利用大地測量成果研究地殼變形－以新竹、苗栗地區為例

Abstract

本文利用1977年至1988年間三角三邊網測量觀測量做為台灣省新竹、苗栗 地區的水平地殼變形的分析，觀測量經過嚴密的偵錯計算後，可以求得各 三角點位的應變率張量因子、應變率參數、主應變率及主應變方位等。經 各項參數的分析，本研究區受到 NW-SE 方向的壓縮，此種結論與台灣所 處之歐亞板塊受菲律賓板撞擊的學說相符合，經過11年的擠壓，本研究區 約以346 度的方位位移約27.3±8.9公分。從應變率分析中，可以發現相 類似應變走向者形成相似結構區域，此種區域類似於地質結構，而且皆可 符合地質學科的解釋，本文將全區劃分為三個區塊，則各區塊的平均主應 變率及方位皆可符合當地地質結構的特性。地質構造線間的相對運動也可 以求得，橫跨斗煥坪斷層的擴張分別為13.6mm/year及10.3mm/year，橫跨 新竹斷層的擴張分別為1.6mm/year及4.7mm/year，其他營橫跨NE-SW 走向 構造線的點位間呈現壓縮作用，由此可以判斷各構造線的特性。本文探討 天文方位角對應變率模式的影響，可知加入天文方位角後，在網形的尺度 及旋轉有明顯的影響，對於應變率分析的正確與否，有值得進一步研究的 價值。 Horizontal crustal deformation in Hsichu,Miaoli,Taiwan were analysised by using the measurements of triangulation network from 1977 to 1988.Rates of the strain tensor nd rates of the strain parameters such asmum shear strain,principalstrain,and direction of the principal strain were calculated. For this local study,we can find a compression in the NW-SE direction,an extension in NE-SW direction.The agrees with thelt of plate tectionic theory in the local area well.The studyin the paper has been compressed for 11 years,which has a.9cm displacement and 346°azimuth direction. The strain patterns from a blocklike structure.This structure have some similarities with the tectonic structure.The study area was divided into three different blocks.Every block's strainrn agrees with geological study well. Relative movements of the tectonic line were also carried out.Across the Douhuanping fault,it has an extension rate 13.6 mm/year and 10.3mm/year;while across the Hsinchu fault,theon rate is 1.6mm/year and 4.7mm/year.The stress of thering points which across the NE-SW tectonic line well also compression.Consequently,the characteristics of thesere lines can be determined. The effects of strain pattens which contribute by the valuesthe astronomical azimuth were also discussed.The effects of awork by adding the astronomical azimuth include scale andcomponents.However,it is necessary to make a furthererstand if the analysis of strain patterns is