# Can an earthquake shift the Earth's axis?

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| 18:11 UK time, Monday, 14 March 2011

d ~ 187'814'400 km: day 73

The short answer to this is yes. But the effects of such a shift are tiny. The Earth's tilt and rotational spin on its axis as it travels around the Sun causes our seasons. The earthquake in Japan moved the axis of rotation by around 16 cm. That might sound like a lot, but it's small compared to the size of the Earth. 1 degree change to the tilt of the axis of the Earth would mean moving it by around 110 km.

But the quake's interference with our axis doesn't stop there. The Japanese landmass was moved around by as much as 4m. This redistribution of mass on the surface changes our moment of inertia. In order to conserve angular momentum, the changes in inertia are compensated by changes in the rate of rotation of the Earth about the axis. After the earthquake it's quite possible that our days will be 1.8 millionths of a second shorter because of this shifting.

We can see differences in the average length of the day due to other changes in the Earth and atmosphere. The plots below show that there is a significant seasonal variation, with the day length (speed of rotation) being shortest (fastest) during the boreal summer. This happens because the northern hemisphere winds slow down in the summer and the momentum they lose - half the momentum of the atmosphere - is transferred to the Earth. This increase in momentum makes the Earth spin faster and our days become slightly shorter by 1-2 milliseconds.

So while the changes brought to our planet by the earthquake are unique and collosal enough to affect the Earth; they aren't big enough that we will notice them any more than we notice the milliseconds we lose each summer.

• #### Comment number 1.

Hi Bethan - As a layperson I am confused by your explanation of the effect of "the northern hemisphere winds slow down in the winter " and appearing to imply that this speeds up the rotation. This should mean shorter winter days, not summer? You end with "milliseconds we lose in winter" while I might expect a gain of microseconds?
Regards..Miaren

• #### Comment number 2.

Erm get the point of winds slower, earth rotation faster, daylength shorter. But don't get from your text whether this happens in winter or summer as it says both in different places. Thx

• #### Comment number 3.

Fair comments - and good eagle eyes! I've updated the blog to be clearer. We definately spin fastest in boreal summer as the NH jet streams slow down and the atmosphere loses half it's angular momentum.

We also lost a tiny chink of our day following the Chilean earthquake last year and the Sumatran earthquake in 2004: https://www.nasa.gov/topics/earth/features/earth-20100301.html

• #### Comment number 4.

Hi Bethan,

What is the cumulative effect of the Sumatra, Chilean, and Japanese earthquakes as all three were reported to change the Earth’s axis of rotation and the spin?

I think this would be a great add on here as this would help to determine if cumulative effect is additive or some of the shifts canceled each other out. This might imply that the Earth is in some way self correcting. Please let us know. I didn't see from my search this angle covered.

• #### Comment number 5.

The reason I ask this is that some of the earhquakes ocurred in the direction of the Earth's rotation and some act against the Earth's rotation.

The Chilean and Sumatra quakes are subduction zones that are in the direction of earths rotation while the Japanese quake was in the direction against Earth's rotation.

What I mean is the slip of the plate under the other occurs during the Sun's Rise versious a Plate slip that occurs during the Sun's setting. Maybe this does not matter at all but would like to know?

• #### Comment number 6.

Sorry misspoke in last post. Last line should read:

What I mean is the slip of the plate under the other occurs in the direction of the Sun's Rising versus a Plate slip that occurs in the direction of the Sun's setting. Maybe this does not matter at all but would like to know?

• #### Comment number 7.

This has been talked about. It so happens the moon is leaving us.

• #### Comment number 8.

I am feeling sudden change in temperature going higher since 2-3 days in my area, It feels like what I normally feel in month of may.

Would it be a more axis shift than actually reported..?? Or something else?

• #### Comment number 9.

Good questions!

@adnan: I think it's unlikely that the axis has shifted dramatically and caused an increase in local temperatures. Temperatures can fluctuate quite a lot and still be very much normal, even though they feel unusual for the time of year. I would say it's also pretty unlikely that the change in tilt is greater than that reported, but one way you could try check this for yourself is to go out and see if Polaris is still directly north all through the night...

@trekrod: That is a very interesting question indeed, and I'm sorry to say that I don't know enough about the detailed calculations to give you a satisfactory answer. Try the National Institute of Geophysics and Volcanology in Italy, who reportedly made the initial calculations. And let me know what they tell you!

• #### Comment number 10.

The quake has got everyone talking about earth shifting and shorter days but is there a natural force that can shift our axis and shorten our day in a way that we can see and feel, obviously without destroying earth?

• #### Comment number 11.

Trekrod I like your line of reasoning... " I think this would be a great add on here as this would help to determine if cumulative effect is additive or some of the shifts canceled each other out. This might imply that the Earth is in some way self correcting."

Is, or Does the Earth try to resolve its changes in angular momentum by a variety of method's via slowing / speeding up (which may or may not include slight changes to its radius), or even change its surface mass arrangement (earth quakes) to maintain a current momentum.
Can we though ask another question relating to causes, that is the moon moving away from the Earth, which it does and has been doing for some time by estimates of 1.5 " / year, which implies as many have noted the Earth and Moon must have been REALLY close to each other a few thousand years ago, but, nevertheless as the moon moves away, it lessons the slowing down of earths rotation, yet also Earths mass tends to contract into a slightly smaller sphere ( tidal forces ), which means the Earth has two possible paths, contract and speed up which tends to throw mass back out and nullify any measurement, or geological changes ( earthquakes ) to find a balance between all forces involved ....
thanks, etreed

• #### Comment number 12.

The statement, "The Earth's tilt and rotational spin on its axis as it travels around the Sun causes our seasons.", made in the article is incorrect. The spin on its axis results in the daily cycle. The travel of the Earth in its orbit around the Sun (and the tilt of its axis relative to the orbital plane) results in the seasons.

• #### Comment number 13.

Hi Bethan, I have been thinking of this for a very long time and with Google found
You. I have thought about the cumulative effects of the quakes and volcanoes on
the
Earths orbit/axis etc. We have had at least 3 about 1000 days apart give or take just
You mention something about 110km effect from the last quake. What is the
cumulative
Effect? I know that even a 20 mile fluctuation in the jetstream can alter the
weather
And bring spring/summer wind temps weeks earlier then the short recorded
normal.
Is your 110km figure based on one day or on a year? I would like your opinion
As to these major quakes, volcanic eruptions have a more cumulative effect
On climate change {which climate better be doing } then anything man could ever do.
Imagine the uproar if mankind caused the earth to wobble on its axis by 110km.
This information and free exchange of ideas will eventually shed light on the
Fraud of global warming or manmade climate change.

Paul

• #### Comment number 14.

bethan harris is wrong, the effect in the uk will be hotter seasons,if you look
at where the sun is now,it should be end of june early july,
she has been told to say that as to not cause concern, they seem to think we
are like lambs unable to think or act in our own interest if they give us the facts we can plan for the future i e plant diferent crops in the future, save water if the climate is hotter
we are not children.
yours william

• #### Comment number 15.

This comment was removed because the moderators found it broke the house rules. Explain.

• #### Comment number 16.

Good morning everyone it's currently Just not hit 5am Mountain time where I am located in Colorado,It's bright as day outside as if it was noon already here..The sun is coming up from the far north/northeast corner of the sky..

So here's some more knowledge on this..

I have done alot of research working for a privately owned astrophysics team. If noone understand's what's truly been going on for quite a while
This is new leak in the government that they do not wish for you to hear,Some may say.
Back in 2002 We all learned about a new shuttle that was about 4 times the size of the one's we currently have in out hangers. But it was never releaved to where the location of this shuttle had been put.,They had said they were going to use this for future missions to other planets. So here we are saying goodbye to the Space progam,But in all reality if you would pay attention to the news more often instead of many other things, And if you studied the Earth as I do, You would know that they are actually trying to find a way to save everyone from what is about to happen in the near future,As you all know about a comet and astroid they have claimed to not be in our heading but actually we are in it's heading and there's nothing noone can do nor nothing noone can say that will change anything. So this is the final mission to space ,Due to the end of the world coming from the astroid and comet coming our way,As you also were aware that a planet does not just pop up out of no where we've been to this other planet you can look up the new planet that is actually our brightest star out there as well. So God Bless and God speed to everyone..

https://www.nasa.gov/home/index.html
Related report...

• #### Comment number 17.

I am curious about your current views on the change in the axis. I live in the US, and there is significant changes in the weather this winter in respect to past years. For example, yesterday, January 31, 2012, most of the United States was blanketed with temperatures at or above 50°F. Many states and cities have recorded daily record high temperatures throughout the course of the winter. Conversely, areas north, such as Alaska, are recording some of the coldest temperatures on record.

( https://yfrog.com/oboxmbp ) NOAA weather map of US showing temperatures.

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