Chilean Quake May Have Shortened Earth Days

Mar 02, 2010
This view of Earth comes from NASA's Moderate Resolution Imaging Spectroradiometer aboard the Terra satellite.

(PhysOrg.com) -- The Feb. 27 magnitude 8.8 earthquake in Chile may have shortened the length of each Earth day.

JPL research scientist Richard Gross computed how Earth's rotation should have changed as a result of the Feb. 27 quake. Using a complex model, he and fellow scientists came up with a preliminary calculation that the quake should have shortened the length of an Earth day by about 1.26 microseconds.

Perhaps more impressive is how much the quake shifted Earth's axis. Gross calculates the quake should have moved Earth's figure axis (the axis about which Earth's mass is balanced) by 2.7 milliarcseconds (about 8 centimeters, or 3 inches). Earth's figure axis is not the same as its north-south axis; they are offset by about 10 meters (about 33 feet).

By comparison, Gross said the same model estimated the 2004 magnitude 9.1 Sumatran earthquake should have shortened the length of day by 6.8 microseconds and shifted Earth's axis by 2.32 milliarcseconds (about 7 centimeters, or 2.76 inches).

Gross said that even though the Chilean earthquake is much smaller than the Sumatran quake, it is predicted to have changed the position of the figure axis by a bit more for two reasons. First, unlike the 2004 Sumatran earthquake, which was located near the , the 2010 Chilean earthquake was located in Earth's mid-latitudes, which makes it more effective in shifting Earth's figure axis. Second, the fault responsible for the 2010 Chiliean earthquake dips into Earth at a slightly steeper angle than does the fault responsible for the 2004 Sumatran . This makes the Chile fault more effective in moving Earth's mass vertically and hence more effective in shifting Earth's figure axis.

Gross said the Chile predictions will likely change as data on the are further refined.

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User comments : 8

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Tuppu
Mar 02, 2010
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TheBigYin
4.8 / 5 (4) Mar 02, 2010
How many earthquakes will we need to make the Sony Playstation 3 clock tell the time properly?
Yes
not rated yet Mar 02, 2010
Are there quakes that effectively do the opposite and lengthen a day? Or do quakes only shorten days?
TheBigYin
not rated yet Mar 02, 2010
The articule isn't clear, but is it the reduced diameter of the earth causing the rotational speed to decrease due to conservation of angular momentum?
Yellowdart
Mar 02, 2010
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TheBigYin
not rated yet Mar 02, 2010
Increase the speed, thus shortening the days, I mean. Doh.
El_Nose
not rated yet Mar 02, 2010
No this is under 0.002 sec in 6 years
KB6
Mar 02, 2010
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KeitoTen
not rated yet Mar 02, 2010
Seems like the change in the tilt is a larger deal then the change in rotational speed.
lestat_B
not rated yet Mar 03, 2010
Great disaster over the century. I hope no one gets hurt by the Okinawa earthquake. Okinawa, and I think the rest of Japan is on Tsunami warning, but their buildings have to be built to withstand earthquakes. The Haitian earthquake was a bit of a fluke, but Japan, and the Pacific Rim in general, is the most earthquake prone area on earth, and the kind of damage that can easily be done takes a lot more than payday loans to clear up. That being said, it isn't the first quake, even the first 7.0 earthquake they’ve had, by any means, so they ought to be able to handle most of whatever gets thrown at them.

boldone894
Mar 03, 2010
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LouieN
not rated yet Mar 08, 2010
If it is true that this Chilean earth quake had changed the position of the figure axis causing it to shortened the length of an Earth day then what are it's effects to us? payday loans And how will that affect if the same quake would happen in the future?