how chile's quake could have shortened a day: BBC news
NASA calculates the quake in Chile shifted mass to such an extent that it changed the rotation of the earth to shorten a day by one millionth of a second. Using the same mathematical model, the NASA team estimated the 9.1 Sumatran earthquake in 2004 shortened a day by 6.8 microseconds.
it's been happening since the beginning of time, but NASA doesn't think should affect any biological systems. learn, in colloquial terms, how the quake caused a change in mass distribution at BBC news.
How an earthquake could shorten a day