Does it seem like there have been a lot of earthquakes lately? Scientists at NASA tell us that some earthquakes are powerful enough to shift the earth’s axis, making the earth spin slightly faster. They estimated that after the recent earthquake in Chili, the earth is spinning 1.26 millionths of a second faster each day.

A large shift in the earth’s mass can affect our planet’s rotation. Usually the change in rotation is tiny, but sometimes it can actually be measured. Shifts in the earth’s mass are not only caused by earthquakes, but can also happen due to changes in ocean currents or the atmosphere.*

The Chilean earthquake was one of the largest we have seen in a century. It was caused because, at some time in the past, one of the earth’s plates slid under another plate. The two plates became wedged together. Eventually the energy under one of the plates became stronger than what held them together and the plates moved. This changed the earth’s axis by three inches, causing the earth to spin slightly faster.

Have you missed the 1.26 millionths of a second in each day?

* Naik, Gautam, 2010. “Temblor Tilts Earth by Inches” Wall Street Journal (online edition). http://online.wsj.com/article/SB10001424052748704486504575098083228068948.html (posted March 3, 2010).