Scientists explain scale of Japanese tsunami

Tsunamis are caused by earthquakes under the seabed. Some tsunamis – including the disaster that hit Japan last year – are unexpectedly large. Cambridge scientists suggest that their severity is caused by a release of gravitational energy as well as elastic energy.

Scientists at Cambridge University have developed a model that may show why some tsunamis – including the one that devastated Japan in March 2011 – are so much larger than expected. The Japanese tsunami baffled the world’s experts as it was far bigger than might have been anticipated from what is known about the deep sea earthquakes that create long waves out in the ocean.

In a paper published last week (24 August 2012) in the journal Earth and Planetary Science Letters, Professors Dan McKenzie and James Jackson of Cambridge’s Department of Earth Sciences describe for the first time the added factor that may have made this tsunami so severe: a huge collapse of soft material on the sea bed resulted in a far greater movement of water than would have been caused by the earthquake alone.


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Image: A wave approaches Miyako City from the Heigawa estuary in Iwate Prefecture
Credit: REUTERS/Mainichi Shimbun


Reproduced courtesy of the University of Cambridge

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