重大地震對臺灣地區e──GNSS系統營運因應之研究

A study on the impact of e-GNSS system in Taiwan and its operation due to severe earthquakes

e-GNSS即時動態定位系統提供2公分定位精度的即時動態定位服務，現為國內重要的空間資訊蒐集工具，惟臺灣位於板塊碰撞地區，長期擠壓造成地表持續位移，e-GNSS系統須配合更新坐標以維持基準站間之高精度相對關係。107年2月6日晚上23點50分（UTC 15：50），花蓮縣近海發生規模6級淺層地震，經檢測結果，最大位移量約為45公分（交通部中央氣象局之花蓮氣象站，HUAL），因應此狀況，內政部國土測繪中心更新區域內11個基準站坐標，辦理53個基本控制點檢測，結合兩者成果更新三維坐標轉換模型，經動態檢測43個更新後之基本控制點，精度符合國土測繪中心預期。未來針對突發的大地震，內政部國土測繪中心應啟動應變機制，透過檢測、坐標及模型更新等作為，維持系統服務效能與精度，同時亦應檢測區域內之基本控制點，確認其精度符合後續應用測量使用。

The e-GNSS real-time kinematic positioning system (e-GNSS for short) provides the real-time RTK service with 2 cm precision and has been used for geospatial data collection. The e-GNSS updates the CORS coordinates regularly to keep the interrelationship because of the surface displacement in Taiwan. The 6.2 magnitude earthquake made several residential buildings either collapsed or tilted on 6 Feb, 2018 at 11:50 PM, and the biggest displacement is about 45 cm (HUAL). National Land Surveying and Mapping Center (NLSC) updated 11 CORS' coordinates, 53 basic control points and the transformation model after detecting and recalculating the displacement. The results show the horizontal precision is less than 5 cm, and the vertical precision is less than 10 cm. By this experience, after a severe earthquake, it is necessary that NLSC recalculate the system coordinates and the transformation model to keep the service in accurate precision. Meanwhile, NLSC also should examine the precision of basic control points in the region to ensure the precision fits surveying work.