Surface deposits and landslide inventory map of the area affected by the 1997 Umbria-Marche earthquakes

On 26 September 1997 the Umbria-Marche area of Central Italy was shaken by two severe earthquakes of 5.6 and 5.8 local magnitude. On 14 October 1997 the same area experienced another earthquake of similar magnitude. Following the main shocks we performed field surveys to map landslides triggered by the earthquakes, and to determine the main landslide types, and whether there was a relationship between pre-existing landslide deposits and the seismically induced failures. Information collected at 220 sites revealed that most of the fractures were related to the presence of human structures, and that landslides were mostly rock falls, minor rock-slides and topples. We mapped new fractures in a few pre-existing landslide deposits, but no major landslide was reactivated to the point of catastrophic failure. For an area of about 900 km 2 located around the earthquake epicentres, standard photo-geological techniques and field surveys enabled us to prepare a detailed map of surface deposits, showing landslides, alluvial fans and other types of debris. A geographical database including all the available information was prepared to investigate the relationship between co-seismic landslides and fractures and the distribution of surface deposits, including landslides.