Japan quake causes day to get a wee bit shorter

[March 12, 2011]  WASHINGTON (AP) -- You won't notice it, but the day just got a tiny bit shorter because of Friday's giant earthquake off the coast of Japan.

NASA geophysicist Richard Gross calculated that Earth's rotation sped up by 1.6 microseconds. That's because of the shift in Earth's mass caused by the 8.9-magnitude earthquake. A microsecond is one-millionth of a second. That change in rotation speed is slightly more than the one caused by last year's larger Chile earthquake. But 2004's bigger Sumatra earthquake caused a 6.8-microsecond shortening of the day. The Japan quake is the fifth-strongest since 1900. [Associated Press; By SETH BORENSTEIN] Copyright 2011 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.