ISPRS-Annals ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences ISPRS-Annals ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci. 2194-9050 Copernicus Publications Göttingen, Germany 10.5194/isprs-annals-IV-1-W1-223-2017 EVALUATING THREE INSAR TIME-SERIES METHODS TO ASSESS CREEP MOTION, CASE STUDY: MASOULEH LANDSLIDE IN NORTH IRAN Mirzaee S. 1 Motagh M. 2 3 Akbari B. 1 Wetzel H. U. 2 Roessner S. 2 Forest, Range and Watershed Management Organizations of Iran, Iran GFZ German Research Centre for Geosciences, Department of Geodesy, Section of Remote Sensing, Potsdam, Germany Institute for Photogrammetry and GeoInformation, Leibniz University Hannover, 30167 Hannover, Germany 30 05 2017 IV-1/W1 223 228 This work is licensed under a Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/ This article is available from https://isprs-annals.copernicus.org/articles/isprs-annals-IV-1-W1-223-2017.html The full text article is available as a PDF file from https://isprs-annals.copernicus.org/articles/isprs-annals-IV-1-W1-223-2017.pdf

Masouleh is one of the ancient cities located in a high mountainous area in Gilan province of northern Iran. The region is threatened by a hazardous landslide, which was last activated in 1998, causing 32 dead and 45 injured. Significant temporal decorrelation caused by dense vegetation coverage within the landslide area makes the use of Synthetic Aperture Radar Interferometry (InSAR) for monitoring landslide movement very challenging. In this paper, we investigate the capability of three InSAR time-series techniques for evaluating creep motion on Masouleh landslide. The techniques are Persistent Scatterer Interferometry (PSI), Small BAseline Subset (SBAS) and SqueeSAR. The analysis is done using a dataset of 33 TerraSAR-X images in SpotLight (SL) mode covering a period of 15 months between June 2015 and September 2016. Results show the distinguished capability of SqueeSAR method in comparison to 2 other techniques for assessing landslide movement. The final number of scatterers in the landslide body detected by PSI and SBAS are about 70 and 120 respectively while this increases to about 345 in SqueeSAR. The coherence of interferograms improved by about 37% for SqueeSAR as compared to SBAS. The same rate of displacement was observed in those regions where all the methods were able to detect scatterers. Maximum rates of displacement detected by SqueeSAR technique in the northern edge, older and younger part of the landslide body are about -39, -65 and -22 mm/y, respectively.