Japanese tsunami causes breaking of Antarctic ice shelf

As Edward Lorentz once put it so eloquently in his Chaos Theory is that something as small as the flutter of a butterfly’s wing can ultimately cause a typhoon halfway around the world. Then what influence could something as large as the earthquake and subsequent tsunami in March that wreaked havoc on the Japanese mainland have around the world? As it turns out the quake that could be felt as high up as the ionosphere had a visible effect on Antarctic ice some 13,600 kilometres away.

Flexing and breaking

Although not nearly as disastrous as the effect on heavily populated Japan the tsunami managed to break off icebergs totalling 125 square kilometres off the West Antarctica’s Sulzberger Ice Shelf. The findings published in the Journal of Glaciology show that the breaking of the Sulzberger shelf was caused by an hours to days long flexing of the ice, despite of a swell of no more than 30 centimetres.

First calving in 46 years

The basis of the study, a series of radar images from the European Space Agency’s Envisat satellite showed the first calving episode of the Sulzberger shelf in 46 years, about 18 hours after the earthquake occurred. The largest iceberg that was spotted measured 6.5 kilometres by 9.5 kilometres and was about 80 metres thick.

No protection from sea ice

Some theories say that sea ice can protect against the calving of icebergs from Antarctica, by dampening swells that might cause calving, but in this sea ice case was absent. This buffering effect of sea ice was previously observed at the time of the Sumatra tsunami in 2004. However due to rising water temperatures around Antarctica the amount of sea ice decreases yearly, possibly removing this ‘protective barrier’ around the continent.


If anything this event is evidence that Earth systems are strongly interconnected; a tectonic effect causing the calving of icebergs more than 13,000 kilometres away. One might wonder whether Earth’s ice shelves are even more sensitive to seemingly unrelated events than currently assumed.

© Jorn van Dooren | www.bitsofscience.org

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