Earthquake Shortens Day
The earthquake that struck Chile on Saturday may have shifted the Earth's axis and created shorter days, according to scientists at Nasa. Richard Gross, a geophysicist at NASA's Jet Propulsion Laboratory in Pasadena, California, said the 8.8 magnitude quake could have moved the Earth's axis by 2.7 milliarcseconds (about 8cm) – enough to shorten a day by about 1.26 microseconds.
A large quake can shift huge amounts of rock and alter the distribution of mass on the planet. When that distribution changes, it changes the rate at which the planet rotates, which determines the length of a day. "The length of the day should have got shorter by 1.26 microseconds," Gross told the Bloomberg news agency. "The axis about which the Earth's mass is balanced should have moved by 2.7 milliarcseconds."