Chile quake moved Earth's axis, shortened days:
scientist
WASHINGTON (AFP) - – 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.
