Wednesday, 3 March 2010

The days are getting shorter

From Sky News
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 disaster. 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. 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.

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.

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