WASHINGTON - The powerful earthquake that shook Chile on Saturday probably shifted the Earth's axis and made days slightly shorter, a NASA scientist said.

Richard Gross, a research scientist at NASA's Jet Propulsion Laboratory in California, calculated that the planet's axis would have shifted by eight centimeters (three inches) during the 8.8 magnitude quake, NASA said in a statement.

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

If, indeed, the planet's axis did shift by eight centimeters during the Chilean quake, days would have shortened by 1.26 microseconds, Gross calculated.

A microsecond is one-millionth of a second, so no need to adjust watches just yet.

The Chilean quake shifted the Earth's axis by even more than the 9.1-magnitude temblor off Indonesia that set off the deadly tsunami in Asia in 2004, Gross worked out.

That's partly because the faultline responsible for the earthquake in Chile "dips into Earth at a slightly steeper angle than does the fault responsible for the 2004 Sumatran earthquake" and is more effective at moving Earth's mass vertically and shifting the planet's axis.

The 2004 quake in Asia caused the Earth to move by around seven centimeters and chopped an estimated 6.8 microseconds off the length of a day, NASA said.