A case study on co-seismic ground deformation of the Wenchuan earthquake using L-band and C-band SAR interferometry

Synthetic aperture radar interferometry (InSAR) has been widely used for the co-seismic ground deformation monitoring. In this paper, The L-band SAR datasets acquired by ALOS PALSAR and C-band acquired by Envisat ASAR are tested respectively for monitoring the co-seismic ground deformation in the area of Dujiangyan, where the Whenchuan Ms8.0 earthquake occurred on May 12, 2008. The displacement on line of sight has been acquired with two-pass DInSAR processing. It is also found that the C-band SAR data results generally have lower coherence over high vegetated and rugged areas, while the L-band SAR with comparatively longer wavelength is more suitable for monitoring the deformation where large displacement over a small spatial extent occurs and the mountainous terrain. However, current satellite radar interferometry, because of its single-frequency signal structure, is hard to measure ground deformation with large gradients as it produce very dense fringe patterns, which cause that the ground displacement deformed in the faults cannot be measured. Although the longer wavelength of the radar signal is less susceptible to high deformation gradients, loss of correlation often still occurs in the faults caused by earthquake. So it is necessary to propose techniques which can monitor large-gradient deformation and the data fusion methods of multi-source satellite SAR images.