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How the earthquake in Chile could change Earth’s axis

The views expressed are those of the author and are not necessarily those of Scientific American.


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chile earthquake shorten days change earth axis rotationThe magnitude 8.8 earthquake that jolted Chile on Saturday was felt as far away as São Paulo. But NASA scientists are proposing that its repercussions are truly global in a geophysical sense: it likely shifted Earth’s axis by about eight centimeters.

Such a shift would have the effect of shaking as much as 1.26 microseconds off of Earth’s daily rotation, noted NASA Jet Propulsion Laboratory scientist Richard Gross in an agency release.

Those microseconds (each one millionth of a second) might not sound like a lot, and they probably will not change your sleep patterns or birthday, but they do accumulate. And, as such, the change will be permanent, over the decades and eons, it will eventually amount to a trickle of "lost" time. (If the scientists’ early estimates are on target, this quake’s impact, however, will take about 130,500 years to shear off a full minute.)

But with such a fine scale (microseconds and centimeters) working on such a big mass (Earth), how can scientists calculate these details? Gross spoke with Scientific American in January 2005 to explain the concept following the then-recent undersea earthquake that caused the Indian Ocean tsunami.

Put simply, "It’s what we call the ice-skater effect," David Kerridge, head of Earth hazards and systems at the British Geological Survey in Edinburgh, told Bloomberg News. "When she’s going around in a circle, and she pulls her arms in, she gets faster and faster. It’s the same idea with the Earth going around if you change the distribution of mass, the rotation rate changes."

This shift is hardly a one-time occurrence, however. "Any worldly event that involves the movement of mass affects the Earth’s rotation," said Benjamin Fong Chao of NASA’s Goddard Space Flight Center in Greenbelt, Md., in 2005, CNN reported.

If all of this change was from a magnitude 8.8 quake, could a bigger event shift the planet’s rotation even more? Yes, the NASA scientists reported. A larger event, however, doesn’t automatically translate into a bigger effect. The magnitude 9.1 Sumatra earthquake in 2004 is one such example. It was closer to the equator and occurred on a fault that has a shallower angle into Earth’s crust, both of which contributed to it having less of an impact on Earth’s axis despite its greater immediate magnitude. That the Chile fault runs at a steep angle and is located mid-hemisphere means that movement there throws more weight around as the world turns.

But, as Gross noted in his Scientific American interview, the massive shifts of Earth’s plates have far less of an influence on the axis than even the breeze. "Changes in winds have by far the greatest effect on the length of the day: their effect is actually about 300 times larger."

Image of South America from space courtesy of Wikimedia Commons/NASA/JPL





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  1. 1. jtdwyer 7:19 pm 03/2/2010

    This is so disappointing: another article whose title refers to a news headline as if the sky is falling. However, reading this brief report, the impact of this earthquake is proportional to others, which generally continuously occur at fairly regular intervals, and is less than the impact of atmospheric motion (i.e., breezes). So why did I read this with such anticipation of doom created by the title, when it turns out to be a butterfly flapping its wings?

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  2. 2. scasagra 7:27 pm 03/2/2010

    Interesting. Re-reading the title is very neutral, but I’m sure the editor knew it will trigger dooms day thoughts on the reader and push for it. What causes the biggest dissapointment is at the end: the fact that wind influences more! Although I didn’t know these 2 things

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  3. 3. Mickey 7:38 pm 03/2/2010

    WILL THE SHIFTING OF THE EARTH’S AXIS AFFECT THE WEATHER?

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  4. 4. Mickey 7:40 pm 03/2/2010

    WILL THE SHIFTING OF THE EARTH’S AXIS AFFECT THE WEATHER?

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  5. 5. jtdwyer 8:55 pm 03/2/2010

    Mickey – ITS THE BUTTERFLIES OF DOOM!

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  6. 6. cablamblah 8:59 pm 03/2/2010

    this article is completely bogus. basic grade school physic proves its wrong. For example if a baseball is sitting on the ground, it does not move by itself. only an outside force can affect its ‘position’. nothing the baseball does on its ‘own’ can affect it position because any force ‘self created’ has an equal and opposite reaction upon the ‘self’. same with the earth. unless an outside force. ie. a comet or other et event collides with the earth its ‘self evident’ position remains uneffected. the energy to create and released from the quake came from another part of the earth having both equal and opposite reactions, meaning that any force an earthquake could potentional produce would be counteracted by an equally powerful force else where on the planet, thereby keeping the earths postion constant as ever.

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  7. 7. cablamblah 9:00 pm 03/2/2010

    this article is completely bogus. basic grade school physic proves its wrong. For example if a baseball is sitting on the ground, it does not move by itself. only an outside force can affect its ‘position’. nothing the baseball does on its ‘own’ can affect it position because any force ‘self created’ has an equal and opposite reaction upon the ‘self’. same with the earth. unless an outside force. ie. a comet or other et event collides with the earth its ‘self evident’ position remains uneffected. the energy to create and released from the quake came from another part of the earth having both equal and opposite reactions, meaning that any force an earthquake could potentional produce would be counteracted by an equally powerful force else where on the planet, thereby keeping the earths postion constant as ever.

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  8. 8. fisixisfun 10:04 pm 03/2/2010

    You clearly have little understanding of what is going on here. The earthquake accelerated the Earth’s rotation rate by making the radius of the Earth a little bit smaller, so by conservation of angular momentum it must speed up to compensate.

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  9. 9. krabcat 12:06 am 03/3/2010

    the gave a prety simple explanation on how this works red the 5th paragraph, even beter here it is

    Put simply, "It’s what we call the ice-skater effect," David Kerridge, head of Earth hazards and systems at the British Geological Survey in Edinburgh, told Bloomberg News. "When she’s going around in a circle, and she pulls her arms in, she gets faster and faster. It’s the same idea with the Earth going around if you change the distribution of mass, the rotation rate changes."

    Link to this
  10. 10. OlieV 12:28 am 03/3/2010

    <a rev="vote for" title="Chile earthquake alters Earth axis, makes days shorter" href="http://personalmoneystore.com/moneyblog/2010/03/02/chile-earthquake-earth-axis/ ">Chile earthquake</a> has altered Earths’ axis. NASA is already talking about it. Think about it this way – the actions of a planet are inextricably linked to its mass, and an earthquake affects it. So we lose a few milliseconds? Big deal – it doesn’t mean you should get payday loans to build a shelter and get a tin foil hat. According to estimates, our day shortened by less than 2 milliseconds (2 millionths of a second), but the 2004 earthquake in Indonesia set us back over 6 milliseconds. Earthquakes happen all the time – and there’s a few in the 7 to 8 range every year.

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  11. 11. dhart 1:25 am 03/3/2010

    It just bugs me that JPL would equate arcseconds with length. It would have to be a length subtended at a distance to make any sense.

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  12. 12. gandrews777 1:29 am 03/3/2010

    The more critical fact is that the axis shifted 3 inches. The angle of the axis has a great affect on our weather. So, what will be the affect? Heating, Cooling? So small it would be impossible to measure?

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  13. 13. gandrews777 1:31 am 03/3/2010

    Doesn’t a shift in the earth’s axis affect the weather?

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  14. 14. jtdwyer 3:59 am 03/3/2010

    gandrews777 – Yes, in this case imperceptibly. Significant shifts in the Earth’s axis of rotation’s alignment with the Sun changes the amount of thermal energy received at any location on the Earth’s surface. However, the total amount of thermal energy received by the Earth is unchanged by these axial shifts.

    The article states that the shift caused by this earthquake along with all other past and future earthquakes is less significant the the shift produced by winds blowing in the atmosphere. No mention was made of the potential shift produced by ocean currents.

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  15. 15. JamesDavis 6:51 am 03/3/2010

    Interesting, but too basic and the facts are a rehash. Maybe SciAm should take another look at their editor and reporters. I hain’t gonna go pointing no fingers, but I don’t think they have a two good an educational.

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  16. 16. Muso 7:36 am 03/3/2010

    Interesting and I wonder what Einstein would make of this as per his interview at http://myamazingpeople.com/en/1050/albert-einstein-new-bioview/

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  17. 17. old paint 8:49 am 03/3/2010

    How does this affect the equitorial plane and the wobble effect?

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  18. 18. ronestoquia 9:21 am 03/3/2010

    I may have missed the explanation on its effects on the north and south poles or Alaska. If it has the same effect, I am not sure if Sarah Palin needs to reset her alarm clock or have to work 1.26 microseconds more .

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  19. 19. ETHEL 12:00 pm 03/3/2010

    My hobby is the study of the science known as geology. I would like more information from the world of professional Geologists regarding the interplay of recent severe earthquakes, subsequent tidal waves, and how this is impacted by volcanic activity in the Circle of Fire of the Pacific Ocean Regions. Is any one making predictions of the why or how?

    I of course realize prediction is not foretelling. And I would like more information on how this planet Earth rights it axis following such major earthquakes. As a hobbyist it challenges me to think that as the Earth naturally rights its axis we will see proof positive that GREAT God Made Disasters can be out done by a simple act of a tree growing and displacing water, wind, fire and soil.

    Thank you

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  20. 20. Spoonman 12:22 pm 03/3/2010

    @cablamblah: your model is flawed, which is why it’s a fail. The Earth is not a baseball in this scenario, it’s one of those wind-up vibrating "bumble balls" or whatever they’re called. When the (internal) motor’s in effect, the ball will roll and bounce all over the floor without outside intervention.

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  21. 21. jtdwyer 12:59 pm 03/3/2010

    ETHEL – I was educated in Viet Nam and have no accreditation, but as a reasonable person I would expect that, relative to the Earth’s timescales, any affects of this earthquake on the wobble effect of the rotational axis and the flow rate of tectonic subducion should be localized in time and space and generally comparable to the affects of all past such events. While one earthquake may cause the axis to move in one direction, other earthquakes may cause it to move in other directions. If a sequential earthquake storm should occur along a major crustal fault the localized affects would be cumulative.

    You make an excellent point that the rotational momentum of the Earth, just like the gyroscope I played with as a child, will tend to mitigate against any force applied to it. That its rotational velocity is also affected must also be considered. These considerations exceed my capabilities of reason and certainly my ability to formulate and calculate, so I won’t comment further. Of course any comments are speculative until necessary investigations have been completed, even NASA’s, which were undoubtedly based on the predictions of an unproven geophysical simulation model.

    As you point out, it would be most informative if the article’s author had sought out even speculative comments to NASA’s statement from subject area experts – professional geologists.

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  22. 22. art_cali 5:26 pm 03/3/2010

    THIS IS THE BEGINNING OF THE END FOR HUMAN LIFE (2012)

    Link to this
  23. 23. Jamie 7:06 pm 03/3/2010

    Will we die earlier than we were supposed to?

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  24. 24. Jamie 7:07 pm 03/3/2010

    Will we die earlier than we were supposed to?

    Link to this
  25. 25. Jamie 7:09 pm 03/3/2010

    How do you know we will die in 2012

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  26. 26. John Spraggs 1:05 am 03/4/2010

    It occurs to me that the rapid change during the earthquake was merely the opposite of the slowly accumulated opposite distortion which would in the end, along with other earthquakes, cancel each other out. Neither the ice skater nor the earth’s crust have a way to continuously contract.

    Variations in ocean and air movements cause continuous changes in rotation which eventually average out.

    I would expect that the melting of land glaciers in Greenland and Antarctica would slow the earth and given that Greenland is off-axis, shift the poles some small amount.

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  27. 27. KittyKorn2009 8:05 pm 03/4/2010

    Cablamblah, your example is the one that is bogus here. The baseball to which you refer is a STATIONARY object. Earth is already in motion…so a better example would have been a top spinning on a table. That comparison should make you able to see for yourself what NASA and others are saying about this event. Hope this helps.

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  28. 28. KittyKorn2009 8:07 pm 03/4/2010

    CABLAMBLAH, it is your post that is erroneous. (hope this didn’t post twice; had a glitch the first time) Anyway, the baseball to which you refer is STATIONARY. A better example would have been using a spinning top on a table. With that illustration, perhaps you can see more clearly what NASA and others are saying. Hope this helps.

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  29. 29. jimhenson 8:08 pm 03/4/2010

    Whenever an earthquake occurs, it will either increase or decrease the rotation time of the earth, but nobody will ever know which it will be. 1.6 microseconds is just a guess, and is it longer or shorter? There are so many cumulative effects, like the gravity from passing asteroids. The thin brittle layer on the surface called the crust moves more, then the dense interior. What a stupid story to make the headlines. the earth’s mass is constant, and a very tiny change in time by even this earthquake is about the same as 1 weeks worth of meterites landing on earth and increasing the mass of the earth.

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  30. 30. Dr. Strangelove 8:23 pm 03/4/2010

    In H2G2s famous words: DONT PANIC
    The world will not end in 2012
    Unless an advanced alien civilization builds an intergalactic superhighway and the galactic president mistakenly signs earths demolition order for an autograph LOL

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  31. 31. frankboase 3:25 am 03/5/2010

    Didn’t l read very recently that a super accurate ‘clock’ has been developed,zillions of bucks down the tube. Why because
    this earthquake shows us again that time is relative.

    Link to this
  32. 32. Wayne Williamson 7:33 pm 03/5/2010

    this should mean that all the gps sats in orbit have to be resynced right….

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  33. 33. jtdwyer 8:04 pm 03/5/2010

    Wayne Williamson – Now that’s a good question – just how big a deal is this, anyway?

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  34. 34. Solfeggio Sound Source 3:13 pm 03/6/2010

    Lightworkers and evolved souls have been talking about this shift for a couple of decades. The earth and the Universe are changing. This was all predicated by the Mayans hundreds of years ago. 3D fear based reality cannot control what is going any longer. The Earth and all who reside upon her are raising their vibrations. We are truly at the dawn of entering a new dimension, a new consciousness. 3D consciousness as we know it is finished. We are presently raising our vibrations into a 4 dimension of consciousness – and soon to arrive in the 5th dimension. Open up your minds and enjoy the ride. There is nothing to fear!

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  35. 35. fisixisfun 11:17 pm 03/11/2010

    @Solfeggio Sound Source: You’re kidding right? Earthquakes happen all the time, they’ve been doing it on our planet for over 4 billion years, the recent ones mean nothing except some bad times for the people unfortunate enough to be where they happened. The Mayans had many fancy calendars, this whole "Mayan prophecy" idea is based on the fact that one of their longer calendars runs out on 12-21-12. But guess what? The calendar at my house ran out on 12-31-09, and yet we’re still here. Also, it’s not even known if 12-21-12 is really the end of their calendar, the reason people say that is that the Mayans had a thing for the numbers 13 and 20, and that date is the end of the 13th cycle of the next largest unit in their calendar, but it is unknown if they intended the rollover to happen then or at the end of the 20th cycle, which is several thousand years away. But then again, apocalypses thousands of years away don’t make any money in the present. The odds of something catastrophic happening on 12-21-12 are remote, no greater than on 12-21-13, or 12-31-09, or any other date within a few years of then.

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  36. 36. aresnans 4:00 pm 03/28/2010

    Yes the balls has molten iron which doesn’t interact with any gravity waves. The orbiting moon has no effect on the gravitational waves affecting the earth’s oceans. Hence, there are no tides.

    Cablahblah here is a hint: Your grade school physics knowledge is highly flawed. Don’t pass go, do not receive GED. My good friend in High School shared this same incorrect datum. It shattered his understanding when I sat him in a rotating chair with wheels, on level ground and told him to move himself without touching the ground. Equal opposite reaction would mean he would not be able to move or start rotating. Hence the theory for impulse drive is plausible even in zero gravity. Go try it and explain it with grade school physics. Remember friction is more or less a constant.

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