Quantification of mass wasting volume associated with the giant landslide Daguangbao induced by the 2008 Wenchuan earthquake from persistent scatterer InSAR

The spaceborne interferometric synthetic aperture radar (InSAR) with persistent scatterer (PS) is utilized to retrieve the spatial characteristics of the largest coseismic landslide Daguangbao, induced by the Ms 8.0 Wenchuan earthquake in Sichuan Province, China. The available twenty interferometric pairs with good coherence selected from the ALOS/PALSAR imagery data covering the Longmen Shan mountainous area are used in the study. We have constructed a natural geodetic observation network with numerous scattered bare rocks emerging after the earthquake and coseismic landslide events, which are effectively recognized as the radar persistent scattering objects. The spatial connections between adjacent PS are established to form observation baselines with differential parameters related to topography and deformation, which are determined by the least squares method from time-series interferometric phase analysis. The post-seismic topographic change relative to the pre-seismic over the landslide area is spatially mapped from the PS network adjustment solution. The quantitative estimation of local elevation change, mass sliding volume and deposit thickness associated with the landslide is conducted. The spatial pattern of mass movement suggests that the giant landslide is characterized by a major sliding length of 4350 m along the NE–SW directions with an extension width of 3400 m along the Huangdongzi gully, and a peak height change of 535 m in the vertical direction. The affected area of landslide mass movement reaches 7.2 km2 with the volume up to 1.28 billion m3. The study also demonstrates the potential of persistent scatterer InSAR technique as an alternative to allow the quantitative measurement of mass wasting volume associated with earthquake-induced giant landslides.