Criteria for the elaboration of susceptibility maps for DGSD phenomena in central Italy

In this research we analyze the overall requirement and use of para- meters derived from geomorphic techniques for Deep-seated Gravita- tional Slope Deformation (DGSD) susceptibility assessment in the Cen- tral Apennine (Umbria-Marche area - Central Italy). The geometric pa- rameters characterizing the topography affected by DGSD are investi- gated by remote sensing data. In particular, Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) improved with Land- sat ETM+ imageries are used to detect the topography signature repre- sentative of DGSD susceptibility. Landsat ETM+ data are processed with Spectral Mixing Analysis (SMA). The topographic DGSD signa- ture is determined by different topographic parameters such as slope, relief, aspect and curvature which can be used as a DGSD index de- gree. To characterize important physical properties of the aforesaid sig- nature, the linear mixing model between the dark surface endmember and both the substrate and vegetation endmembers was used. That model highlights the extent to which shadowing and non-reflective sur- faces, combined with illuminated substrate and vegetation at sub-pixel scale, can modulate spectrally mixed ETM+ reflectances in a ridge topography within the DGSD signature. The final results indicate that when incorporated with optical SMA of the Landsat ETM+, the SRTM analysis should improve the capacity for mapping and identifying DGSD in specific landscapes.