Proof plate tectonics is flawed?

Ok.. I was watching Megaquake japan when I came to a stunning realization.
In the episode it says that during the 9.0 quake in japan.. The earth was shifted 10 inches and it's rotation was slightly sped up thus shortening our day by a fraction of a second. This is when bells started ringing in my head.. If the no outside force was acting upon the earth how can it speed up it's rotation without violating the laws of conservation? I look forward to your responses.

As I'm weak on the conservation of energy, if not an outside force then what, an inside force? An expanding core?

reply to post by mb2591


The change in rotation is not caused by any force. It's caused by a redistribution of mass at the surface of the earth, which, due to the conservation of angular momentum, causes the earth's rotation to be affected. In effect, the same thing happens when a skater is spinning and outstretches their arms - their spinning slows down.

I was already to debate you on this but you went to a place I cannot follow

I know geology but not so much in this area so I look forward to what people have to say on this.

Great question

Originally posted by CLPrime
reply to post by mb2591

 

The change in rotation is not caused by any force. It's caused by a redistribution of mass at the surface of the earth, which, due to the conservation of angular momentum, causes the earth's rotation to be affected. In effect, the same thing happens when a skater is spinning and outstretches their arms - their spinning slows down.

So what your saying is that the earth got slightly smaller around?

Originally posted by TerryMcGuire
As I'm weak on the conservation of energy, if not an outside force then what, an inside force? An expanding core?

edit on 25-6-2011 by TerryMcGuire because: Typo

This is my question to haha if no outside force (ex another planets gravity or something) is acting upon the earth.. Where did it get it's energy to speed up

Hopefully this clears things up

Originally posted by CLPrime
reply to post by mb2591

 

The change in rotation is not caused by any force. It's caused by a redistribution of mass at the surface of the earth, which, due to the conservation of angular momentum, causes the earth's rotation to be affected. In effect, the same thing happens when a skater is spinning and outstretches their arms - their spinning slows down.

was just gonna post this, but beat me to it ... this explanation is right on.

reply to post by mb2591


Essentially, yes. The earthquake occurred on a megathrust (subduction) zone, which, when the redistribution of mass at the surface of the Earth is is all taken into account, led to an ever-so-slightly smaller amount of mass distribution near the equator. Since we typically measure the size of the Earth by its equatorial circumference, you could say the Earth got smaller. Mass didn't get lost anywhere, though, it just got redistributed.

Originally posted by mb2591
Ok.. I was watching Megaquake japan when I came to a stunning realization.
In the episode it says that during the 9.0 quake in japan.. The earth was shifted 10 inches and it's rotation was slightly sped up thus shortening our day by a fraction of a second. This is when bells started ringing in my head.. If the no outside force was acting upon the earth how can it speed up it's rotation without violating the laws of conservation? I look forward to your responses.

Okay: what happens when a spinning ice skater pulls her arms in? he/she speeds up( no additional force required).(Its all about"conservation of energy").

Originally posted by CLPrime
reply to post by mb2591

 

Essentially, yes. The earthquake occurred on a megathrust (subduction) zone, which, when the redistribution of mass at the surface of the Earth is is all taken into account, led to an ever-so-slightly smaller amount of mass distribution towards the equator. Since we typically measure the size of the Earth by its equatorial circumference, you could say the Earth got smaller. Mass didn't get lost anywhere, though, it just got redistributed.

Right ok.. So that would mean it got slightly denser aswell?

So if the earth has bulges and mass isn't evenly distributed. Then is it right to say earth has a new wobble to it? Also, where would the mass be at now and what would be the effects, if any?

Yes, that area got slightly denser, in a way.

No part of the planet is smooth or evenly spaced.

reply to post by mb2591


Not necessarily. It's also possible that mass was simply pulled away from the equator... in which case, the volume of the Earth didn't decrease, its shape just changed a little bit.
In the skater analogy, they pull their arms in to their body to speed up - which would correspond to a decrease in the Earth's volume. But, it's also possible that the skater lifts their outstretched arms up over their head. In this case, mass has still been moved away from the "equator", so the spinning still speeds up, but nothing has been "brought in", so the overall volume stays the same.

But, then, it's also possible that the volume did decrease...negligibly. Increasing the Earth's density by a ridiculously minuscule amount.

Or, the volume of the Earth might even have increased, slightly decreasing the density. So long as mass is moved away from the equator, the effect is the same.

reply to post by CLPrime


Yup.

Easy way to demonstrate this is to sit on an office chair and start spinning with arms and legs out, then pull them into your body, you will spin faster.

reply to post by chrismicha77


That would be responsible for this part:

The earth was shifted 10 inches

That's an additional axial tilt, also caused by the redistribution of mass.

Originally posted by CLPrime
reply to post by mb2591

 

Not necessarily. It's also possible that mass was simply pulled away from the equator... in which case, the volume of the Earth didn't decrease, its shape just changed a little bit.
In the skater analogy, they pull their arms in to their body to speed up - which would correspond to a decrease in the Earth's volume. But, it's also possible that the skater lifts their outstretched arms up over their head. In this case, mass has still been moved away from the "equator", so the spinning still speeds up, but nothing has been "brought in", so the overall volume stays the same.

But, then, it's also possible that the volume did decrease...negligibly. Increasing the Earth's density by a ridiculously minuscule amount.



Or, the volume of the Earth might even have increased, slightly decreasing the density. So long as mass is moved away from the equator, the effect is the same.

Ah thanks for clearing that up
Ok in this quake a plate rose 24 feet.. Do you know how the earth shifted around to cause this? (did somewhere sink 24 feet or what)

reply to post by mb2591


Are all forces , out there? Are there no forces in here?
If not, oh well. If so then what?

reply to post by mb2591


I'm not sure where a plate rose 24 ft, but here's what happened...

The Pacific Plate slides under the Honshu (Japanese) Plate, and friction causes the Honshu Plate to get dragged down with it. At some point, however, the stress on the Honshu plate becomes too great, and it gives way, releasing, in this case, energy equivalent to 9.32 million Megatons. This was pretty much energy built-up through the friction between the two plates. The release of the Honshu Plate did not require any sort of 'Newton's 3rd Law' reaction.

Sorry if this isn't what you're talking about... the only "rise" in the plate that I know to have occurred was due to the release of the Honshu Plate - which, of course, is what caused the tsunami.

reply to post by CLPrime

Or, the volume of the Earth might even have increased, slightly decreasing the density. So long as mass is moved away from the equator, the effect is the same.

And how might this be?

Originally posted by TerryMcGuire
reply to post by mb2591

 

Are all forces , out there? Are there no forces in here?
If not, oh well. If so then what?

Are you high?