Monitoring of Surface Deformation in Northern Taiwan Using DInSAR and PSInSAR Techniques

Abstract

We investigated the surface deformation of the northern Taiwan area, including the Taipei basin and its surrounding mountainous areas of the last fifteen years using the ERS-1, ERS-2 and ENVISAT SAR images. Although the Taipei basin now is well developed and amenable to research gathering using the Differential Interferometric Synthetic Aperture Radar (DInSAR) technique, the mountainous areas surrounding the basin are densely covered with various vegetation throughout different seasons inducing high noise ratio in interferograms. Therefore the DInSAR technique is ineffective for observation of surface deformations of these areas. As a result, we developed the Persistent Scatterer (PS) InSAR technique to extract the phase signal of the chosen PS points for this study. Our analysis result shows that the atmospheric disturbance and DEM residual can be successfully reduced and the precise information of surface deformation can be effectively obtained by the PSInSAR technique not only in the basin but also in the mountainous areas. Integrating the DInSAR and PSInSAR results, we observed conspicuous deformation events in northern Taiwan including: (1) the slight uplift in the Western Foothills, the Tatun volcanoes, the Linkou Tableland and the Taoyuan area; (2) the subsidence at the border of the Taipei basin; and (3) relative slight uplift rebound in the center of Taipei basin. The displacements along the Shanchiao, Chinshan, and Kanchiao Faults are large enough to be observed; the Taipei, Hsinchuang, and Nankang Faults are too small and cannot be discerned. Further comparison between the DInSAR, PSInSAR, and their corresponding leveling data shows a very coincidental pattern and measurably improves the authenticity of radar interferometry.

Using differential SAR interferometry to map land subsidence: a case study in the Pingtung Plain of SW Taiwan

“…Besides, the SBAS (small baseline subset) technique developed by Berardino et al (2002) and StaMPS (Stanford method for persistent scatterers) developed by Hooper et al (2004) are also based on the same idea of PSInSAR technique with different name. In addition, several studies have been successfully applied by using this technique to demonstrate deformation in Taiwan (Chang et al 2010;Tung and Hu 2011).…”

Surface deformation in the Himalaya and adjoining piedmont zone of the Ganga Plain, Uttarakhand, India: Determined by different radar interferometric techniques

“…The DInSAR has great potential for mapping large movements associated with large earthquakes (i.e. Mw > 7, such as the Mw 7.6, Chi-Chi earthquake, Taiwan of 1999) and monitoring surface deformations in well developed areas where the coherence is good (Chang et al, 2010). The term 'coherence' is used in interferometry to indicate that the phase information between two waves is the same.…”

“…4b). These stable back-scatterers are called the ''Persistent Scatterers (PS)'' points (Hooper et al, 2004(Hooper et al, , 2007Chang et al, 2010;Yen et al, 2011). In general, these PS points can be either man-made or natural such as buildings, tree trunk, rock outcrops or boulders (Hooper et al, 2004).…”

Elucidating the geometry of the active Shanchiao Fault in the Taipei metropolis, northern Taiwan, and the reactivation relationship with preexisting orogen structures

“…GPS surveys of the Taipei area showed WNW‐ESE extension with a slow rate of 0.08 μstrain/yr across the fault [ Yu et al ., ]. Asymmetric tectonic subsidence related to the Shanchiao Fault was illuminated through 30 year long leveling data [ Chen et al ., ] and recent interferometric synthetic aperture radar (InSAR) data [ Chang et al ., ]. Holocene paleoseismic events were proposed at ~8500, ~9200, and ~11100 years B.P.…”