| 摘要: | 台灣位在菲律賓海板塊與歐亞⼤陸板塊的邊界，地處環太平洋地震帶，⾧
年受到造⼭運動的影響，造成了東半部的多⼭地形並且有頻繁的地震。2018年2
⽉6⽇發⽣了芮⽒規模6.26的花蓮地震，震央在花蓮外海，主要的變形區域集中
在⽶崙斷層與嶺頂斷層兩個主要的斷層的周圍。在這場⼤地震後零星的餘震持
續的出現，且兩個斷層位置就位在花蓮平坦市區，該地區主要有花蓮市與吉安
鄉兩個⾏政區，⽽兩個⾏政區正是花蓮地區⼈⼝⾼度密集的位置，因此持續監
測此地區地表變形⾮常重要，本研究主要監測花蓮兩個⾏政區的同震與震後變
形。過去應⽤在偵測地表變形主要仰賴⽔準測量與GPS連續測站資料，本研究
使⽤雷達⼲涉技術（InSAR）應⽤Sentinel-1A和1B雷達影像針對⽬標區域進⾏
地表變形觀測，其中DInSAR技術適合使⽤在單⼀事件觀測，所以將這項技術使
⽤在同震位移觀測，⽽PSInSAR技術則適合使⽤在時間序列的觀測，所以將這
個技術應⽤在震後地表變形的觀測。同震分析結果顯⽰在花蓮市區有-172 mm，
在嶺頂斷層西側277 mm⽽在東側則只有190 mm皆是在視衛星⽅向上，並結合
GPS、斷層線位置、⽔準測量結果與地震調查報告進⾏相關驗證⽐對有⾼度的
同調性。震後分析在時間序列上將參考點設置在鄰近的GPS連續觀測站點，研
究成果顯⽰PSInSAR與GPS觀測的資料呈現⾼度相關，且分析的成果顯⽰⽶崙
斷層從南往北變形由遠離轉為接近衛星⽅向，市區沿海地區接近衛星趨勢明顯
為-9.34~-7.45 mm/year，從花蓮⾼級⼯業職業學校往花蓮航空站從接近衛星2.05
mm/year變化⾄接近衛星7.07 mm/year，花蓮觀光漁港區域為遠離衛星趨勢3.87~-7.57 mm/year，慈濟⼤學⾄北埔⽕⾞站接近衛星情況⾮常劇烈為7.79 mm/
year~14 mm/year，美崙⼯業區整體的震後變形趨勢為6.83~10.21 mm/year。在
南部的嶺頂斷層附近變形為遠離衛星約為-17.69~-18.27 mm/year，位在斷層西側
遠離衛星⽅向位移略⼩為-11.33 mm/year~-15.36mm/year，⽽斷層東側狀況較明
顯為-17.43mm/year~-21.23mm/year，嶺頂斷層往西邊銅⾨⽅向則由遠離衛星⽅
向-2.35mm/year轉變為接近衛星⽅向11.46mm/year。
關鍵字：地表變形、Sentinel - 1、PSInSAR、DInSAR;The island of Taiwan is located at the junction of the Eurasian plate and the
Philippine plate. This location, in the Southeast Asia Circum-Pacific Belt, increases
the probability of earthquakes, which are regularly occurring in Taiwan. On February
6, 2018 at 23:50:41, an earthquake occurred in north-eastern part of Taiwan with the
epicenter close to coast, near the city of Hualien. The earthquake was ML6.26 and
caused serious casualties. Although the epicenter was located off the coast of Hualien,
the deformation around Hualien was massive. Two major faults, the Milun fault and
the Lingding fault, are located within dense populated urban area. Therefore, it is
important to continuously monitor the deformation around the region. This study used
Sentinel 1A and 1B SAR images to analyze the co-seismic deformation in Hualien
with Differential Interferometry Synthetic Aperture Radar (DInSAR). In addition, the
post-seismic deformation analyzed with the Persistent Scatterers Interferometric
Synthetic Aperture Radar (PSInSAR) was used to investigate long-term changes. The
PSInSAR and DInSAR analyses were validated with official GPS observation data.
The co-seismic results agree with the co-seismic leveling survey around the location
of the Milun and Lingding fault lines. Generally, the deformation of the urban area in
Hualien can be described by the line of sight (LOS) direction -172 mm. On the west
side of the Lingding fault, 277 mm close to the satellite in the LOS direction, and 190
mm closer to satellite in the east side were detected. The results of post-seismic
deformation correlate reasonably with the GPS data. The post-seismic results show
that the deformation of the Miluun fault changes from south to north, from far away
from the satellite to close to the satellite. The away from satellite trend in urban
coastal areas is obviously -9.34 ~ -7.45 mm/year. From Hualien Industrial Vocational
Senior High School to Hualien Airport, the close to the satellite changes from 2.05
mm/year to 7.07 mm/year, and the Hualien Seafood Fishing Port area is away from
satellite -3.87~-7.57 mm/year. The close to satellite from Tzu Chi University to Beipu
Railway Station is 7.79 mm/year~14 mm/year, and the deformation trend at Meilun
Industrial Zone is 6.83~10.21 mm/year. The Lingding fault in the south with an
average away from satellite -17.69~-18.27 mm/year, the west side of the fault was
slightly less -11.33 mm/year~-15.36 mm/year, whereas the east side of the fault
-17.43 mm/year~-21.23 mm/year. The fault turns into close to satellite of -2.35 mm/
year ~11.46 mm/year in the direction of Tongmen.
Keywords: Land deformation, PSInSAR, DInSAR, Sentinel-1 |
