ИСТИНА

The Black Sea coast of the Great Caucasus is a region of high landslide risk. In recent years landslide risk assessment has become vital because of strongly increased human-induced impact dealt with construction of the Sochi-2014 Olympic Games facilities. We studied the landslide activity in the area of the Big Sochi using the StaMPS PS-InSAR and SBAS methods. We incorporated all available radar images from the satellites with different wavelengths: 17 ALOS images, 13 Envisat images, 17 TerraSAR-X images. For all of these three sets of images we identified persistent scatterers (PS) with a density of more than 350 PS/km even for rural areas. Many areas of relatively high surface displacement rates located using the SAR data appeared to match with the landslide inventory maps. . We present time series for the most active landslide areas of the Big Sochi. The calculated average surface line-of-sight (LOS) displacement rates vary from 15-20 mm/year up to 60 mm/year. For some places with extreme values of LOS displacement rates the values of displacement rates in the down the slope direction were also estimated. Results obtained with the StaMPS software were compared to those obtained by DePSI and GiANT (SBAS, NSBAS) methods. Analysis of the time series made it possible to determine periods of activity and relative stability of the landslides and compare them to the ground observations. Detailed analysis of the time series was performed for the Baranovka landslide where very strong movements during 23-24 January 2012 damaged 35 houses. Obtained results illustrates high efficiency of SAR Interferometry in monitoring of landslide activity in the areas of the Great Caucasus where landslides are numerous.