# Japanese Earthquake and the Earth's Axis

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quotationsposted 7 years ago

I have heard on the news that the earthquake was so powerful that it changed the earth's rotation and axis by a small degree. I heard a similar story about the Indonesian earthquake.

Does anyone know:

1. what is the cumulative effect of both earthquakes on the length of the day and the earth's axis tilt

2. will the change have any effect on climate? I am thinking that even a small shift in the axis would have a noticeable effect on the polar regions.

Anyone know?

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Baileybearposted 7 years agoin reply to this

some reports said our day was shortened by a fraction of a second.  Axis moved by around 25 cm & parts Japan's coast moved closer to US by 2.4 m (8 ft)

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Rafiniposted 7 years agoin reply to this

I would really like to know how they determine these things.

I heard the day was shortened by 4 minutes (one day or every day?  they didn't say)
The Axis - I don't remember exactly, but I think it was 4 cm or inches.
And, I heard Japan moved West by 13 feet.  (not just the coast, the entire country!)

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logic,commonsenseposted 7 years agoin reply to this

GPS is how they determined how far Japan moved.

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Rafiniposted 7 years agoin reply to this

oh yeah!  I did hear that.  Kinda cool in an exciting yet scary way....

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superwagsposted 7 years ago

It happens because the earth's crust has been forced up by a few feet over a vast area as the Pacific plate has slipped under the Japanese one. My understanding is that it throws out the speed of the earth's spin from the norm because it shifts the distribtion of the Earth's mass. i.e. the mass is further from the centre of the globe.

I'm aware I haven't done a very good job of explaining that, for a former earth-sciences student!

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superwagsposted 7 years ago

Oh, and incidentally, they measure it using super accurate atomic clocks. It wont be enough for us to notice it!

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melporposted 7 years ago

It just increased the earth's rotation speed by 1 microsecond or 1/1000000 of a second. The the length of the day was decreased by 1/1000000 of a second. I do not think anyone will notice that. This effect will not change anything. The axis was shifted by about a degree and then resets itself because the moon is responsible for keeping the earth's axis at the 23 degrees tilt. The moon also stabilizes the earth's axis so it pretty much keeps it in its current orientation. These effects are extremely small to cause any significant change in our weather system

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superwagsposted 7 years ago

As usual, the BBC has managed to answer this in a more succinct way than me!

http://www.bbc.co.uk/news/science-environment-12732335

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