Richard Gross, a researcher from the Jet Propulsion Laboratory, NASA develop complex computer models to mengalkulasikan theoretically, how the earthquake in Japan, which is the fifth largest earthquake since 1900, affecting the Earth's rotation. 
Utilizing data from the United States Geological Survey, the calculation results indicate a change in Earth's mass distribution. Japan quake has made the Earth rotates slightly faster, and shorten the time in one day to 1.8 microseconds, or millionths of a second.
Calculations are made also shows that the axis of the Earth moves around 17 centimeters in the direction of longitude east. Change this shaft will make the Earth a little different movement. But it does not affect the position of Earth in space because the only external forces such as gravity of the Sun, Moon, and planets that could change that.
On the shortness of time in a day that has not reached 24 hours, as an illustration, a magnitude 8.8 earthquake that occurred last year in Chile, the time of the day has been cut by 1.26 microseconds and shift the axis of the Earth is about 8 cm.
In fact, using similar calculations are carried out after a magnitude 9.1 quake that struck Aceh in 2004, the time of the day was reduced by 6.8 microseconds due to shifting of the Earth's axis and shape of about 7 cm.
"Rotation of the Earth is constantly changing, and not only caused by the earthquake, but also influenced by other factors such as wind in the atmosphere and ocean currents," Gross said, as quoted by Science Daily, May 10, 2011. "How do earthquakes affect the rotation of the Earth depends on the scale, location, and how earthquakes occur," he said.
Gross mentions, within one year, time in a day can increase and also reduced by about one millisecond or 550 times larger than Japan's earthquake. Similarly, Earth's plates that can be shifted about 1 meter in one year due to various earthquake.
"Theoretically, anything that can redistribute the mass of the Earth will change the rotation of planet Earth," said Gross. "However, changes in the Earth's axis of rotation and should not affect our daily lives. This change is very natural and happen anytime. People do not need to worry, "he said.
Although it has been making a calculation, calculations made by Gross, both for rotation and the axis of the Earth, the result is likely to still change with the emergence of new data are more accurate about the phenomena that occur on Earth. (Umi)
• VIVAnews
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