Earth Rotation Speed
March 16, 2011 by staff
Earth Rotation Speed, The earthquake of magnitude 8.9 in Japan March 11 Earth Day shortened by .8 millionths of a second, according to NASA scientists. Earth tilts on its axis more than 23.5 degrees, as before. But since March 11 earthquake, the Earth rotates faster than before, and our day is slightly shorter, from sunrise to sunset.
This change is so small that sophisticated instruments cannot detect it. Instead, a team of laboratory scientists from NASA Jet Propulsion calculated the variation of the Earth spin, using computers and seismic data.
Beth Lebwohl EarthSky spoke with Richard S. Gross, leader of the team and senior researcher at the Laboratory of NASA’s Jet Propulsion. His group has used the seismic data showing the amount of slippage in the line of fault necessary to create the earthquake in Japan in order to calculate the mass movement inside the Earth and subsequent changes in rates of the Earth turning.
Imagine a figure skater spinning. As she moves her arms around her body, she spins faster. The Earth is like that. If the mass of the Earth is closer to its axis of rotation, the planet will run faster.
Overall, the Earth’s rotation axis is tilted at an angle of 23.5 degrees to the orbital plane of the Earth in which moves around the sun. This tilt causes our seasons, and this inclination has not changed. What has changed the orientation of the solid Earth with respect to tilt of our planet? In other words, the earthquake rearranged mass of the Earth, bringing a bit more mass closer to the axis of rotation of the Earth, causing the earth to turn a bit faster and the length of the day shorter. Mr. Gross:
This change does not affect the (degree) of the inclination of the axis of the Earth in space, or the Earth’s orbit around the sun. Tilt of the earth one-way or the orbit may be affected is if an outside force – such as an asteroid – hits the Earth. These are internal processes – earthquakes or winds or currents. They can change how the mass of the Earth is balanced. The Earth is a great solid body rotation. All that is reasonable to what is happening because only a very small change. Earth is in fact a very stable system.
EarthSky Gross said that if a change in the Earth’s axis and the rotation speed may seem striking, perhaps even frightening, the Earth moves slightly all the time, mostly because of atmospheric and ocean currents.
This is a perfectly natural movement of the Earth, and the greatest cause of this movement is the changes in atmospheric winds and changes in ocean currents. Winds and currents carry with them a lot of energy and that energy can be exchanged with the solid Earth to cause the rotation of the Earth to change.
If you were to stop the wind completely, Gross said, you could change the length of the day the earth about milliseconds. He added that other earthquakes have also changed Earth’s axis, for example, the earthquake in Chile in February 2010, an earthquake and even stronger in Chile in.
The largest earthquake that occurred in Earth’s history was the earthquake of 1960 in Chile. I made the same calculation for this earthquake (like the earthquake in Japan 2011 and 2010 earthquake in Chile) and, according to my calculations, the 1960 earthquake would have shortened the duration of the day 8 microseconds.
He explained that his figures on the displacement caused by the earthquake in Japan are preliminary. His team is still working on the calculations.
We look at the comments at this time to see if the predicted effects are indeed observable, but it will take some time for us to reduce the data – that is, to reduce the effects of the atmosphere and oceans – to see much smaller effects caused by the earthquake. But if we succeed, this will be the first time we see an effect verified the earthquake on the Earth’s rotation.
The magnitude 8.9 earthquake that hit northern Japan on Friday not only changed the balance of the planet and spin of the Earth changed. He also took the coast of the island nation of Japan. Global positioning stations closest to the epicenter of the earthquake jumped to the east up to 13 feet. Meanwhile, our day got shorter by 1.8 millionths of a second.
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