Roberto Francese

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.

Hydrodynamics in evaporate-bearing fine-grained successions investigated through an interdisciplinary approach : A test study in southern Italy-hydrogeological behaviour of heterogeneous low-permeability media

Messinian evaporates are widely distributed in the Mediterranean Sea as outcropping sediments in small marginal basins and in marine cores. Progressive filling of subbasins led to the formation of complex aquifer systems in different regions where hypersaline and fresh water coexist and interact in different manner. It also generates a significant diversification of groundwater hydrochemical signature and different microbial communities. In the case study, the hydrogeology and hydrochemistry of the whole system are influenced by good hydraulic connection between the shallower pyroclastic horizon and the underlying evaporate-bearing fine-grained Messinian succession. This is demonstrated by the merge of hydrogeological, chemical, isotopic, and microbiological data. No mixing with deep ascending waters has been observed. As shown by geophysical, hydraulic, and microbiological investigations, the hydraulic heterogeneity of the Messinian bedrock, mainly due to karstified evaporitic interstrata/lenses, causes the hydraulic head to significantly vary with depth. Somewhere, the head increases with the depth’s increase and artesian flow conditions are locally observed. Moreover, the metagenomic investigations demonstrated the existence of a poor hydraulic connection within the evaporate-bearing fine-grained succession at metric and decametric scales, therefore leading to a patchwork of geochemical (and microbiological) subenvironments.

Joint Modelling and Monitoring on Case Pennetta and Case Costa Active Landslides System Using Electrical Resistivity Tomography and Geotechnical Data

The aim of this paper is to study the Case Costa and Case Pennetta active landslides complex in the Northern Apennines (Parma, Italy). A ground model of an active and complex landslide system in instability prone rocks, made mainly by sandstones and claystones (Scabiazza Sandstones, Ligurian Unit), is developed through an integrated approach, utilizing different monitoring tools. Some of the tools are traditional (i.e. piezometers and inclinometers) and others are innovative, such as the acquisition of electrical tomographic data in time-lapse mode (TL-ERT). The latter has many practical applications to the study of subsurface properties and processes. This approach will allow to create a model of the physical state of the complex landslides, to observe the groundwater circulation and its variation with time, by relating it to the kinematics of the landslide bodies. Results of the landslide investigation revealed that an integrated approach, centred on volumetric geophysical imaging, successfully achieves a detailed understanding of structure and lithology of a complex landslide system, which cannot be attained through the use of remotely sensed data or discrete intrusive sampling alone. This paper describes this multi-technique approach for landslide hazard assessment reporting the preliminary monitoring results; such approach seems to be applicable to other hazardous earthworks and natural slopes.