Claudio Tellini

A procedure for landslide susceptibility zonation by the conditional analysis method

Numerous methods have been proposed for landslide probability zonation of the landscape by means of a Geographic Information System (GIS). Among the multivariate methods, i.e. those methods which simultaneously take into account all the factors contributing to instability, the Conditional Analysis method applied to a subdivision of the territory into Unique Condition Units is particularly straightforward from a conceptual point of view and particularly suited to the use of a GIS. In fact, working on the principle that future landslides are more likely to occur under those conditions which led to past instability, landslide susceptibility is defined by computing the landslide density in correspondence with different combinations of instability factors. The conceptual simplicity of this method, however, does not necessarily imply that it is simple to implement, especially as it requires rather complex operations and a high number of GIS commands. Moreover, there is the possibility that, in order to achieve satisfactory results, the procedure has to be repeated a few times changing the factors or modifying the class subdivision. To solve this problem, we created a shell program which, by combining the shell commands, the GIS Geographical Research Analysis Support System (GRASS) commands and the gawk language commands, carries out the whole procedure automatically. This makes the construction of a Landslide Susceptibility Map easy and fast for large areas too, and even when a high spatial resolution is adopted, as shown by application of the procedure to the Parma River basin, in the Italian Northern Apennines.

Large-scale geomorphological mapping as a tool to detect structural features: the case of Mt. Prinzera ophiolite rock mass (Northern Apennines, Italy)

ABSTRACT This paper presents a geomorphologic map of the Mt. Prinzera ultramafic rock complex (Parma Province, Emilia-Romagna Region, Italy) mapped at large scale (1:2500). The map is the first contribution to the detailed geomorphologic knowledge of the area within the framework of a multidisciplinary approach used to analyse Mt. Prinzera as a hard rock aquifer case study. The geomorphologic mapping was carried out by field survey and aerial photograph analysis. All the surface processes and landforms were considered, with particular attention to structural geomorphologic features. The mapping of linear morphologic features was considered useful for revealing the presence of sets of joints otherwise difficult to detect due to surface weathering. Sets of rock discontinuities are important for water seepage and percolation and their identification is crucial for developing the hydrogeological conceptual model of the aquifer.

Fingerprints of Large-Scale Landslides in the Landscape of the Emilia Apennines

Impressive depletion and accumulation landforms created by the millennial evolution of large-scale landslides are distinctive features of the landscape of the Emilia Apennines (Northern Italy). They are complex earth slides and earth flows that can be tens of hectares wide and can involve millions of cubic metres of clayey deposits originated by the failure and weathering of weak rocks such as clayey flysch and melanges. These landslides have originated in large number since the upper Pleistocene. It is estimated that they now cover up to 20% of the mountain areas of the region. They typically alternate periods of dormancy that can be centuries long, to periods of reactivation that can last for a single season or several years. Upon reactivation, they rejuvenate landforms that outstand impressively from the surrounding landscape and cause severe damages to infrastructures. The chapter presents some relevant examples of these landslides and related hazard and risk issues.

The Geomorphologic Survey as Tool to Support Risk Management After Landslide Reactivation: The Case Study of Sauna di Corniglio Landslide (Northern Apennines, Italy)

During the period winter–spring 2012–2013, abundant rainfalls occurred in the area between Parma and Enza streams. In the first half of April 2013, the reactivation of a complex landslide involving a portion of the Sauna village (T Parma valley) occurred. Soon after the first rotational slide, the depleted mass started to move as a flow, progressively involving the western part of the settlement, destroying three houses, one cattleshed and many rural buildings. This paper reports the results of the geomorphologic survey performed in the days soon after the landslide reactivation. It has been aimed to describe the geomorphologic features of the landslide to support the risk management and mitigation.

Tectonics and Large Landslides in the Northern Apennines (Italy)

This work was aimed to highlight the spatial relationships between large-scale gravitational phenomena and tectonic uplifted structures in the area between Enza river valley and Taro river valley in the Northern Apennines. The structural-tectonic map of the investigated area and the inventory map of the large landslides and DSGSDs were made. The analysis of the structural map highlighted the existence of antiforms with axes roughly SE-NW. The comparison between the large landslides and the antiforms has shown that a spatial relationship between large complex landslides (earth/rock slides – earth flows) and positive geological structures exists.

Landslides types controlled by tectonics-induced evolution of valley slopes (Northern Apennines, Italy)

This paper investigates the role played by geomorphological and tectonic processes affecting a portion of an active mountain belt in causing the occurrence of different types of landslides developed in flysch bedrock. The adopted multidisciplinary approach (geomorphology, geology and geophysics) allowed to recognize in a portion of the Northern Apennines of Italy different types of landslides that developed in response to slope dynamics, in turn dependent on broader regional-scale tectonic processes. Sedimentary bed attitude, local tectonic discontinuities and lithology only partially influenced the type of landslides, which have been deeply affected by the activity of regional-scale antiform that controlled the hillslope geomorphic evolution in different ways. The growth of this structure and the tilting of its forelimb produced gently dipping slopes that approached the threshold angle that can cause the occurrence of (mainly) translational rockslides. Conversely, high-angle normal faulting parallel to the antiform axis (related to a later stage of activity of the antiform itself) strongly controlled the stream network evolution and caused the watercourses to deeply incise portions of their valleys. This incision produced younger steep valley slopes and caused the development of complex landslides (roto-translational slides-earth/debris flow). The results of the integrated study presented in this paper allowed to distinguish two main types of landslides whose development reflects the events that led to the geomorphological and geological evolution of the area. In this perspective, within the study area, landslides can be regarded and used as indicators of broader-scale recent tectonic processes.