Application of Sub-Pixel Image Correlation to near Field Ground Deformation Measurements of Wenchuan Earthquake
详细信息
- 责任者：Liu Yunhua (State Key Laboratory of Earthquake Dynamics ; Institute of Geology ; China Earthquake Administration ; Beijing 100029 ; China) ; Shan Xinjian
- 刊名：Seismology and Geology
- 出版年：2013
- 卷期：35(1)
- 关键词：汶川地震2008 ; Wenchuan earthquake 2008 ; 航空摄影 ; aerial photography ; 地形变 ; ground deformation ; 四川 ; Sichuan Province
- 页码：p.138-150
- 图表：illus., 2 tables, 22 refs.
- 分类号：2100
- issnNo：ISSN0253-4967
- isbnNo：CN11-2192/P
摘要
The distribution and characteristic of ground deformation is a key issue in geodesy,which brings insight into the geometry of the ruptured fault and seismic hazard assessment in the future in the surrounding areas. It also provides better constraint conditions for geophysical inversion. Compared with field research,satellite imagery regularly provides detailed and spatially comprehensive images and is a most valuable alternative especially for the study in remote areas. So,observing seismic rupture is urgent after earthquake. InSAR is useful for measuring ground displacement,but the technique has severe limitations that are mainly due to data decorrelation and signal saturation,and it does not generally provide measurements in the near-fault area where large displacements occur. In this paper,the sub-pixel correlation method and SPOT image are used to map the Wenchuan earthquake rupture and to identify the faults activated by the earthquake. A computation is introduced of the inverse projection matrices for which a rigorous resampling is proposed. Image registration and correlation is achieved with an iterative unbiased processor that estimates the phase plane in the Fourier domain for subpixel shift detection,then the earthquake deformation field is derived.The results indicate that the Wenchuan earthquake produced at least surface ruptures on two faults along the Longmenshan Fault,the main rupture named Beichuan-Yinxiu rupture zone(Longmenshan town-Gaochuan in this map)and the secondary rupture named Hanwang rupture zone.The former is characterized by dextral-slip thrusting with a horizontal displacement of 4～6m in average and a dextral-slip displacement of 1～3m near Gaochuan town.The latter is characterized by pure thrusting,with horizontal displacement 1～2m in average. There is no obvious ground rupture along Wenchuan-Maoxian Fault.The research indicates that sub-pixel correlation using optical image can be a powerful complement to differential radar interferometry,which can measure ground displacement near the fault zone.The study also shows that earthquake displacement fields can be calculated by remote sensing technology.The surface rupture can be traced and the meizoseismal area can be located by this method. Compared with field research,satellite imagery regularly provides detailed and spatially comprehensive images and is a most valuable alternative especially for the study in remote areas.
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