According to this article, the Japanese quake caused the length of a day to decrease by 1.6 microseconds. They attribute it to an increase in the earth's mass. Someone is going to have to explain that one to me. How did the mass increase? Nothing is missing, just moved around. Do we have a physicist in the house?

Japan quake causes day to get a wee bit shorter
Published March 11, 2011
| Associated Press
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WASHINGTON – 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.