In New Zealand we use a special local coordinate system NZGD2000 that accounts for both tectonic drift and one-off Earthquake slip events.

The numerical coordinate values stay the same but their mapping to real world positions change over time. Hence the coordinate converter requires date as a parameter: https://www.geodesy.linz.govt.nz/concord/

https://www.linz.govt.nz/guidance/survey/earthquakes/kaikour...