GPS To Monitor/Predict Seismic Stresses

webNazi points to this story at CNET, writing: "With over 250 GPS monitoring stations installed over the last ten years, the monitoring stations will provide continuous data--for 50 years or more--about otherwise imperceptible shifts in the Earth's crust. The network is so precise it can record as little as 0.04 inches of distortion of the ground or movement along a fault."

Cool, but what about my GPS

[squeegee-me]

I'm still looking for a GPS that will have that kind of accuracy. The Military has it, but they also have the access codes that change something like 10,000 times a second and map downfeeds to the units. I also know Farmers found a work arround that includes one stationary unit that ties into a computer to tell the other unit(s) that no you did not just move 10.342841 meters to the north, so don't turn the grain harvister yet. But what about me?

Details...

[RareHeintz]

The article was a little light on technical details. Does anyone know if they were using interferometric GPS or what? I know that was supposed to get down to ~2mm resolution...

OK,
- B
--

SuomiNet

[MarkMac]

Another closely related project (in fact I think they share GPS groundstation receivers with the Southern California geodetic folks) is SuomiNet

http://www.unidata.ucar.edu/suominet/ [ucar.edu]
http://www.unavco.ucar.edu/equipment/suominet/ [ucar.edu]

SuomiNet is a national network of GPS receivers, located primarily at universities, configured and managed to generate near real-time estimates of precipitable water vapor in the atmosphere, total electron content in the ionosphere, and other meteorological and geodetic information.

Example use of this data can be found at:
http://www.gst.ucar.edu/gpsrg/realtime.html [ucar.edu]

Neat stuff! Now if only the data from these fixed GPS sites were easily available via the web ...

im the only person with guts here

[mozkill]

i am going to ask a question.

how in the hell can a bunch of satellites measure within a fraction of an inch over the course of 50 years when we have enough trouble just making clocks with that similar magnitude of accuracy without using atomic mechanisms.

Re:Cool, but what about my GPS

[Yet Another Smith]

Well, you can get your own GPS which is capable of taking real-time differential corrections, but as a stand alone unit, you can't do better than about 5 meters with the C/A code (which is unencrypted) and about 1 meter with the P-Code (which is currently encrypted, to keep the 'Bad Guys'(tm) from being able to send remote controlled bombs into the White House). The DOD turned off their artificial degradation which left commercial handhelds doing no better than 100m, so you should be seeing 5-10m accuracy these days.

Part of the problem with stand-alone GPS recievers is that the variations in the delay caused by the ionosphere is enough to screw you up by a meter or two.

The way they do the super-high accuracy stuff is to have two GPS recievers, one on a known point, and the other as the 'rover' and they both measure the actual carrier wave of the signal. Back in the day (I was doing this while working on my masters in geophysics way back in 1995/96), this type of thing cost about $10-20k, and required software that ran about $30k to process. I think that's come down some, but its still a specialized thing, and probably pricy.