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New Study Suggests Link Between Quakes Below Antarctic Glaciers and Ocean Tides

Aug 21, 2012 08:01 AM EDT
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A new research suggests a possible link between earthquakes below Antarctic glaciers and ocean tides.

A team of researchers studied David Glacier, a large glacier that is located in East Antarctica, over a period of nine months between 2002 and 2003. They analyzed the seismic data and identified 20,000 stronger earthquakes that occurred during this period.

They noticed that all earthquakes occurred during a time gap of 25 minutes between each quake. When the glaciers hit an obstacle, they slowed down or stopped their movement until they gained enough mass to overcome the obstacle. During this time, the glaciers make an abrupt forward movement causing an earthquake.  This kind of a stick-slip phenomenon causing a jerking motion occurs randomly, when two objects slide against each other. But the experts found that the quakes below the David glacier occurred in periodic time intervals, a report in Phys.org said.

By comparing the seismic data with earlier recordings, they found that there was a correlation between the shaking event and the ocean tides. "The fact these events exist is fairly surprising," researcher Lucas Zoet, a glaciologist at Pennsylvania State University, told OurAmazingPlanet. "This type of seismic behavior had not been observed before in Antarctic outlet glaciers, so one main challenge was just to categorize it initially."

Ocean tides are said to influence the flow of glaciers. While glaciers tend to flow slowly during high tides, they speed up during low tides. "When the tide is high, the speed goes down a little bit, and that reduction in speed results in changes to the spacing of the seismicity," Zoet said.

"The high tide causes events to become spaced further in time, while the low tide causes them to become closer," he added.

Researchers pointed out that ocean tides might play a significant role in other glacial areas as well. They added that the increase in sea levels might also cause changes in seismic activity.

The findings of the study are published in the journal NatureGeoscience

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