Correlation between Landforms and Ground Deformation at Nisyros Volcano (Greece)

Relief represents a major element in the characterization of a landscape that can be affected even by slight modifications on its shape, often due to ground deformation. These terrain characteristics are both linked to the topography of a given area, through a Digital Elevation Model (DEM). Topographical attributes, such as slope, aspect, elevation gradients, and others, can be provided by DEM analysis and used further as input to classification methods for defining terrain units. In this study, we explore the relationship between ground deformation and landforms in Nisyros volcano, as ground deformation seems to follow existing geomorphological patterns. Possible correlations between morphological information, collected by classifying landforms on the basis of the ~30 m spatial resolution ASTER Global Digital Elevation Model, and deformation observations resulting from Differential Synthetic Aperture Radar Interferometry (DInSAR) are performed, taking also into consideration the geostructural setting of the study area. Nisyros volcano, located at the eastern part of the active Hellenic Volcanic Arc, was investigated for the time period 2002-2010, during a dormant phase where the topography is mostly described by the geological/tectonic structure. In terms of DInSAR technique, the entire archive of ENVISAT images was used, in both ascending and descending mode, to derive the deformation rates. For the geomorphic consideration Tandem Analysis was implemented through a mixed classification procedure following a principal component analysis applied to local elevation gradients, extracted considering each pixel of the DEM and its nearest neighbours. The projection of the DInSAR results on the obtained factor spaces allows evaluating the homogeneity of the deformation in the pixels belonging to the same classes.