An earthquake can shorten the length of a day.
On February 27, 2010, an earthquake in Chile that registered an 8.8 on the Richter scale may very have shortened the length of a day on Earth. Researchers computed the change to be as much as making a day 1.26 microseconds shorter. In addition, the quake also shifted the Earth on its axis. The Earth’s axis moved 2.7 milliarcseconds (which is actually a unit of angular measurement, not time). That’s the equivalent of about 8 centimeters or three inches.