[perotid]

FWIW, global drift vectors by NASA: https://sideshow.jpl.nasa.gov/post/series.html

[teruakohatu]

If you want to see an interesting one in my country:

https://sideshow.jpl.nasa.gov/post/links/KAIK.html

2016 Kaikōura earthquake: https://en.wikipedia.org/wiki/2016_Kaik%C5%8Dura_earthquake

[77pt77]

There are deltas there of over 70cm.

That's insane when it usually moves 2cm per year at most.

[teruakohatu]

It was insane. There was a massive die off of marine life. One movement they were happily swimming in the sea or crawling on the sand, next minute they were above the sea.

[dtgriscom]

... what's the origin, when the entire surface of the Earth is sliding around?

[tkcranny]

From the article:

> 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

[saalweachter]

And on fixed surveying markers around the globe.

You'll see them hither and yon, but my favorite is the miniature Washington Monument buried next to the real one.

[smolder]

For anyone curious about the buried mini-monument: https://www.atlasobscura.com/places/washington-mini-monument

[hank1931]

Thank you for turning me on to Atlas Obscura! I downloaded the app, and have already marked several places I want to visit, and others that I've been to. Looking forward to working with it more!

I happened to have been in Thailand recently, and came across these statues holding up traffic lights. I found it fascinating that a city council would devote resources to something like this. I'm looking forward to seeing other treasures that Atlas Obscura has.

https://www.atlasobscura.com/places/krabi-traffic-lights

[SketchySeaBeast]

That's gonna be a trip for archaeologists in a few thousand years.

[moffkalast]

> it is fixed to Earth’s deep interior

Which is molten and also not static?

[appletrotter]

The core of the earth is solid no?

[nobodyknowin]

It's based on a center of mass point of the earth.

The system is an example of an "ECEF" or Earth Centered Earth Fixed system.

Good writeup here -

https://en.m.wikipedia.org/wiki/Earth-centered,_Earth-fixed_...

Edit - fixed center statement.

[moffkalast]

I still don't quite get it. So the center is the barycenter of the planet, but that only gives you the point, not the axes.

The Z axis seems the most clearly defined as it's just aligned to the planet's rotation and the XY plane could be defined as just halving that, but the the rotation of the XY plane doesn't seem to be well defined. The article seems to fix it to the first meridian which is a land reference and subject to drift, so it would be inaccurate. Or there'd be some reference point in the south atlantic where the drift is zero and the rest is relative to it?

Further along this line of discussion, it's always been immensely puzzling to me how sun-relative solar system localization systems handle this sort of thing, since while it's possible to locate the sun and a few stars to track your absolute rotation and one translational axis, where the hell do they get the other two? One reference might be Earth signals I suppose, and possibly Jupiter? But they are all coplanar so the Z axis resolution from triangulation must be complete crap.

[NooneAtAll3]

according to hairy banana theorem, at least one surface point won't be sliding sideways