MONITORING OF LANDSLIDE DISPLACEMENT IN SEMIROM, IRAN, USING SAR INTERFEROMETRY

Landslide is a geological phenomenon that is among the most catastrophic natural hazards in the world. Depending on their scales, landslides can cause heavy damages to human lives and infrastructure. This phenomenon occurs when the stability of slop changes from stable condition to an unstable condition. The major reason of landslide is the change in gravity and its intensity by factors such as ground water pressure, erosion caused by rivers, rain, lack of vegetation cover, soil structure, vibration from machines, and etc... . Therefore, detection and monitoring of mass movement in susceptible areas may help mitigate hazards associated with landsliding.

Various ground-based geodetic methods such as GPS and leveling have been developed to assess landslide hazards. The main limitation of these methods is that they can’t provide continues map of deformation. Synthetic Aperture Radar Interferometry (InSAR) is widely used in recent decades to monitor movement of the ground surface associated with landslides, subsidence, earthquakes, volcanoes deformation, ice sheet and glacier movement. This technique relies on processing of two SAR images over the same area with a short baseline. The displacement is measured by calculating the phase difference between the two images acquired in the slant range geometry. The technique provides detailed maps of surface deformation with centimeter accuracy over wide areas (> 100 km2).

Our data consist of 28 ASAR images, which were acquired by the Envisat satellite in both descending and ascending orbits. We examine the InSAR time-series technique of Small Baseline (SBAS) approach to derive the spatio-temporal characteristic of mass movement in Semirom.Field observations performed following this InSAR survey revealed that there were two important landslides in the area that are in the main road connecting the Semirom to the Yasoj: one stands on the north slope of the road and the other one is in the next curve of the road and stands on the south slop of it. As these landslides are on the hillside of the road, pose a serious threat to this infrastructure. Because the rain decrease in recent year in Semirom, The road haven’t been damage yet .So monitoring and measurement of these landslides in order to doing something for recompense is necessary.