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Francesco Faccini, University of Genoa (Italy)
Mauro Piccazzo, University of Genoa (Italy)
Andrea Robbiano, Consultant geologist (Ph.D.) (Italy)
Alessandro Tomaselli, Province of Genoa (Ph.D.) (Italy)
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This work is a scientific contribution aiming at identifying the DSGSD, which have been accurately investigated only over the last couple of decades, and to manage them according to their geomorphological hazard. Campegli hamlet was built over large landslides as well as the majority of settlements in Liguria; these mass movements were probably triggered during lastly Pleistocene following climate changes which fuelled conditions of geomorphological instability. The area features, as well as covers related to mass movements, ophiolites outcrops belonging to the Internal Ligurides. The tectonic profile shows a series of faults lineaments, which can be ascribed to the main direction N-S along which the hydrographical network settled and also ascribed to the second direction NO-SE where the valley established. The work was first carried out through references research regarding both scientific papers and studies related to land planning, secondly through a field survey, supported by photo interpretation analysis of the built-up areas and of a relevant neighbourhood of the landslide bodies, including secondary watershed ridges. Available cartographies of different times, since the end of the XVIII century to date, were compared. In the area drill surveys, by means of piezometers and inclinometers, geophysical prospecting, laboratory and in situ geotechnical tests were carried out.
Geotechnical and hydrological monitoring data, based on instruments reading over twenty years, were compared with available targets detected by radar interferometry. The last method aspect involves the inventory of the damaged artefacts of the built-up areas with the purpose of identifying possible correlations between current kinematic mechanisms and implications on buildings. The settlements of Campegli were built over landslides which can be ascribed to a DSGSD movement. Going from the ridge toward the valley, various slope failures are observed: they show clear counterslopes representing the top sector of a series of rock blocks, which locally developed into more recent landslides. Larger trenches were filled up by lacustrine deposits. With reference to the landslides classifications this phenomenon appears to be similar to the rock flow type. Data obtained by inclinometer cases show a good matching with the targets detected on the earth surface carried out by satellites and with the situation derived from the survey of all damage involving man-made structures: deformations are observed in the Case Il Lago slope sector, whereas the remaining sectors do not show important ongoing movements.
The measured total displacements which are included in a typical kinematic mechanism that can be ascribed to extremely slow movements ? goes from a few mm/y to 30 mm/y.
The whole monitored slope features a water table varies 2 to 10 m from ground level: year variations are even lower than 1 m consequently deep source mechanisms can be suggested without a clear correlation with rainfall.
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