Crustal Deformation Correction Parameters

Japan sits on four tectonic plates and its ground moves by several centimetres a year, while official map and survey coordinates are fixed to a past reference date. High-precision satellite positions, such as those from the QZSS (Michibiki) centimetre-level augmentation service CLAS or precise point positioning (PPP), therefore drift away from maps and survey control points over time. The Geospatial Information Authority of Japan (GSI) publishes crustal deformation correction parameters to reconcile the two.

The parameters are computed from the daily coordinates of GEONET, GSI's network of about 1,300 continuously observing GNSS reference stations (the F5.1 solution from April 2026). Station movements are interpolated by kriging onto a grid of roughly 5 km, and the correction for any point is taken by bilinear interpolation from the four nearest grid points. Three corrections are offered:

• Steady-state correction (POS2JGD): for non-survey users aligning CLAS or PPP positions with national coordinates. Parameter files are updated about every three months and are available as text downloads, a single-point or batch web calculator (up to 30,000 points) and a WebAPI that also accepts NMEA sentences. GSI designs it to a 3 cm consistency in position and height, which it does not guarantee.
• Semi-dynamic correction: annual parameter files and the web SemiDynaEXE calculator for control-point surveys that use only GEONET stations as known points. Using the files in surveys requires GSI approval under the Survey Act.
• Earthquake and volcanic corrections: parameters on a roughly 1 km grid for affected areas, applied with GSI's PatchJGD tools.

GSI names uses including automated control of construction and farm machinery, drone logistics, mobility support and autonomous driving. The POS2JGD site is free to use; its API requires a GSI account.