https://sideshow.jpl.nasa.gov/post/links/KAIK.html
2016 Kaikōura earthquake: https://en.wikipedia.org/wiki/2016_Kaik%C5%8Dura_earthquake
That's insane when it usually moves 2cm per year at most.
> WGS 84 is a global standard tied to no one plate. In essence, it is fixed to Earth’s deep interior.
Those drift vectors are based on GPS, which the article also says relies on WGS 84z
For instance Australia's GDA2020 [1] is based on ITRF2014 at epoch 2020.0. It replaced GDA94 which was based on ITRF1992 at epoch 1994.0. The difference is around 1.8 metres
[0] https://en.m.wikipedia.org/wiki/International_Terrestrial_Re...
[1] https://www.ga.gov.au/scientific-topics/positioning-navigati...
What Happens to Google Maps When Tectonic Plates Move? https://news.ycombinator.com/item?id=22146454 (January 25, 2020 — 2 points, 0 comments)
What happens to Google Maps when tectonic plates move? https://news.ycombinator.com/item?id=22145303 (January 24, 2020 — 188 points, 53 comments)
What Happens to Google Maps When Tectonic Plates Move? https://news.ycombinator.com/item?id=12216474 (August 3, 2016 — 2 points, 0 comments)
You'll find many countries in there with a bit of history of their datums and how they arrived at their present state. It's a dry reading that can be fascinating at the same time.
I'm a surveyor by trade and you hit the nail on the head.
One of my favorite parts about this stuff is the history, and how we humans have tried to understand the shape of our world better and better. And then how we've attempted to make that shape conform to a flat map so we can measure on it better.
Fascinating stuff.
"we removed most of the gulf islands, part of BC, Washington, Oregon, and California" ...
If someone knows more on this, don't hesitate to share :-)
[1] https://blog.openstreetmap.org/2017/03/31/osm-plate-tectonic...
Edit: Oh, April Fools. Seemed doable.
edit: right? It seemed credible, I only noticed the date at the end. The part where they would hide the edit from history was incredibly shady though, and that's what made me look even closer. I would hope they would never do this, if they even could. Without this part, the post would not have looked like an April Fools, just an actually good idea.
In my relatively tectonically stable country there is a single coordinate system for the whole country.
I'd imagine you need to record distance to a local landmark or similar? And what happens when there are shifts that end up in roads split in two like in Turkey last year?
https://nationalpost.com/news/world/turkey-syria-earthquake-...
Or else, they'd just build fences, forbid anyone from living on the coast, and maintain this artificial continental boundary forever...?
Yeah, nah - the flora jumped the gap 150 years ago already . . .
https://www.independent.com/2011/01/15/how-eucalyptus-came-c...
It's a interesting setting to explore in fiction, but has no chance of becoming reality.
⸻
1. When I think back to that car, it’s amazing what a piece of junk it was. On the other hand, it was a convertible, so a lot of fun although my wife considered it a deathtrap.
About 10 years ago, I did a lot of canyoning/bushwalking in the Blue Mountains just outside of Sydney Australia. I’d have my Garmin GPSMAP switched on for the entire journey including the car trip. For the 20+ journeys, there would be overlapping paths where I was driving the highway through the mountains. Except none of the paths overlap. They were all smooth paths which matched the curvature of the road, but each one had a different offset, typically around 2–5 metres away from the map data. (The median of these 20+ paths was highly consistent with the map data.)
> Because SA affects every GPS receiver in a given area almost equally, a fixed station with an accurately known position can measure the SA error values and transmit them to the local GPS receivers so they may correct their position fixes. This is called Differential GPS or DGPS.
https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_...
Important life skills
It’s not only the sideways movement of plates that causes a shift.
WGS 84 and other reference systems work with an underlying ellipsoid reference model. This ellipsoid is chosen to approximate the earth surface but it’s a simple shape and as such can’t account well for things like mountains and other irregularities in the shape of the earth.
Not only does that mean that your position on a mountain is less accurate, it also means that it becomes less accurate over time due to mountains growing.
These of course are tiny numbers so compared to a few cm shift of the plates it is nothing.
Another fun fact is that the ellipsoid also grows more inaccurate over time due to the earth rotating around a fixed axis.
The rotational force slowly causes the earth to flatten at the top and bottom (where the poles are) and to widen in the middle.
This too I assume is negligible
Speaking of ellipsoid, today I think it is measured via satellite. But in the past things had to be done by hand and were more local in nature. There’s a lot of history here as well since mapping has always been a very important task for governments.
So today in a lot of places a lot of data is still based on systems other than wgs84. Either because it’s historical data (e.g. property boundaries before gps was invented), or because they use a more localized reference system including a more localized ellipsoid that better matches specific country or state needs.
Perhaps one day we will use a big world wide look up table instead of a mathematical representation of the earth shape.
What I did at university was to compare a Germany-wide lookup grid with the mathematical approach of a Germany-wide reference system.
This lookup grid was created by a state agency and was more accurate because it could include more localized reference systems. In technical terms think of this as a pre calculation where each state can choose its most accurate method and then the results are put together into a country wide lookup table.
Last fun fact: The result of this comparison showed that the difference of a German-wide reference system compared to this collection of state-wide reference systems is up to four meters.
Edit: removed word inaccuracy, added difference. It’s all relative. What it mostly shows is that when working with geo data you need to know what source and what target reference systems to use. Otherwise things break
Some related problems are the planet’s location in orbit / the solar system’s location relative to the entire universe and how landscape changes over time (trees/towns/mountains/rivers appearing and disappearing).
On another related note, it’s worth noting that the ability to pause time is a universe-ending super weapon. Even if it worked like you intended, you wouldn’t be able to use any senses or breathe without moving.
Similarly, super speed would cause every human movement to have deadly force. You would go insane from the relatively slow action of everything operating at standard speed. TV might be hours per frame instead of frames per second, with incomprehensible audio to match.
In the age of OSINT: not smart.
Google needs to be dealing with it constantly, you'd be able to observe more errors on Google maps, ie. look at Google directions and how often mistakes are made, if it wasn't updated monthly? I'd guess yearly is not enough.
Most of this article seems to be about other issues.
Which means yo can model what the coordinates should be after some previous survey and go check them.
Pretty cool!
