Scientists have discovered that the West Antarctic Ice Sheet is suffering from massive ice-quakes measuring around 7 on the Richter scale twice a day. The scientists traced the source of the quakes to the Whillans Ice Stream, a glacier which measures 100 km across and 1 km thick.

It may seem strange that the quakes have been occurring for quite some time and the people working on the ice sheet haven’t noticed but the reason is quite simple – the quakes are a very slow event. In standard earthquakes, the energy is released in a few seconds causing massive tremors; these ice quakes are releasing their in around 20 minutes therefore the movement of the earth is virtually unnoticeable.

The first time that the ice quakes were noticed was three years ago when Douglas Weins, a seismologist at Washington University, analysed data from 43 sensors spread across Antarctica. He was hoping to pick up faint signals which would lead him towards previously undiscovered fault lines, however he increasingly saw vibrations emanating from the same Antarctic area.

In 2004, a second scientist, Sridhar Anandakrishnanm placed some sensors on the Whillans Ice Stream to measure it’s flow as the stream was known to have strange behaviour – usually, a glacier will move forwards in a continuous fashion; The Whillans Ice Stream is at a standstill for much of the time and surges forward around half a metre twice daily as the ocean tides lift and lower the part of the ice that extends into the Ross Sea.

By analysing the two sets of data side by side, the researchers realised that the surges made by the glacier matched the seismology data suggesting that the ice quakes were caused by the ice grinding over a rough spot in the ice below the glacier.

The research here is important because finding the cause of ice quakes may help to better understand glacial movement and therefore garner a better understanding of how climate change might affect them.

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