Shorter days

        NASA said the massive earthquake that struck Chile may have shifted the Earth's axis and created shorter days, 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. NASA's scientists Benjamin Fong Chao said any event that involves the movement of mass affects the Earth's rotation. It was determined that the quake should have moved the Earth's figure axis about 3 inches (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. Such changes aren't unheard of.