NHESS Natural Hazards and Earth System Sciences NHESS Nat. Hazards Earth Syst. Sci. 1684-9981 Copernicus Publications Göttingen, Germany 10.5194/nhess-14-675-2014 Landslide observation and volume estimation in central Georgia based on L-band InSAR Nikolaeva E. 1 Walter T.R. https://orcid.org/0000-0002-9925-4486 1 Shirzaei M. 1 2 Zschau J. 1 Department 2 – Physics of the Earth, Helmholtz Center Potsdam – GFZ German Research Center of Geosciences, Potsdam, Germany now at: School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-6004, USA 25 03 2014 14 3 675 688 Copyright: © 2014 E. Nikolaeva et al. 2014 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://nhess.copernicus.org/articles/14/675/2014/nhess-14-675-2014.html The full text article is available as a PDF file from https://nhess.copernicus.org/articles/14/675/2014/nhess-14-675-2014.pdf

The republic of Georgia is a mountainous and tectonically active area that is vulnerable to landslides. Because landslides are one of the most devastating natural hazards, their detection and monitoring is of great importance. In this study we report on a previously unknown landslide in central Georgia near the town of Sachkhere. We used a set of Advanced Land Observation Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) data to generate displacement maps using interferometric synthetic aperture radar (InSAR). We detected a sliding zone of dimensions 2 km north–south by 0.6 km east–west that threatens four villages. We estimated surface displacement of up to &sim;30 cm/yr over the sliding body in the satellite line-of-sight (LOS) direction, with the largest displacement occurring after a local tectonic earthquake. We mapped the morphology of the landslide mass by aerial photography and field surveying. We found a complex set of interacting processes, including surface fracturing, shear and normal faults at both the headwall and the sides of the landslide, local landslide velocity changes, earthquake-induced velocity peaks, and loss in toe support due to mining activity. Important implications that are applicable elsewhere can be drawn from this study of coupled processes. <br></br> We used inverse dislocation modelling to find a possible dislocation plane resembling the landslide basal décollement, and we used that plane to calculate the volume of the landslide. The results suggest a décollement at &sim;120 m depth, dipping at &sim;10° sub-parallel to the surface, which is indicative of a translational-type landslide.

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