Sumatran quake sped up Earth's rotation
Michael Hopkin
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Natural disaster shaved millionths of a second off planet's day.

The devastating earthquake that struck the Indian Ocean on 26 December was so powerful that it has
accelerated the Earth's rotation, geophysicists have declared. They estimate that the shockwave
shortened the period of our planet's rotation by some three microseconds.

The change was caused by a shift of mass towards the planet's centre, as the Indian Ocean's heavy
tectonic plate lurched underneath Indonesia's one, say researchers at NASA's Jet Propulsion
Laboratory in Pasadena, California. This caused the globe to rotate faster, in the same way that a
spinning figure-skater accelerates by tucking in her arms.

The blast literally rocked the world on its axis, add Richard Gross and his NASA colleagues. They
estimate that Earth now tilts by an extra 2.5 centimetres in the wake of the jolt.

http://www.nature.com/news/2004/041229/full/041229-6.html
___________________________________________
Cynthia M. Daniels
Northwestern University
Biomedical Engineering Department
2145 N. Sheridan Rd.
Technological Institute, E310
Evanston, IL 60208
Ameer Lab: 847-491-7646
Email: [log in to unmask]

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