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Houses, cars and other debris are washed away by a tsunami in Kesennuma in Miyagi Prefecture, northern Japan, after strong earthquakes hit the area Friday, March 11, 2011. (AP Photo/Keichi Nakane, The Yomiuri Shimbun)

Houses are in flame while the Natori river is flooded over the surrounding area by tsunami tidal waves in Natori city, Miyagi Prefecture, northern Japan, March 11, 2011, after strong earthquakes hit the area. (AP Photo/Yasushi Kanno, The Yomiuri Shimbun)

A massive tsunami sweeps in to engulf a residential area after a powerful earthquake in Natori, Miyagi Prefecture in northeastern Japan March 11, 2011. (REUTERS/KYODO)

People make their way through a street clogged with debris in Sendai city, Miyagi prefecture March 12, 2011. (REUTERS/Yomiuri)

A member of the Japan Self-Defence Forces carries a man in Natori city, in Miyagi prefecture March 12, 2011. (REUTERS/Yomiuri)

Japan Earthquake Earth Rotation Speed

An earthquake measuring 9 on the Richter Scale (SR) that occurred in Japan on Friday (3/11/2011) causing the Earth's mass distribution changes because of plate movement and the collapse of rock in the Earth's skin. These affect the speed of rotation of the earth to be a little faster and humans have a shorter day. 

"By changing the mass distribution in the Earth, Japan earthquake resulted in the Earth rotates more quickly, shortening the day as much as 1.8 microseconds," said Richard Gross, geophysicist at NASA's Jet Propulsion Laboratory in Pasadena, USA, as reported by Space.com. Analysis before the quake affected only 1.6 microsecond rotational speed, but recent data suggest that the greater strength. 

However, the effect is much smaller than the old annual variation of Earth rotation. The length of one day or time of rotation of the Earth is 24 hours or 86,400 seconds. Long day for about 1000 microseconds this varies depending on season variation of Earth's mass distribution. 

Changes in the rotation by an earthquake like this is not the first time happening.Aceh Earthquake of 2004 for example, shorten the day as much as 6.8 microseconds. While the earthquake in Chile shorten the day 1.26 microseconds. 

Gross said that this change has not been completed. Aftershocks could also change the rotation. "Aftershocks could also change the rotation time. But because the power of smaller aftershocks, the effect is also smaller," he explained. 

In theory, Gross said, anything that affects the Earth's mass distribution will impact on the rotation. Earthquake reported little movement of the earth's rotation speed is typically about 1604 km / hour.