Researchers from the University of Chicago have reordered hundreds of thousands of tiny “ice quakes” tracking the melting process in the McMurdo Ice Shelf in the Antarctic. As the university’s media service reports, they placed seismometers in the so-called “dry” and “slushy” stations, named after the aspects of the melting process there to find out why giant ice shelves collapse unexpectedly before they begin to float.
The experiment took 60 days. The wetter locations, with pools of melted water refreezing, were proved to be seismically active at night. The seismometers were said to catch tiny vibrations.
“In these ponds, there’s often a layer of ice on top of melted water below, like you see with a lake that’s only frozen on top. As the temperature cools at night, the ice on the top contracts and the water below expands as it undergoes freezing. This warps the top lid until it finally breaks with a snap”, Douglas MacAyeal, a professor of geophysical sciences who co-authored the study, said.
The academic says that while some cracks freeze back together, others keep growing. At the same time, seismic activities in dry areas might be explained by human activities. The researchers concluded that "thermally regulated seismicity may exist on all ice shelves that undergo surface melting and freezing, especially those that have lost their protective, insulating firn layer", although this remains a hypothesis.
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This method of tracking could contribute to studying the physics and processes of melting ice shelves, as glaciologists are investigating how, where, and why ice in Antarctica is melting, according to the media.
“In these areas, we would record tens, hundreds, up to thousands of these per night. It’s possible that seismometers may be a practical way for us to remotely monitor glacier melting”, MacAyeal said.
