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Two adjacent landslides affect the National Road 52 "Carnica" in the Tagliamento River valley, Carnian Alps (46°23'49" N, 12°42'51" E). The phenomena have been studied for more than a decade allowing a detailed geological and geomorphological reconstruction to be delineated. That was done on the ground of a large number of monitoring data collected during more than 10 years of investigations. Since the landslide are threatening an important road countermeasure works to ameliorate stability conditions of the slides need to be designed. The paper focuses on the creation of a numerical model capable to reconstruct the dynamic of both landslides and to be consistent with monitoring data. Two cross-sections, one for each landslide, have been selected for the analysis. The geometry of the slip surface was reconstructed on the basis of control points like the slip surface readings in inclinometers and on geomorphological evidence for the contour. The FLAC2D code is used to evaluate actual stability of these landslide. Results will be used to plan countermeasure works.

An active complex earth slide causes risk for the resort of Corvara in Badia (South Tyrol, Italy). Displacement rates measured in the source area from 2001 to 2004 by GPS and inclinometers ranged between mm and dm per month, with sliding depth varying from 20 to 40 m. In this crucial sector of the landslide a mitigation option is the construction of rows of wells coupled with pile-founded retaining structures. The effect of such countermeasures was estimated by finite difference method, using FLAC 2D programme. Elasto-visco-plastic behaviour along the sliding zone was simulated with Burger’s viscosity model. Plasticity and viscosity parameters were determined in back analysis by fitting computed and measured displacements in fully saturated conditions. Numerical simulation showed that lowering ground water level for several meters is not sufficient to significantly reduce movement rate and that retaining structures introduced into the model do not achieve a complete mitigation of movements, since parts of the slope far-off the structure keep moving.

This study involves the integration of multiple thematic datasets for landslide susceptibility assessment through spatial prediction models. The proposed methodology has been applied in the Bystrzanka-Biczyska area (Beskid Niski Mts., Carpathians Mts., Poland), characterised by a very high density of landslides. The susceptibility assessment has been based on an indirect bivariate statistical analysis ("Weights of Evidence" modelling technique, Bonham-Carter et al., 1989) performed in order to predict the occurrence of an event (landslide) where well-known evidences (predictor variables) are available. According to the relative importance of each evidence, a landslide susceptibility map has been produced. Observing final prediction results, it is concluded that the susceptibility map gives useful information both on present instability of the area and its possible future evolution in agreement with the morphological evolution of the area.

International audience; The Sauris reservoir is a hydroelectric basin closed downstream by a 136 m high, double arc concrete dam. The dam is firmly anchored to a consistent rock (Dolomia dello Schlern), but the Lower Triassic clayey formations, cropping out especially in the lower part of the slopes, have made the whole catchment basin increasingly prone to landslides. In recent years, the "La Maina landslide" has opened up several joints over a surface of about 100 000 m2, displacing about 1 500 000 m3 of material. Particular attention is now being given to the evolution of the instability area, as the reservoir is located at the foot of the landslide. Under the commission of the Regional Authority for Civil Protection a numerical modelling simulation in a pseudo-time condition of the slope was developed, in order to understand the risk for transport infrastructures, for some houses and for the reservoir and to take urgent mesaures to stabilize the slope. A monitoring system consisting of four inclinometers, three wire extensometers and ten GPS bench-mark pillars was immediately set up to check on surface and deep displacements. The data collected and the geological and geomorphological evidences was used to carry out a numerical simulation. The reliability of the results was checked by comparing the model with the morphological evidence of the movement. The mitigation measures were designed and realised following the indications provided by the model.

The Ca' Lita landslide is a large and deep-seated mass movement located in the northern Apennines, about 70 km west of Bologna (Northern Italy). It consists of a composite landslide that affects Cretaceous to Eocene flysch rock masses and chaotic complexes. Many of the sectors making up the landslide have resumed activity between 2002 and 2006, threatening some villages and an important road connecting several key industrial facilities located in the upper watershed. This paper presents the management of the emergency, dealing with the investigation campaigns (geological, geomorphological and LiDAR surveys, borehole drillings, seismic surveys), with the monitoring (in situ instrumentation) and with the design and construction of mitigation measures. The whole process, from landslide reactivation to date, has been modelled on a numerical basis with the finite difference code FLAC 2D, to assess the efficiency of the mitigation system and to propose further countermeasure works in different scenarios.