Anyone experiencing GPS errors since tsunami?

**wizardPC** · 01-01-2005, 11:04 PM

I was just wondering if anyone, particularly you guys in Asia and Australia, has experienced errors in accuracy since the tectonic plate shift that caused the tsunami. Apparently, some places have been shifted by 100 feet or more, and the earth's rotation was slightly affected.

Since the GPS satellites are in synchronous orbit, it stands to reason that the postions of these satellites with respect to the ground have shifted somewhat. I didn't notice any changes this weekend while driving around, but I don't know about you guys that are closer to ground zero.

**rando** · 01-02-2005, 12:49 AM

The reports I saw 'suggested' that the earths rotation might have been impacted by 1uS/year. I believe that's something around 1/55th inch/year -- probably well within the accuracy of the satellite orbits in the first place. Land shifts should have no impact on GPS solutions though they might make current maps a bit innacurate.

**grepzen** · 01-02-2005, 07:10 AM

... but nothing you'll miss a turn over. --given that the unit in your car is accurate to 2-3meters or so.

**DaRacerz** · 01-02-2005, 10:30 PM

is it 1uS/year? Cause I read somewhere else (I don't remember of the source) that formentioned that each day is 1mS shorter. But in either case, this has to be well within the range of adjustability for the satelites.

Though, the titonic plate shift is significant. Also heard the 100ft (30 meter) figure put out. Thats gotta be catastrophic to the GPS mapping infrastructure. Just the question is what countries that have been mapped are effected.

**rushnrockt** · 01-03-2005, 05:24 AM

Originally Posted by DaRacerz

is it 1uS/year? Cause I read somewhere else (I don't remember of the source) that formentioned that each day is 1mS shorter. But in either case, this has to be well within the range of adjustability for the satelites.

Though, the titonic plate shift is significant. Also heard the 100ft (30 meter) figure put out. Thats gotta be catastrophic to the GPS mapping infrastructure. Just the question is what countries that have been mapped are effected.

The numbers are about a single plate DROP, so that does not affect the surface area of earth quite as radically as you might think in the first place. Then consider 100 feet in relation to the circumference of Earth, something like 23k miles, and it is becoming completely insignificant.
And the actual number quoted was in fact 1uS/year and most commonly mentioned number for plate drop is 30 feet, not 100. So gps will do just fine.

**serendipity** · 01-17-2005, 02:26 PM

Also, GPS satellites are not in a synchronous orbit. They constantly circle the earth, so at any given time, a handful of them will be within "view" of any point on earth.

**trillion** · 01-19-2005, 02:35 AM

I read that IntelSat recently lost a satellite into space due to an "anomaly". Not very often you read about that, or perhaps it just doesnt make its way into mainstream geek news too often.

**0l33l** · 01-19-2005, 02:38 AM

By my knowledge of tectonic plates, that earthquake should have just affected that plate. Its not like any of the other plates moved.

**CraZyItalian041** · 01-19-2005, 02:39 AM

Those tsinamis did shift alot of plates and also caused alot of subduction zones in the area where the quake was. The fact that rotation was affected and that some places shifted may have cause the earths orbit to move a tiny bit which in exchange might have possibly thrown off the satellite. Another factor may be the fact that the earths rotation speed was increased by a few milliseconds. This may have cause a minor change in the earths electromagnetic field polarity. But wow that was a tangent... My fault but yeah It may have affected it a little bit... But like the others said probably nothing large scale.