Chile Earthquake Altered Earth Axis, Shortened Day
Earthquake sped Earth's spin, figure skater style.
By speeding up Earth's rotation, the magnitude 8.8 earthquake—the fifth strongest ever recorded, according to the USGS—should have shortened an Earth day by 1.26 millionths of a second, according to new computer-model calculations by geophysicist Richard Gross of NASA's Jet Propulsion Laboratory in California.
For comparison, the same model estimated that the magnitude 9 Sumatra earthquake in December 2004 shortened the length of a day by 6.8 millionths of a second.
Gross also estimates that the Chile earthquake shifted Earth's figure axis by about three inches (eight centimeters).
Deviating roughly 33 feet (10 meters) from the north-south axis around which Earth revolves, the figure axis is the imaginary line around which the world's unevenly distributed mass is balanced.
To explain the