Pre-seismic displacements of the 2008 Wenchuan earthquake from temporarily stable points in PALSAR interferograms

Lei Zhang(1), Xiaoli Ding(1) and Makoto Omura(2)

(1) The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
(2) Kochi Women's University, 5-15, Eikokuji-cho, Kochi, Japan


On 12 May 2008, an earthquake with a magnitude of 8.0 Ms struck Wenchuan County, Sichuan Province, China, which caused massive damages and a great number of casualties. A 300-km-long fault slip occurred as a result of the earthquake. This paper discusses the mapping of the pre-seismic displacements associated with the earthquake with PALSAR interferometry. Six ascending frames with interferometric pairs spanning 46 to 92 days are used to cover the whole affected area.

When performing the SAR interferometry, we employed a new analysis method that could be used to identify and extract temporarily stable points (TSP) between two SAR acquisitions. After the LOS displacements in each interferograms are determined, the displacement time series covering the period from January 2007 to May 2008 are generated based on a low-resolution mosaic method, which shows that considerably large displacements occurred along the fault before the earthquake.



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