應用多時雷達差分干涉技術探討竹苗地區地形變遷

Abstract

相較於傳統測量，多時雷達差分干涉技術(Multi-Temporal InSAR, MT-InSAR)能夠獲取大範圍且高精度的地表變形資訊，本研究共使用ALOS PALSAR於2007年至2010年間的12幅雷達影像，進行PSInSAR與StaMPS/MTI兩種不同之MT-InSAR處理，得到各時間段之衛星視線方向(LOS)平均速度場和時間序列，並以相同時間內的26個GPS連續測站加以改正與比對得到垂直位移速度，用以監測竹苗地區活動斷層的變動以及苗栗縣南庄鄉山區鹿場部落的邊坡滑動。 新城斷層上盤及新竹斷層上盤之研究成果皆為抬升，最大值約為PSInSAR的11.13 mm/year以及StaMPS/MTI的8.45 mm/year，新竹斷層上盤之最大值約為PSInSAR的10.87 mm/year與StaMPS/MTI 5.79 mm/year，新竹斷層下盤西北延伸至沿海shju測站抬升現象逐漸平緩或改為下陷，往北過頭前溪則新城斷層附近改為下陷為主。 鹿場地區的StaMPS/MTI成果顯示，位於崩崖處東側的下陷速度約為20~40 mm/year大於崩崖處西側5~15 mm/year，另外，經由時間序列的分析可以發現鹿場臺地邊坡滑動情形與降雨量有關聯性，當春夏雨季累積到一定降雨量或是歷經颱風豪大雨後，地表的下陷量會明顯增大。PSInSAR成果顯示東側臨鹿場溪有大規模崩塌的趨勢，下陷量約為0~25 mm/year，在崩崖面西側附近則以5~15 mm/year抬升為主，遠離崩崖面則抬升趨勢減緩為0~5 mm/year或轉為0~10 mm/year下陷。 PSInSAR與StaMPS/MTI經GPS比對後之方均根誤差分別為8.56 mm/year與7.60 mm/year，點位密度則是101.3 points/ km2與43.90 points/ km2。

Multi-Temporal InSAR (MT-InSAR) has the capability to produce wide area and high accuracy deformation data. This study used 12 SAR images from ALOS PALSAR during 2007-2010 with PSInSAR and StaMPS/MTI method to produce Line-Of-Sight mean velocity fields and time series. The results were corrected and validated by 26 GPS stations in the same time interval to infer vertical motion of ground, which was established for monitoring the active faults in Hsinchu and Miaoli area and the landslide of Luchang. The results show that the hanging wall of Hsinchu and Hsincheng fault are both uplifting. The maximum rate is 11.13 mm/year from PSInSAR and 8.45 from StaMPS/MTI on hanging wall and 10.87 mm/year from PSInSAR and 5.79 mm/year from StaMPS/MTI on footwall. The uplifting rate is relatively gentle and changes to subsidence on the footwall of Hsinchu fault to coastwise and on the north of Toucian River. The results in Luchang show that, the subsidence rate is about 20~40 mm/year on the east side of cliff, which is bigger than 5~15 mm/year on the west side of cliff. Furthermore, the landslide is correlated to the rainfall after time series data analyze. The root mean square (rms) value of PSInSAR and StaMPS/MTI are 8.56 mm/year and 7.60 mm/year after validating with 26 GPS stations. The density are 101.3 points/ km2 for PSInSAR and 7.60 mm/year for StaMPS/MTI.