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The 1.8m Problem: Why Australia Has Two National Datums
The Indo-Australian plate moves at approximately 7 centimetres per year —one of the fastest-moving tectonic plates on Earth. GDA94, defined at 1994.0, diverged from global WGS84/ITRF realizations by roughly 1.7—.0 metres by the 2010s. ICSM officially quantifies the GDA94→GDA2020 shift as approximately 1.8m north-east, and mandates use of the official NTv2 grid transformation for all precision surveys.
Any GIS workflow treating GDA94 and GDA2020 as equivalent without transformation will accrue this error silently, with compounding drift relative to current WGS84 realizations.
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The $50,000 Geodetic Drift Liability: NAD83 vs WGS84
北米プレートは年間約2cm移動するため、NAD83(2011)とWGS84(G1762)は現在2.2メートル以上乖離しています。 高精度なNAD83地籍杭打ちに「標準的な」GPS WGS84座標を使用したことで、基礎のやり直しやインフラの配置ミスによる5万ドルの専門家責任賠償請求が発生しています。
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重要：計算結果の正確性を確認してください
座標精度はデバイスや測地系によって異なります。以下の確認を行わずに実務で使用しないでください：