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The powerful earthquake that killed hundreds of people in Chile on Saturday probably shifted the Earth's axis and made days slightly shorter, a Nasa scientist has said.

Richard Gross, a research scientist at Nasa's Jet Propulsion Laboratory in California, calculated how much the axis may have changed in position following the the disaster.

More than 700 people died and two million are estimated to have been affected by the 8.8-magnitude tremor and subsequent tsunamis.

The quake, the most powerful to hit the nation in 50 years, sent shockwaves out from the epicentre 70 miles from Chile's second city, Concepcion.

Buildings and roads collapsed and 500,000 homes have been left severely damaged.

Six aid workers died when a plane carrying them to Concepcion crashed.

The team was on its way to help organise accommodation for those left homeless by the disaster.

Soldiers were sent to patrol Concepcion's streets after mobs set fire to shops and started looting them, hindering attempts to rescue survivors.

If the planet's axis did shift by 8cm during the quake, days would have shortened by 1.26 microseconds, Mr Gross calculated.

A microsecond is one-millionth of a second.

Earth days are 24 hours long because that is the amount of time it takes the planet to make one full rotation on its axis, so shifting the axis would affect rotation.

The quake shifted the Earth's axis by even more than the 9.1-magnitude tremor off Indonesia that started the deadly tsunami in Asia in 2004, according to Mr Gross.

This was partly because the fault line responsible for the quake in Chile "dips into Earth at a slightly steeper angle than does the fault responsible for the 2004 Sumatran earthquake", he said.

The different angle made Saturday's tremor more effective at moving Earth's mass vertically and shifting the planet's axis, Mr Gross continued.

The 2004 quake in Asia, which killed hundreds of thousands of people, caused the Earth to move by around 7cm.

It chopped an estimated 6.8 microseconds off the length of a day, Nasa said.

Earl wrote:Ah, yes, those microseconds seem to last so long.

i_like_1981 wrote:

Earl wrote:Ah, yes, those microseconds seem to last so long.

To me it's not the amount of time it changed the length of the day by, more the fact that the earthquake was powerful enough to affect the Earth's axis to the extent where it had an effect of the day length. The shocking thing is it actually made the day a bit shorter! 8.8 on the Richter Scale is bloody powerful. I can't imagine how it would feel to put up with that for even a couple of seconds...

Best regards,
i_like_1981

Yahoo News wrote: Earth days are 24 hours long because that is the amount of time it takes the planet to make one full rotation on its axis, so shifting the axis would affect rotation.

ABC News wrote: Quake shortened Earth's days
By Simon Lauder
Posted Wed Mar 3, 2010 10:41am AEDT

...

He, (Dr David Kerridge from the British Geological Survey), says the quake was strong enough to alter the distribution of the earth's mass and therefore speed up the rotation of the planet.

...

He says people can understand how the shift speeds up the earth's rotation if you imagine an ice skater spinning on an axis that runs from her head to her toes.

"When she puts her arms out, then she rotates quite slowly. When she brings her arms in, she begins to rotate much faster," he said.

"That's because she is decreasing her moment of inertia by bringing in her arms, by bringing the mass closer to the rotation axis. But angular momentum stays the same, which means rotation rate increases.

"Here it's the same kind of effect, but a very, very tiny one given the huge mass of the earth and the very small changes that have been made at the surface."

NASA geophysicist Richard Gross has told the Bloomberg newsagency the quake sped up the rotation of the earth enough to shorten the day by an estimated 1.26 millionths of a second.

i_like_1981 wrote: So, the Earth's mass has been redistributed and that is the real cause of the slight shortening of the Earth's day. And I use the word "slight" in its very strongest content. It really is worth nothing at all, but I guess the fact it affected a universally-known measurement of time even in a minuscule way is enough to make mouths drop.

i_like_1981 wrote: By the way, what gave you the idea for your username? I'm quite interested to know.