Washington: The massive 8.8 magnitude
earthquake that struck Chile may have shifted the Earth's axis
and created shorter days, scientists at NASA say.
The change is negligible, but permanent: Each day should
be 1.26 microseconds shorter, according to preliminary
calculations. A microsecond is one-millionth of a second.
A large quake shifts massive amounts of rock and alters
the distribution of mass on the planet.
When that distribution changes, it changes the rate at
which the planet rotates. And the rotation rate determines the
length of a day.
Richard Gross, a geophysicist at NASA's Jet Propulsion
Laboratory in Pasadena, California, used a computer model to
determine how the magnitude 8.8 quake that struck Chile on
February 27 that killed at least 711 people may have affected
the Earth, CNN reported.
He determined that the quake should have moved the
Earth's figure axis about 8 centimeters. The figure axis is
one around which the Earth's mass is balanced. That shift in
axis is what may have shortened days.
The magnitude 9.1 earthquake in 2004 that generated a
killer tsunami in the Indian Ocean shortened the length of
days by 6.8 microseconds.
PTI
First Published: Wednesday, March 03, 2010, 13:08