Move a position between epochs (ITRF2020 plate motion)

Model: ITRF2020 plate motion model: v = ω × X plus the origin rate bias, X(t2) = X(t1) + v (t2 − t1); a site velocity replaces the model

Accuracy: About 0.2 mm/yr on stable plate interiors (the model's fit); rigid-plate velocities can be wrong by centimeters per year in deforming zones

When to use this: Use this to bring a position to the epoch you need it at. A coordinate in a modern reference frame is only meaningful with the date attached, because the ground it sits on is moving — 15 mm a year in Kansas, more than 50 on the Pacific plate — so a position observed in 2010 and one observed today are not the same number even for a mark that has not shifted an inch relative to its neighbours. Give the plate, or a site velocity from a nearby continuously operating station, which is better wherever one is available. It is the companion to changing frames: frames and epochs are separate steps and both are usually needed.

Limitations: It moves a position in time, not between frames — that is the ITRF or NAD 83 tool — and the two are easy to confuse because both report a shift in meters. The model is rigid-plate rotation, so it is only as good as that assumption: on a stable plate interior it fits to about 0.2 mm a year, but in a deforming zone it can be wrong by centimeters a year, and those zones are flagged from Bird's PB2002 orogens with the advice to use a site velocity instead. It also cannot know about anything episodic — an earthquake, subsidence, a landslide — which moves a mark without warning and leaves this answer confidently wrong. Epochs are accepted between 1980 and 2100; further out the linear velocity is extrapolation rather than model.

Worked example: Kansas on the North American plate, 2010 to 2026.7. Source: PROJ 9.3.0 given the Altamimi 2023 rotation pole and origin rate bias and left to do the cross product itself: it lands within 4 nanometres in latitude, 1.2 in longitude and 2.4 in height, and 14 mm away if the origin rate bias is omitted, so the check distinguishes that term. It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.

Review: Not yet independently reviewed by a geodesist.

Last verified: 2026-09-19, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.

Status: version 1.0.0, core 0.1.0. See this tool in the verification report.

Checked against: 22 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.

Sources

• ITRF2020 Plate Motion Model, Geophysical Research Letters 50, Altamimi, Z., Métivier, L., Rebischung, P., Collilieux, X., Chanard, K., and Barnéoud, J., American Geophysical Union, e2023GL106373. Table 1 (plate rotation poles) and Table 2 (origin rate bias).
• An updated digital model of plate boundaries, Geochemistry, Geophysics, Geosystems 4(3), Bird, P., American Geophysical Union, PB2002, 1027 (orogens as GeoJSON by Ahlenius, ODC-BY 1.0). PB2002_orogens: the 13 zones of distributed deformation.

Terms

AUST: Australian plate

The ITRF2020 plate motion model's code for the Australian tectonic plate. Source: ITRF2020 Plate Motion Model

EURA: Eurasian plate

The ITRF2020 plate motion model's code for the Eurasian tectonic plate. Source: ITRF2020 Plate Motion Model

GRS: Geodetic Reference System

An Earth ellipsoid defined by the IUGG. GRS 80 underlies NAD 83 and is almost identical to WGS 84. Source: Geodetic Reference System 1980

NOAM: North American plate

The ITRF2020 plate motion model's code for the North American tectonic plate. Source: ITRF2020 Plate Motion Model

NUBI: Nubian plate

The ITRF2020 plate motion model's code for the Nubian (African) tectonic plate. Source: ITRF2020 Plate Motion Model

PCFC: Pacific plate

The ITRF2020 plate motion model's code for the Pacific tectonic plate. Source: ITRF2020 Plate Motion Model

SOAM: South American plate

The ITRF2020 plate motion model's code for the South American tectonic plate. Source: ITRF2020 Plate Motion Model