(Courtesy of Alan Buris – NASA Jet Propulsion Laboratory, March, 2011 press release.)
The 9.0 magnitude quake was caused when the Pacific tectonic plate shifted under the North American plate, which moved Eastern Japan towards North America by about 13 feet (observed on NASA’s before and after photos below).
Shorter Days
Using a United States Geological Survey estimate for how the fault responsible for the earthquake slipped, research scientist Richard Gross of NASA’s Jet Propulsion Laboratory, performed a preliminary theoretical calculation of how the Japan earthquake, the fifth largest since 1900, affected Earth’s rotation. His calculations indicate that by changing the distribution of Earth’s mass, the Japanese earthquake should have caused Earth to rotate a bit faster, shortening the length of the day by about 1.8 microseconds.
Shifted Axis
The calculations also show the Japan quake shifted the position of Earth’s figure axis by about 17 centimeters (6.5 inches), towards 133 degrees east longitude, sinking Japan downwards about 2 feet. Earth’s figure axis is different from its north-south axis, both are offset by about 10 meters (about 33 feet). This shift in Earth’s figure axis will cause Earth to wobble a bit differently as it rotates, but it will not cause a shift of Earth’s axis in space. Both calculations will likely change as data on the quake are further refined.
Affects on our daily lives?
Gross said the changes in Earth’s rotation and figure axis caused by earthquakes should not have any impacts on our daily lives. “These changes in Earth’s rotation are perfectly natural and happen all the time,” he said. “People shouldn’t worry about them.”
The 9.0 magnitude quake was caused when the Pacific tectonic plate shifted under the North American plate, which moved Eastern Japan towards North America by about 13 feet (observed on NASA’s before and after photos below).
Shorter Days
Using a United States Geological Survey estimate for how the fault responsible for the earthquake slipped, research scientist Richard Gross of NASA’s Jet Propulsion Laboratory, performed a preliminary theoretical calculation of how the Japan earthquake, the fifth largest since 1900, affected Earth’s rotation. His calculations indicate that by changing the distribution of Earth’s mass, the Japanese earthquake should have caused Earth to rotate a bit faster, shortening the length of the day by about 1.8 microseconds.
Shifted Axis
The calculations also show the Japan quake shifted the position of Earth’s figure axis by about 17 centimeters (6.5 inches), towards 133 degrees east longitude, sinking Japan downwards about 2 feet. Earth’s figure axis is different from its north-south axis, both are offset by about 10 meters (about 33 feet). This shift in Earth’s figure axis will cause Earth to wobble a bit differently as it rotates, but it will not cause a shift of Earth’s axis in space. Both calculations will likely change as data on the quake are further refined.
Affects on our daily lives?
Gross said the changes in Earth’s rotation and figure axis caused by earthquakes should not have any impacts on our daily lives. “These changes in Earth’s rotation are perfectly natural and happen all the time,” he said. “People shouldn’t worry about them.”
hilitehead 
elaborate?