How earthquake jolted the planet

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The Times
By Nigel Hawkes
Sumatra is thought to have moved by as much as 120ft and the Earth to have shifted on its axis



THE earthquake responsible for the Asian tsunami was so powerful that it changed the local geography, shifting islands and the mainland of Sumatra by as much as 120ft, American seismologists said yesterday.
The energy released by the quake was so huge that it may even have caused the Earth to wobble on its axis. Geophysicists are calling it a megathrust, the term used for the most powerful of changes in the Earth’s surface. Pressure built up over nearly two centuries was released in a single snap.

“That earthquake has changed the map,” Ken Hudnut, of the US Geological Survey (USGS), said. “Based on seismic modelling, some of the smaller islands off the southwest coast of Sumatra may have moved to the southwest by about 20 metres. That is a lot of slip.”

The northwestern tip of Sumatra may also have shifted to the southwest by about 36 metres (120ft), he said.

In addition, the energy released as the two sides of the undersea fault slipped against each other probably made the Earth wobble on its axis. “We can detect very slight motions of the Earth and I would expect that the Earth wobbled when the earthquake occurred due to the massive amount of energy exerted and the sudden shift in mass,” he said.

http://www.timesonline.co.uk/article/0,,3-1418302,00.html