New Mexico Is Stretching, GPS Reveals

Velcroman1 writes "New Mexico's borders are gradually gaining girth, according to the Albuquerque Journal. It's not much, and it's not happening very fast — the state is getting about an inch wider every 40 years — but the state is unquestionably expanding, according to University of Colorado geophysicist Henry Berglund and his colleagues. Using a collection of 25 extra-precise GPS receivers planted across New Mexico and Colorado, Berglund determined that the cities of Albuquerque and Santa Fe are creeping away from each other. The rate of change seems ever so slow to the untrained ear, described as approximately 1.2 'nanostrains' per year."

Comments

Black Mesa

[bonch]

But the effect in continental interiors -- on states not near the edge of those plates -- was a new one, the scientists said. Whether an upwelling in the gooey mantle that lies beneath the crust or a sag in the plates themselves, what exactly drives the growth remains a mystery.

Probably those experiments over at Black Mesa. By the way, the portrayal of New Mexico in Half-Life always amused me, with the cartoonish Looney Tunes cliffs and plateaus. With the exception of the northern area of the state, it's mostly just weeds as far as the eye can see, littered with the occasional beer can. We have good Mexican food, though.

Re:Black Mesa

[PRMan]

Actually, I recently drove through New Mexico and was surprised by the green fields, grazing animals and tons of nice-looking farms/ranches along a long stretch of road. It was not what Looney Tunes said it would be (that was Arizona).

There go my plans

[rbowen]

So much for driving to California next summer. It'll be farther away by then.

Re:There go my plans

[R3d M3rcury]

Perhaps I'm taking this too literally...

I'm not sure New Mexico can get any wider--it's borders are set along latitude and longitude lines. So it's more likely that Albuquerque will eventually end up in Arizona and Santa Fe will end up in Texas.

Re:There go my plans

[Anonymous Coward]

I'm not sure New Mexico can get any wider--it's borders are set along latitude and longitude lines.

It's borders are not defined by the latitude and longitude lines, but by the markers set by the surveying team which attempted to follow the latitudes and longitudes. In pretty much every country, certainly all regions of North America, boundaries that were intended to follow specific latitudes or longitudes don't change as our ability to more accurately define these imaginary lines on the globe. Typically the act in Canada or the U.S. that defines the national, state/province or county borders as following specific lat. or long. lines also includes the phrase "as defined by" and the specific survey mission that defined the border using the technology then available.

So every border that is popularly defined by a latitude or longitude is rarely accurate as the technology was often quite crude compared to what we can do today.
Therefore, yes New Mexico can and is getting wider and Albuquerque and Santa Fe are going to remain part of N.M. as long as some kind of hispanic revolution doesn't occur. ;-)

The Obesity Epidemic

[Anonymous Coward]

...is so bad in the United States now, even the GROUND is getting fatter.

Re:The Obesity Epidemic

[rts008]

Why do you hate America?
High Fructose Corn Syrup!!! Where's the Beef? Supersize me!
Wahoooo!

Not News

[sunderland56]

Yeah, yeah, we know - America is getting fatter.

GPS Accuracy

[Proudrooster]

Fellow Slashdotters... this is a little off topic, but is there any way to get accuracy out of GPS? I can barely get plus/minus 12 feet of accuracy out of my GPS in the best conditions. How are they able to determine sub-inch accuracy? This sounds impossible, even with "25 extra-precise GPS receivers" as stated in the article. I just don't believe it is possible to measure to this level of accuracy with GPS. Someone please prove me wrong and school me how to build one with this accuracy for my autonomous lawn bot :)

Re:GPS Accuracy

[BitterOak]

They probably use techniques like differential GPS to increase their accuracy.

Re:GPS Accuracy

[__aaltlg1547]

You use 2- frequency GPS receivers that are inherently less noisy and more accurate than the cheap ones everybody uses for coarse navigation. Then you average the position data over long times.

The longer you average, the lower the uncertainty in the position.

Re:GPS Accuracy

[dido]

Differential GPS gets accuracy to up to 10 cm, which is just above 4 inches I think. It seems that it is possible to obtain even sub-millimeter accuracy from GPS, although I gather the techniques used aren't real-time, and as such unsuitable for mobile robotics. :( They work well enough for surveying though.

Re:GPS Accuracy

[oneblokeinoz]

The key thing is that this level of accuracy is not achieved in realtime.

The receivers would be recording more than the information contained in the GPS messages, they would be recording phase and signal strength data for all the satellites in the visible constellation.

Sophisticated post processing software would combine this information across multiple receivers, along with published satellite ephemeris data, to produce an accurate position solution.

Realtime positions cannot be that accurate due to affects like ionospheric refraction etc.

I used to work with a mobile system that recorded the GPS data along with inertial information (at 200Hz) that in realtime gave a solution that was usually accurate to within 30cm, and got to better than 10cm when combined with static ground station data in the post-processing step.

There are systems used in agriculture that are very accurate (10cm-ish) that use differential-GPS in realtime. The trick is your mobile unit has to be in constant communication with the differential ground station. Works ok for tractors, not so well for an aircraft 200-300km away. For differential-GPS to work well both units need to see the same satellites.

Re:GPS Accuracy

[NatasRevol]

They also use very large antennas (relative to commercial/handheld units).

The antenna's Henry is using are about 20" across and have some shielding to protect from signals reflected from the ground.

See:
http://facility.unavco.org/kb/questions/325/5%7B47%7D8%22+Stainless+Steel+All-thread+Mast+Overview

I know, because I work there.

Re:GPS Accuracy

[maroberts]

I was working for a company on differential GPS back in 1992 and we were obtaining precision of less than a centimetre for differential GPS even then, real time. Admittedly "real time" was only about 1 update every 5 seconds or so but that was good enough for surveying purposes. Also we were generating an atomic reference clock using GPS to correct the receiver oscillator. If the resulting time signal was good enough for radio astronomy at Jodrell Bank, I presume it was good enough for anyone.... We were using 68000 processors (later 68020) backed up by custom ASICs; Clock speeds and power have come a long way since then.

This is news?

[QuasiEvil]

Seriously? The entire Rio Grande Valley - which pretty much covers a north-south line right down the middle of the state - is a rift valley. The continent has been splitting and spreading here for millions of years. It's an interesting measurement, to be sure, and it's nice to have confirmation, but it shouldn't come as much of a surprise.

Bugs Bunney was a trickster....

[rts008]

You took a wrong turn in Albuquerque....