Comparing the results of PSInSAR and GNSS on slow motion landslides, Koyulhisar, Turkey

There are numerous methods used nowadays to monitor landslide movements. Of these methods, Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) are the ones that are most commonly used. In this study, the amounts of movements acquired via these two methods were compared and relations between them were analysed. The Koyulhisar landslide region was selected as the field of study. In this study, 10 Envisat images of the region taken between 2006 and 2008 were evaluated using Persistent Scatterers Interferometric Synthetic Aperture Radar (PSInSAR) technique and annual velocity values at the direction of line of slight at PS points were obtained for the region of interest. The velocity values were then obtained from PSInSAR results and compared with those obtained from six periods of GNSS measurements that were performed between April 2007 and November 2008 on Koyulhisar Landslide area after which the relationship between the two was analysed. Two different movement models from GNSS and PSInSAR results were fit to the landslide region. The velocity values estimated from these movement models for the region were compared and correlation between them was determined. As a conclusion, a high correlation of r = 0.84 was determined between the models obtained from nine GNSS points, except one point at the city centre, and PSInSAR.