Quake may have made Earth wobble

MrSelf · Post by **MrSelf** » Wed Dec 29, 2004 10:10 pm

LOS ANGELES, California (Reuters) -- The deadly Asian earthquake may have permanently accelerated the Earth's rotation, shortening days by a fraction of a second and caused the planet to wobble on its axis, U.S. scientists said Tuesday.

Richard Gross, a geophysicist with NASA's Jet Propulsion Laboratory in California, theorized that a shift of mass toward the Earth's center during the quake Sunday caused the planet to spin 3 microseconds, or millionths of a second, faster and to tilt about an inch on its axis.

When one huge tectonic plate beneath the Indian Ocean was forced below the edge of another "it had the effect of making the Earth more compact and spinning faster," Gross said.

Gross said changes predicted by his model probably are too minuscule to be detected by a global positioning satellite network that routinely measures changes in Earth's spin, but said the data may reveal a slight wobble.

The Earth's poles travel a circular path that normally varies by about 33 feet , so an added wobble of an inch is unlikely to cause long-term effects, he said.

"That continual motion is just used to changing," Gross said. "The rotation is not actually that precise. The Earth does slow down and change its rate of rotation."

When those tiny variations accumulate, planetary scientists must add a "leap second" to the end of a year, something that has not been done in many years, Gross said.

Scientists have long theorized that changes on the Earth's surface such as tide and groundwater shifts and weather could affect its spin but they have not had precise measurements to prove it, Caltech seismologist Hiroo Kanamori said.

"Even for a very large event, the effect is very small," Kanamori said. "It's very difficult to change the rotation rate substantially."

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Red Squirrel · Post by **Red Squirrel** » Thu Dec 30, 2004 5:21 pm

I heard stuff about this, quite impressive that it did global changes like that.

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MrSelf · Post by **MrSelf** » Thu Dec 30, 2004 5:25 pm

I'm not so sure about that wobble thing, it seems that we have had many earthquakes that powerful in the far past, and if that were true, the axis would wobble already, unless it wobbles then slowly levels back out...

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Red Squirrel · Post by **Red Squirrel** » Thu Dec 30, 2004 5:31 pm

Iti's probably what happends it stabelizes after a while and get's back in the correct rotation. But if shifted hard enough it could probably throw the Earth off the orbit but even that would take something like twice as powerful as the earth quake, probably.

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MrSelf · Post by **MrSelf** » Thu Dec 30, 2004 5:33 pm

The only problem is, theoretically, it should not level back out, that's not how the physics of the planet work. So I don't really know, something is wrong.

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Red Squirrel · Post by **Red Squirrel** » Thu Dec 30, 2004 7:24 pm

Yeah true, but I guess the gravity of the orbit is what makes it steady itself. There's a center of gravity and it just keeps pulling back and forth and slowly levels out, but not sure, since it does make sense that it would not level out, given the nature of space and newton's law.

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erolyn · Post by **erolyn** » Thu Dec 30, 2004 9:39 pm

From what I've heard, it's actually not that uncommon for the Earth's axis to shift a little bit from time to time.

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000 · Post by **000** » Fri Dec 31, 2004 1:05 am

Yes the earth does normally have a slight wobble. It does, do a search. The quake caused a break in the pattern or gave it a bit more of a wobble.

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Red Squirrel · Post by **Red Squirrel** » Fri Dec 31, 2004 2:15 am

I wonder what would happen if the earth's rotation would completely change, like the axis moving 90degrees or something. man would that mess things up.

Would take allot to cause that though...

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MrSelf · Post by **MrSelf** » Fri Dec 31, 2004 10:55 am

0 wrote: Yes the earth does normally have a slight wobble. It does, do a search. The quake caused a break in the pattern or gave it a bit more of a wobble.

I know the earth wobbles. Does it level back out, or are we constantly throughout time becoming more unstable? I mean, that makes sense as far as entropy, but not so much in observational history.

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Red Squirrel · Post by **Red Squirrel** » Fri Dec 31, 2004 12:07 pm

All I know is that this wobble caused a huge increase in temperature here today.

It's +6!!!!

That's just insane and I hightly doubt it's a coincidence since it's probably the first time it gets that hot here at this time of year. I did not figure a few feet closer to the sun could change things that much though... but this means it will woble farther and we'll get colder some time soon. That's if it's hapening the way I'm picturing it. Lot of factors that I'm probably not considering are involved as well.

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MrSelf · Post by **MrSelf** » Fri Dec 31, 2004 5:35 pm

crazy, but yeah it is uncharicteristically hot here today as well.

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