Updating landslide inventory maps in mountain areas by means of Persistent Scatterer Interferometry (PSI) and photo-interpretation: Central Calabria (Italy) case study

Conventional methods used to detect slope instability and map geomorphologic processes, es-pecially in mountain areas, can benefit from remote sensing analyses, e.g. optical and radar satellite data. We illustrate the contribution of Persistent Scatterer Interferometry (PSI) analyses and photo-interpretation for the updating of pre-existing landslide inventory maps in mountain areas, through the case study of Central Ca-labria, located in southern Italy with an extension of 4,470 km2. We used 108 ENVISAT ascending images (20 m ground resolution) acquired in 2003-2009 and processed with the PSP (Persistent Scatterer Pairs) tech-nique, 1 optical image acquired by SPOT satellite (2.5 m resolution), and digital orthophotos with 1 m resolu-tion covering the whole investigated area. All these data were integrated and combined with additional ancil-lary information (e.g. topographic, geological and land use maps). 980 landslides (23.9% of pre-existing inventory) were updated by means of PSI information and 64 new landslides were also detected. The state of activity and the intensity of these landslides were also updated and/or evaluated, showing that 22% and 2% of the updated inventory include active (919 landslides) and reactivated (93 landslides) phenomena respectively. The outcomes of the integrated radar-interpretation and photo-interpretation methodology for Central Calabria and its operative usefulness for civil protection authorities represented a valuable proof of the reliability of this approach for updating landslide inventory maps in mountain areas at regional scale.