How the Japan Earthquake Shortened the Earth Day | Japan Earthquake & Tsunami | Natural Disasters, Earth Tilt & Earth's Axis | Space.com: "By changing the distribution of the Earth's mass, the Japanese earthquake should have caused the Earth to rotate a bit faster, shortening the length of the day by about 1.8 microseconds.
The 8.8-magnitude earthquake in Chile last year also sped up the planet's rotation and shortened the day by 1.26 microseconds. The 9.1 Sumatra earthquake in 2004 shortened the day by 6.8 microseconds.
And the impact from Japan's 8.9-magnitude temblor may not be completely over.The weaker aftershocks may contribute tiny changes to day length as well."
