Bureau of Continental Drift Corrections  ·  Sheet 1 of 1  ·  Geodetic corrections
Bureau of Continental Drift Corrections
Current epoch · ----

The ground moved. Your coordinates did not.

Nothing you own has been relocated. It is simply no longer where the paperwork says it is, and the paperwork was correct when it was written.

Every continent is in motion, at roughly the rate a fingernail grows. A coordinate is a statement about where something was on the day it was measured, on a reference frame that was pinned to a plate that has since carried it somewhere else. The Bureau issues corrections. It does not move anything back.

Benchmark, Australian plate · schematicDatum epoch 1994.0
A schematic survey benchmark: the crosshair marks where a plate-fixed datum says the point is, and the offset dot marks where a nominal 70 millimetres per year has since carried it
Where the datum says it is Where 70 mm a year has taken it
70 mmTravelled each year
-Accumulated since 1994
NNEDirection of travel
0Objects relocated
Correction notice

How far your coordinates have walked off since you wrote them down

Select the plate the measurement was taken on and the year it was taken. Rates are long-term averages from space geodesy and vary across a plate, so this is an order of magnitude rather than a survey.

No notice issued. The plate is moving regardless.
Motion rose

Which way each plate is taking its contents

Horizontal plate velocity · no-net-rotation frameArrow length · millimetres per year
A compass rose of plate motion: each plate drawn as an arrow in its direction of travel, with length proportional to its speed in millimetres per year
Schematic, and not to scale as a map: each arrow is drawn in the plate's approximate direction of travel, at a length proportional to its speed, in a no-net-rotation frame of the kind used by NNR-MORVEL56. A plate does not move as a rigid slab, and the figures below are averages of a motion that differs from one end of a continent to the other.
CodePlateCarrying, among other thingsRate
Case files

Corrections the Bureau did not have to invent

Australia · 1994 to 2020
1.8 m

A continent rewrites its own datum

Australia's coordinates were fixed to the plate at the start of 1994. The plate kept going, and by 2020 it had carried the country about 1.8 metres from where the datum said it was, which is a great deal when a tractor is steering itself. The replacement was gazetted in 2017 and its coordinates were propagated to the beginning of 2020: a datum deliberately placed where Australia was going to be, rather than where it was.

Japan · 11 March 2011
5.3 m

Two centuries of drift, in one earthquake

The Tohoku earthquake moved the coast of Honshu east, by 5.3 metres at the Oshika station in Miyagi. At the rate this coastline ordinarily travels, that is something like two hundred years of drift delivered at once. Survey control across a large part of the country stopped being correct in an afternoon, and had to be re-observed and recalculated, with the rest corrected using published parameters.

Iceland · annually
~2 cm

A country being taken in two directions

The North American and Eurasian plates pull apart across Iceland, and at Thingvellir the rift is written into the rock where you can walk through it. It is a zone rather than a seam, and the ground between the two plates does not behave as one rigid piece, which is the difficulty: a single national datum has to describe a country that is getting wider in the middle.

Standing guidance

Notes issued to holders of coordinates

A coordinate has a date A latitude and longitude on its own is an unfinished sentence: it says where, and declines to say in which frame, and at what date. A datum pinned to a plate holds its numbers still on purpose. A global frame does not, and under it the answer moves by centimetres a year, about seven of them in Australia.
Your phone disagrees with your map Satellite positioning reports a global frame at whatever epoch it was realised for. A plate-fixed national datum holds still by design. The gap between them is not an error in either; it is the distance the plate has travelled since the datum was pinned.
Precision arrived before it was wanted Plate motion was measured long before anybody minded it, back when positioning was accurate to ten metres and the drift disappeared into the error bars. Centimetre positioning in ordinary hands is what made it conspicuous, and made it somebody's job.
The correction is to the record The Bureau amends the number, never the ground. Requests to have the ground amended are acknowledged and filed.