http://www.msnbc.msn.com/id/35662192/ns/technology_and_science-space/?GT1=43001

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http://www.msnbc.msn.com/id/35662192/ns/technology_and_science-space/?GT1=43001

Maybe the earth had had enough of Global Warming and decided to do something about It. :D

MSN wrote:

The computer model used by Gross and his colleagues to determine the effects of the Chile earthquake effect also found that it should have moved Earth's figure axis by about 3 inches (8 centimeters or 2.7 milliarcseconds).

If an 8.8 moved the axis by 3", Then what did the 9.5 in 1960 do?

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

If an 8.8 moved the axis by 3", Then what did the 9.5 in 1960 do?

Right, or the 9.2 Alaskan quake in 1964?


Martin

If an 8.8 moved the axis by 3", Then what did the 9.5 in 1960 do?

Right, or the 9.2 Alaskan quake in 1964?


Martin

Probably not much as It is too close to worlds axis and so not enough leverage.

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

shortened the length of an Earth day by 1.26 microseconds

I barely have enough time to get everything done as it is... this certainly won't help.

If an 8.8 moved the axis by 3", Then what did the 9.5 in 1960 do?

Right, or the 9.2 Alaskan quake in 1964?


Martin

Probably not much as It is too close to worlds axis and so not enough leverage.

Well...I thought the article said the Chilean quake had more impact than the larger magnitude quake on the equator because it was closer to the axis. The Alaskan quake (which I remember seeing the news of on b&w tv as a youngster) occurred along Alaska's southern coastline, not that far north (latitude wise).

Either way, the science would be interesting to see.

Martin
edited...

shortened the length of an Earth day by 1.26 microseconds

I barely have enough time to get everything done as it is... this certainly won't help.

You'll never notice that amount of time lost per day, As It's a bit over a millionth of a second.

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

If an 8.8 moved the axis by 3", Then what did the 9.5 in 1960 do?

Right, or the 9.2 Alaskan quake in 1964?


Martin

Probably not much as It is too close to worlds axis and so not enough leverage.

Well...I thought the article said the Chilean quake had more impact than the larger magnitude quake on the equator because it was closer to the axis. The Alaskan quake (which I remember seeing the news of on b&w tv as a youngster) occurred along Alaska's southern coastline, not that far north (latitude wise).

Either way, the science would be interesting to see.

Martin
edited...

I think that what is most significant is the distance from a symmetry element - in the case of the Earth, approximately an oblate spheroid, the equator (a mirror plane) and the poles (rotational symmetry.)

The most significant redistribution of mass would be vertical - this would have no effect at the poles and only move the figure axis from side to side at the equator.

At mid-latitudes, though, that redistribution would change the tilt of the figure axis which would (I suspect) cause a more noticeable movement of its points of emergence.

If an 8.8 moved the axis by 3"...

That's quite a headache for GPS!...

Or does it get automatically readjusted from known reference points?...

Keep searchin',
Martin

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See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

If an 8.8 moved the axis by 3"...

That's quite a headache for GPS!...

Or does it get automatically readjusted from known reference points?...

Keep searchin',
Martin

I wouldn't worry about GPS, As It can't get down to 3" I've read...

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

I seem to recall that GPS calculates positions relative to the satellites. These rotate about the centre of gravity of the earth, so the whole surface, and the cloud of satellites, should have just moved over, and all the calculated positions will remain valid for the earth-borne user.

By the way, using multiple recievers with long term obervations and corrections, GPS positions can be accurate to a millimeter or less these days.

I guess things did shift relative to the Gallifreyan Pan-Galactic Grid, so the next inbound TARDIS may be 3 inches out when it re-materializes.

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I seem to recall that GPS calculates positions relative to the satellites. These rotate about the centre of gravity of the earth, so the whole surface, and the cloud of satellites, should have just moved over, and all the calculated positions will remain valid for the earth-borne user.

That's the whole point. The earth has shifted it's rotation. All satellites are now displaced along their orbits by that shift relative to a point on the newly shifted earth.

By the way, using multiple recievers with long term obervations and corrections, GPS positions can be accurate to a millimeter or less these days.

I guess things did shift relative to the Gallifreyan Pan-Galactic Grid, so the next inbound TARDIS may be 3 inches out when it re-materializes.

And ICBMs and cruise missiles, passenger airliners through to recreational boats, and anything else that now rely on GPS positioning.


There's many a foolish yachtie blindly plotting their course by GPS only to find they suffer flat batteries at some critical moment, or that a sand bar or worse has shifted where the channel 'should be'...


Keep searchin',
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

I seem to recall that GPS calculates positions relative to the satellites. These rotate about the centre of gravity of the earth, so the whole surface, and the cloud of satellites, should have just moved over, and all the calculated positions will remain valid for the earth-borne user.

That's the whole point. The earth has shifted it's rotation. All satellites are now displaced along their orbits by that shift relative to a point on the newly shifted earth.

By the way, using multiple receivers with long term observations and corrections, GPS positions can be accurate to a millimeter or less these days.

I guess things did shift relative to the Gallifreyan Pan-Galactic Grid, so the next inbound TARDIS may be 3 inches out when it re-materializes.

And ICBMs and cruise missiles, passenger airliners through to recreational boats, and anything else that now rely on GPS positioning.


There's many a foolish yachtie blindly plotting their course by GPS only to find they suffer flat batteries at some critical moment, or that a sand bar or worse has shifted where the channel 'should be'...


Keep searchin',
Martin

Well the US Militaries GPS is more accurate than Civilian and It's kept that way to keep our Enemies from being as accurate.

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

I seem to recall that GPS calculates positions relative to the satellites. These rotate about the centre of gravity of the earth, so the whole surface, and the cloud of satellites, should have just moved over, and all the calculated positions will remain valid for the earth-borne user.

That's the whole point. The earth has shifted it's rotation. All satellites are now displaced along their orbits by that shift relative to a point on the newly shifted earth.

No, the point is the satellites shifted too. The earth is always moving (around the sun, with the sun around the galactic centre of gravity, etc) and the satellites always go with them.

A much bigger problem, as Scarecrow's link points out, is when features shift relative to the surrounding items.

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I went sailing yesterday and tried it out. GPS still works fine. (Though mine is a lower end unit that has accuracy only +/- 20m, there may be issues if you want better accuracy than that.)

I think that things like changes in atmospheric density (high and low pressure areas, for example) would have as much an effect but is still managable.

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Pure mathematics is, in its way, the poetry of logical ideas.

Albert Einstein

I went sailing yesterday and tried it out. GPS still works fine. (Though mine is a lower end unit that has accuracy only +/- 20m, there may be issues if you want better accuracy than that.)

I think that things like changes in atmospheric density (high and low pressure areas, for example) would have as much an effect but is still managable.

Um, I think things like atmosphere and things like that such as water vapor have nothing to do with GPS(Global Positioning System).

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

I went sailing yesterday and tried it out. GPS still works fine. (Though mine is a lower end unit that has accuracy only +/- 20m, there may be issues if you want better accuracy than that.)

I think that things like changes in atmospheric density (high and low pressure areas, for example) would have as much an effect but is still managable.

Um, I think things like atmosphere and things like that such as water vapor have nothing to do with GPS(Global Positioning System).

Actually, they do. The speed of light (and radio waves) varies with the density of the medium they are traveling through. Denser atmosphere, moisture, etc slow them down. Not much, but enough to have a noticable effect that has to be compensated for.

Which makes me think that any issues as a result of the shift in the COG of the earth or a slight change in its position, bulge, etc should be easy to compensate for with minor changes to the computer code.

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Pure mathematics is, in its way, the poetry of logical ideas.

Albert Einstein

I went sailing yesterday and tried it out. GPS still works fine. (Though mine is a lower end unit that has accuracy only +/- 20m, there may be issues if you want better accuracy than that.)

I think that things like changes in atmospheric density (high and low pressure areas, for example) would have as much an effect but is still managable.

Um, I think things like atmosphere and things like that such as water vapor have nothing to do with GPS(Global Positioning System).

Actually, they do. The speed of light (and radio waves) varies with the density of the medium they are traveling through. Denser atmosphere, moisture, etc slow them down. Not much, but enough to have a noticable effect that has to be compensated for.

Which makes me think that any issues as a result of the shift in the COG of the earth or a slight change in its position, bulge, etc should be easy to compensate for with minor changes to the computer code.

Um, Thats speed, GPS measures Your Position on the Earth, Not Your Speed Mac. As Density is not mentioned even once in the GPS Wiki.

GPS Wiki wrote:

Basic concept of GPS

A GPS receiver calculates its position by precisely timing the signals sent by the GPS satellites high above the Earth. Each satellite continually transmits messages which include

* the time the message was transmitted
* precise orbital information (the ephemeris)
* the general system health and rough orbits of all GPS satellites (the almanac).

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

Which just goes to show you how much you should trust Wikis in general.

The effect Ms. KenzieB describes will effect the delay between the signal leaving the satellite and arriving the receiver, and this "time of flight" is a basic part of the position calculation. That's why every GPS receiver needs a very accurate clock, and also why that clock is constantly updated by a portion of the signal from the satellite constellation.

Water vapour in the air is the major variable producing position errors. Air density has some effect, but it is smaller. The higher accuracy differential GPS works by having a receiver at a known location, that constantly calculates the difference between its real location and the current GPS derived location. This is then broadcast as a short range signal, so other GPS signals in the area can be told, for example, that every local GPS right now is reading 4 feet to the East. They use a short range signal because the water vapour and air density can change over larger distances, producing different errors.

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