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Your Day Feel Shorter? Blame Chile's Earthquake


The earthquake that struck Chile was so powerful that it appears to have jolted Earth's axis into a new position and increased our planet's rotation speed.

Calculations by a research scientist at NASA's Jet Propulsion Laboratory indicate the earthquake shortened the length of a day on Earth by more than one-millionth of a second.

The U.S. space agency's Richard Gross used a complex mathematical model to simulate the earthquake's effect. He estimates that our days are now 0.00000126 seconds shorter than they were last week. That's 1.26 microseconds, or millionths of a second, and Gross says the change will be permanent.

Earth's axis also was pushed about eight centimeters away from its normal position by the earthquake on Saturday - one centimeter more than the displacement produced by the mighty Sumatra earthquake of December 2004.

The Indonesian earthquake, measured at a magnitude of 9.1, was much more powerful than the 8.8-magnitude jolt that hit southern Chile. However, Gross says the Chilean quake shook Earth's axis even more than the catastrophic shock in Indonesia that sent huge tsunamis racing across the Indian Ocean. This was because the two earthquakes' different positions on the globe, as measured in distance from the equator.

Also, the fault in Earth's crust that produced the February 27 earthquake had a steeper vertical angle. Earth wobbles on its axis in response to the sudden shift of mass that occurs during a huge earthquake, and the angle of the Chilean fault intensified the effect of last week's temblor.

Gross says his calculations cannot be verified, because even the most careful observation of the length of a day is not accurate below five millionths of a second.

The space agency explained the scientist's work on its Web site at www.jpl.nasa.gov/news/features.cfm?feature=2504

Some information for this report was provided by AFP and Reuters.

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