Computers, however, should be well-prepared to handle this fluctuation once it is introduced into the official time-keeping systems, given the existing systems for reconciling computer time with solar time.

The 9.0-magnitude quake -- the fifth-largest since 1900 -- has possibly shifted the Earth's mass, thereby changing its rotation and shortening the days by up to 1.8 microseconds per day, argues research scientist Richard Gross of NASA's Jet Propulsion Laboratory in Pasadena, California.

A microsecond is one-millionth of a second. While humans won't notice the shortened days, any resulting changes will eventually affect computers, which get their times readjusted through the periodic injection of leap seconds.

Gross used a model from the United States Geological Survey to calculate how the earthquake may have shifted the Earth's mass. He estimated that the Earth's figure axis (the axis about which Earth's mass is balanced) has been shifted by about 6.5 inches (17 centimeters) toward 133 degrees east longitude. This new distribution of weight may cause the planet to wobble differently than it did before, thereby shortening the time it takes to complete a 24-hour cycle.

Gross expects to refine his calculations as more data from the earthquake is recorded.