台灣土地變動特性與地籍相關問題之探討

Discussion on the Characteristics of Land Movement and Cadaster Related Issues in Taiwan

由於台灣位處全球最活耀的環太平洋地震帶，菲律賓海板塊以每年約8.2公分的速率向歐亞板塊聚合，使得台灣土地有不同程度線性及非線性運動，造成基本控制測量產生明顯位移，連帶使得如地籍測量等應用測量精度失準而產生糾紛造成爭議。本研究藉由文獻分析爬梳歷年地震資訊，並得7次地震造成水平變位達公尺等級，尤其對於「九二一集集大地震」地表位移及對地籍影響進行相關研究蒐整分析，確認台灣土地活動對大地基準造成嚴重的影響，而地籍經界線也因此與實地現況嚴重不符。台灣現行的靜態測量基準，為因應變動的土地特性，有朝時變基準，採動態或半動態模式，並納入震間變形的改正探討。惟經本研究分析，似仍未能有效解決地籍問題。故對台灣的地籍作業因應土地變動特性所面臨之不足，本研究提出：1.律定時變基準影響地籍標示變更時機、2.採用測量基準模式應公開、3.法條規範因應修正、4.強化作業人員訓練、5.社會認知調整等建議，供後續對於解決地籍作業與土地變動問題之因應參考。

Taiwan is located in the most active circum-Pacific seismic zone in the world. The Philippine Sea plate continues to converge towards the Eurasian plate at a rate of about 8.2 cm/yr, causing the land to have varying degrees of linear and nonlinear motion, which results in significant displacement of the basic survey, and jointly effects the measurement accuracy of applied survey. As a result, it causes cadastral survey inaccurate and disputes. This study sorts out the recorded earthquake information in Taiwan over the years and finds that 7 of the earthquakes caused horizontal displacements up to the meter level. Especially, it analyzes the surface displacement of the ''921 Chi-Chi Earthquake'' and its impact on the cadaster, confirming that Taiwan's land activities have indeed had a serious impact on the geodetic datum. Therefore, the cadastral boundary line is seriously inconsistent with the actual situation on the ground. This study discusses the feasibility of dynamic and semi-dynamic operations with time-variant datum, and incorporates inter-seismic deformation factors to correct the problems faced by Taiwan's current static datum in response to changing land characteristics. Regarding the problems faced by Taiwan's cadastral operations in response to land movement, this study puts forward: 1. Determine the timing of the impact of time-varying datum on cadastral indications, 2. The adoption of geodetic datum should be transparent, 3. Laws and regulations should be amended accordingly, 4. Strengthen the training of surveyors, 5. Social cognition adjustment for cadaster, for follow-up references to solve the problems of cadastral operations and land movement.