Chile Quake Shifted Earth's Axis, Shortened the Length of a Day

By Smriti Rao | March 2, 2010 11:03 am

Earth-North-America-cloudsThe devastating earthquake in Chile that killed almost 700 people probably also shifted the Earth’s axis, say NASA scientists, permanently making days shorter by 1.26 microseconds. But since a microsecond is one-millionth of a second, you may not have noticed.

Richard Gross, a geophysicist at NASA’s Jet Propulsion Laboratory, says he has done the calculations. Gross says the earthquake, which measured 8.8 on the Richter scale, moved large amounts of rock, altered the distribution of mass on the planet, and moved the Earth’s axis by about 2.7 milliarcseconds (about 8 centimeters or 3 inches). The change in axis directly impacts Earth’s rotation, and the rate of the planet’s rotation determines the length of a day.

To explain this phenomenon, scientists used an ice skating analogy: When a skater spins on ice, he draws his arms closer in to his body to spin faster, because the speed of his rotation is dependent on the way mass is distributed across his body.

Scientists point out that the duration of a day can change depending on different geological events.

CNN reports:

The magnitude 9.1 earthquake in 2004 that generated a killer tsunami in the Indian Ocean shortened the length of days by 6.8 microseconds.

On the other hand, the length of a day also can increase. For example, if the Three Gorges reservoir in China were filled, it would hold 10 trillion gallons (40 cubic kilometers) of water. The shift of mass would lengthen days by 0.06 microsecond, scientists said.

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Related Content:
80beats: Why Chile’s Massive Earthquake Could Have Been Much Worse
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Image: iStockphoto

  • Katharine

    The NIST will not be pleased.

  • martin nix

    Where did all that energy go? All that 1.2 microsecond? I am going to tell you it went into the Earth’s core, which spins AT IT’s OWN RATE.Geologist just assume the Earth’s Solid Core is always in the center…it is NOT.It bounces around, and moves around in a liquid pool of lava.The Earth’s Core is about the same size of the moon, and the moon influences it’s location from gravity.In fact, the moon has a slight variation in it’s orbit, and noone knows why. I do, it is being pulled by the Earth’s Core. If you know the exact location of the moon, you know the location of the Earth’s Core, if you know both YOU CAN PREDICT WHERE THE NEXT BIG ONE IS GOING TO BE. What happen is the Earth’s Core bounced against the Andes Mountains, and triggered plate technonics.The movement of the core is the trigger, plate technonics is the loaded “gun”. Technonics force is Lateral, the bouncing ball is Horizontal. Like the moon which orbits West to East (the exact opposite of the sun), the Earth’s Core rotates West to East. It is no accident that this happen about 30 days after Haiti. It is no secret the moon has influence on earthquakes, just that noone seems to understand the interaction between the moon and the movement of the Earth’s Core. In fact, the Earth’s Core is like a planet within a planet. (mama earth is pregnant). Geologist disagree with me, but I think Geologist should reexamine their data. The day of Earth Quake Prediction is very near to us. The Earth’s Core is very heavy, made of radiactive heavy elements. In fact, it is so much like a planet within a planet, I named it after myself…Planet Martin Nix!

  • Steve Allen

    The measured annual variations in earth rotation due to weather have an amplitude of a millisecond, some 1000 times larger than the computed effect of the Chile earthquake. See the bottom plot at

  • PaulyG

    So, Martin. Where will the next big one be?

  • Brad Hallisey

    Doesn’t this assume you live in the Northern Hemisphere? I would guess the Southern Hemisphere’s day is equally longer. Since the origin of this story is Chille, which is in the Southern Hemisphere, the title is rather misleading.

    Don’t be such a Hemisphere bigot!

  • Kevin Gooding

    No, Brad, this is not a hemispheric issue. The key phrase is this: “the rate of the planet’s rotation determines the length of a day.” The speed of rotation would effect both Northern and Southern hemisphere in the same way.

  • PaulD

    Surely the northen hemisphere will spin at the same rate as the southern hemisphere, otherwise the world will unscrew itself.

  • JB

    The length of the day is determined by the time it takes for the Earth to make a full rotation. You can think of this as the amount of time between one sunrise to the next for any given location. While it is true that the northern hemisphere is currently experiencing winter, and the southern hemisphere is experiencing summer, BOTH the northern and southern hemispheres will experience a decrease in the length of a day because the entire earth is theoretically spinning faster. The southern hemisphere will experience a slightly shorter summer day, while the northern hemisphere will experience a slightly shorter winter day.

    Have a happy summer!

  • Brad Hallisey

    Ah, right.

    I guess I’m so excited with the lengthening days, I was thinking more about the effect the tilt has on the length of the day throughout the year and not the rate of rotation. That makes sense, thanks for the comments.

    My attempt and nerd humor == teh fail.

  • Kevin Gooding

    Brad, no worries.

  • Katharine

    Martin Nix forgot his meds.

  • Katharine

    Also, it’s called ‘plate tectonics’.

    Also, Martin Nix doesn’t know physics worth squat.

  • Sassy

    Does this mean I have to re-set my coffee maker? (snark)

  • Jesse

    Prayer, prayer, prayer…

  • Luigi

    that was a very interesting piece Martin Nix …..and it makes sense , I would like to see some physicists and mathemeticans tackle that hypothesis. Afterall if the displacement of water , can effect the Earths rotation , it’s seems [intuitively ] that any movement of the Earths core could do the same with the oblate sheroid which is the earth . I’m no scientist and when your woirds hit my minds eye , I attempt a picture of interactions between mass and it’s distribution and gravitation , and extrapolate that to affecting changes in shape as to the crust and mantle of the planet , which of course would cause effects in the movements involved in plate tectonics . I do not discount the other gentleman’s post on weather , but to a much lessor degree of effects , especially regarding tremblors .

  • Luigi

    …in addition , we can describe the movement in plate tectonics ei : direction of subduction , and the various locations and determine which plate is doing what , but again I ‘m not sure of whether the forces that drives this movement , is fully understood , the rotation of the Earth ? the gravitational effect of the moon ? the gravitational interaction of both ? The tremblors I believe are caused by the pressure built up between the tectonic plates , and when a weak part giveway , they slip inder or by one another causing the tremblor . If a particular cylce of gravitational interaction between the moon and earth /and /or its core can be described as a trigger and thus predicted , that would indeed be a great discovery .

    …just the thouights of a non-scientist , but I do have an open mind .

  • biologie.

    Crap! Darn mathematicians and uber scientists pulling a cloud cover over an otherwise sunshiny day. :) But I need my sunshine! Every microsecond of sunshine I can get is a good thing, imo.

  • Taru Zinyemba

    so all this mean that all the clocks have to be addjusted or we shall add a day or days to our calender i gues adding a day to the month of feb how is this

  • minetruly

    I’d just like to thank all you guys for not bring 2012 doomsdayers extrapolating from this and saying, “If an 8.8 Mw earthquake can shorten a day by a microsecond, then the events of 2012 can shorten the day by HOURS or even WEEKS!”

    … but maybe that’s because 2012 doomsdayers don’t read actual science sites like .

    A question from ignorance, though: Aren’t the days actually a different length at the north and south poles, depending on season? Like, inside the Arctic Circle, don’t they sometimes have the sun in the sky for months at a time? Does this shift mean that the north pole’s months-long days will ALSO be shortened by 1.26 microseconds, or will it be slightly more or less?

  • minetruly

    sorry, in the first sentence, “bring” should be “being.”

  • http://www.holodiscustechnical William H

    They make these claims after every earthquake. Were this so, the Earth would have stopped rotating by now or would be spinning like Jupiter. Consider this: there is no set point in space from which to measure such an acceleration or deceleration. Instruments are not quite accurate to measure such by the relative movements of stars or planets, so it is assumptions, like much of junk science today. Too, far less than 1% of the mass of the planet is concentrated in the crust, which is 10 to 30 miles in thickness versus ~7900 miles. A movement of the crust, while it makes seismic waves that can be measured around the globe, is not able to alter the structure of the planet. It’s unlikely that anything less than a large collision would alter its orbital characteristics. Yes, there is a moment, a torque if you will, involved in crustal movelments due to the distance from the centroid of the Earth, but it’s still like a bacterial movement trying to move an elephant. These claims make for good reading, but they are not solid geology.

  • Vvixen


  • BDZ

    I thought the earths rotation/orbit around the sun was a careful balance. Wouldnt billions of years of tectonic ativity, assuming some quakes ACTUALLY could change the speed of the earths rotation, eventually compound causing the earths orbit to change? If this were possible would the earth even exist? Has our orbit changed over the ages?

  • BDZ

    sorry William H read your post after mine lol…but yea i’m skeptical about this claim. I’m not a scientist.

  • Bongani Arthur

    It would be nice to be able to predict earth quakes….but at my 3rd year Geology class we were taught exactly what Luigi said “…caused by the pressure built up between the tectonic plates , and when a weak part giveway , they slip inder or by one another causing the tremblor.. “….it makes more sense, just like if you were to rub two rough rocks together. I do not discount the idea of the earth’s core moving around within the earth though. The earth’s plates are floating on magma isn’t it and the core is way way deep, so how does it bump against the fault line that is in the upper crust….well I am just a mining engineer and maybe some geologist/seismologists can enlighten us on that (Planet Martin Nix) hypothesis.

  • MCRumph

    But if the earth’s core were to move and wobble around, wouldn’t that change the magnetic poles or play havoc with the magnetic field that is generated by the core?

  • http://firefox su

    so, wow, everyone sounds so smart… well the earths core is not solid, however it is contained except for lava ect., change is eternal and the earth is in constant change not evolving but degrading, we evolve as we adapt… so enjoy it all while u can because soon all the water will displace and life will change again and there, go smoke one and relax…

  • http://firefox su

    i also think martin nix sounds like he has givin this some thought… magnetics are the next big discovery waiting in the wings for space ship launching and quiet travel

  • martin nix

    Nice to see some people take serious my Planet Martin Nix hypothesis of the earth’s core moving around influencing earthquakes. i bet the US Navy has some work on this, in that it would be useful to know which earthquake is where and when. Yep, a lot of work needs to be done on it, but if you look at the data between the location of the moon, and the location of major earthquakes you will see some correlations. Martin Nix

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