Monitoring and modeling of a landslide in Kahroud, Iran, by InSAR measurements and slope stability analysis

This work demonstrates the potential of synthetic aperture radar interferometry (InSAR) based on interferometric point target analysis (IPTA) approach for landslide-induced deformation measurement. Twenty-eight Sentinel-1A images acquired between October 14, 2014, and October 27, 2016, are employed in order to measure the surface deformation associated with Kahroud landslide, northern Iran. Due to the lack of geodetic measurements and thanks to capability of processing small baseline highly coherent interferograms in the study area, the conventional small baseline subset (SBAS) time series analysis is exploited for investigation of the IPTA performance. The cross-comparison indicates some unwrapping errors in the IPTA results and removal of a large number of point target candidates due to the remained nuisance terms in the phase measurements, the deviation of the deformation behavior from a simple linear model employed by IPTA and the temporal gap in the available dataset. Two different sliding mechanisms, however, are revealed based on the SBAS time series analysis results. In the second part of the research, the slope stability analysis to characterize the slope dynamics is finally performed based on the deformation field extracted from two ascending and descending single interferograms. Accordingly, the soil shear strength parameters as well as a 3D model of the sliding surface are estimated followed by the calculation of the soil mass involved by the Kahroud landslide.