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How Much Does Tokyo Datum Shift?
The old Tokyo Datum shifts by over 400 meters to the northwest when converted to modern, global coordinates like WGS84 or JGD2011. Additionally, the 2011 Tohoku earthquake caused unprecedented physical crustal deformation, requiring localized shifts of up to 5 meters using specific grid files to achieve JGD2011 accuracy.
Data & Tolerance Table
The following table outlines the exact parameters and tolerances associated with this scenario to help you gauge the severity of the geodetic error.
| Transformation Phase | Shift Magnitude | Underlying Cause |
|---|---|---|
| Tokyo Datum to JGD2000 | ~400 to 450 meters | Ellipsoid diff (Bessel to GRS80) |
| JGD2000 to JGD2011 | 0.1m to 5.0+ meters | 2011 Tohoku Earthquake shift |
| Elevation Offset | ~40 meters | Geoid to Ellipsoid separation |
| Total Legacy Shift | > 400 meters | Combined systemic network update |
Geodetic Formula
JGD2011_Coordinates = Tokyo_Coordinates + (tky2jgd.gsb Grid Shift) + (touhokutaiheiyouoki2011.gsb Earthquake Shift)
Official Regulatory Compliance Reference
Geospatial Information Authority of Japan (GSI) / EPSG:6714 PROJ Pipeline specification.
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Warning: Verify Your Calculation
Coordinate accuracy varies by device and datum. Do not use these results for legal or construction purposes without checking:
GPS Accuracy Alert
Your phone's GPS can be off by 30 meters. This can cause critical errors in your data.
Check My Accuracy →Datum Shift Risk
Using the wrong coordinate system (e.g. WGS84 vs NAD83) creates a permanent 1-meter offset.
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