientists monitoring Ross ice floes in West Antarctica have captured this acoustic anomaly. With the help of a series of ultra-sensitive seismic sensors, they created a soundscape perfectly suited to a haunted Halloween home or to the soundtrack of a B-movie series of years 1950 on the extraterrestrials arriving on Earth. But beyond being scary, the sounds reveal how processes ranging from warming winds to changing Antarctic ice.
Julien Chaput, an expert in ambient noise monitoring at Colorado State University and a new professor at the University of Texas, El Paso, told Earther that these records were a "happy accident." In 2014, researchers deployed seismic material on the Ross ice floe, the largest ice floe in Antarctica, to study the crust and mantle below. Chaput jumped on board hoping to control the seasonal changes in the pack ice mass, "and instead discovered strange spectral anomalies beyond easy explanation, suggesting seismic waves trapped at high frequencies in the last two meters of snow."
Essentially, surface disturbances are trapped in the form of seismic waves propagating on the pack ice. The team documented these wild waves in an article in Geophysical Research Letters published Tuesday. They also released some of the sounds they had captured over the course of more than two years of continuous recording (speeded up below for your convenience).
The last two meters of snow and ice are called "dwarfs" and are very vulnerable to what happens above the surface, changes in wind and changes in temperature. And with sensitive seismic material buried beneath the surface, Chaput has been able to document much more than just seasonal movements.
The frequency of the melody has changed after the passage of storms, which in itself is interesting. But what really caught the eye is a hot January 2016 when temperatures creaked below freezing. The pitch of the melody dropped during this trip, indicating that snow and ice melted, slowing the spread of seismic waves through the ground. More importantly, the fall of height is not reversed once temperatures are restored, indicating permanent or semi-permanent changes in the pine layer.
"Nest melt is widely considered to be one of the most important factors in the destabilization of pack ice, which in turn accelerates the flow of ice into the ocean from the ice sheets," Chaput said.
The Ross ice floe is located in the West of Antarctica. Some parts may face irreversible melting due to the shape of the bedrock beneath the ice that allows warm ocean currents to undermine the floating ice shelves. The melting of this unstable region could raise sea level by about 10 feet. The warming of the surface could add another layer of stress that scientists will have to watch closely.
Chaput emphasized that seismic monitoring is a way to keep an eye on one of the most remote places in the world and help researchers answer questions about the ability to withstand rising temperatures. And of course, this type of surveillance could provide more musical content for the horror movie soundtrack, though, if we're real, what's happening in Antarctica is already scary enough.
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