The study areas are located in Umbria, central Italy, where climate is Mediterranean and rainfall occurs mostly from October to December and from March to May. In the region crop out sedimentary rocks, pertaining to the Umbria-Marche stratigraphic sequence, Lias to Eocene in age, overlaid by lake deposits, lower Pliocene to Quaternary in age, and by fluvial deposits of Recent age. The lake and fluvial deposits host deep-seated and shallow aquifers exploited for human and agricultural uses. The structural setting is complex, and results from the superposition of two tectonic phases associated to the formation of the Apennines mountain chain. The area is seismically active, and earthquakes with local magnitude ranging between ML 4.6 and ML 5.8 have occurred repeatedly. The last earthquake sequence in the area occurred between May 1997 and April 1998. Due to the geological and climatic settings, landslides are abundant in the area and contribute to shape the landscape. More than 80% of the area is covered by vegetation, including 41% forest, 10% grassland, and 42% cultivated areas. The research will focus mainly in two study areas: 1) the Collazzone basin and 2) the town of Assisi.
The Collazzone study area extends for 78.89 km2 in Umbria, central Italy, with elevations ranging between 145 m along the Tiber River flood plain and 634 m at Monte di Grutti. Landscape is predominantly hilly, and lithology and the attitude of bedding planes control the morphology of the slopes. Valleys oriented N–S are shorter, asymmetrical, and parallel to the main direction of the bedding plains, whereas valleys oriented E–W are longer, symmetrical, and mostly perpendicular to the direction of the bedding planes. In the area crop out sedimentary rocks, including: (i) recent fluvial deposits, chiefly along the main valley bottoms, (ii) continental gravel, sand and clay, Plio-Pleistocene in age, (iii) travertine deposits, Pleistocene in age, (iv) layered sandstone and marl in various percentages, Miocene in age, and (v) thinly layered limestone, Lias to Oligocene in age. Mass movements in the area include shallow soil slides and flows, deep-seated slides and flows, and compound failures. Shallow landslides occur primarily on cultivated or abandoned areas, and are rare in forested terrain.
The town of Assisi extends along the NW sector of the mountain ridge represented by the Monte Subasio, a distinct physiographical feature in central Umbria, and is bounded to the SW by the ample Valle Umbra plain. Sedimentary rocks crop out in the area. Layered and massive limestone, marl, and clay pertaining to the Umbria-Marche stratigraphic sequence, Lias to Eocene in age, are overlaid by lake deposits, lower Pliocene to Quaternary in age, and by fluvial deposits, recent in age. Ivancich is a neighborhood in the Assisi municipality located SE of the mediaeval part of the town. Built mainly in the period 1960 – 1970, the neighborhood is a residential area of one- to three-storied private homes, and it hosts the Assisi hospital and a Franciscan convent. In the area, a deep-seated landslide is present. Geomorphological, geotechnical, and topographical investigations revealed that the Ivancich landslide is an old (ancient) translational slide that involves the debris deposit that covers the bedrock, represented by a pelitic sandstone unit. More recent, slides have developed inside the old landslide deposit. The recent slope failures have caused damage to roads, private and public buildings, including the Assisi hospital, and retaining structures, since the 1970s.
Hilly or mountainous landscape with large open valleys and intra mountain basins drained by the Tiber River and its tributaries.
Shallow and deep-seated, rapid to slow moving landslides, in urban and suburban areas. Ground subsidence caused by over-exploitation of confined and unconfined aquifers.