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Abstract. Shallow slopes in clayey colluvial covers are often involved in progressive downhill motion with discontinuous rate of movements, depending on fluctuations in pore-water pressure.In geotechnical engineering research on natural slopes, the main efforts have been concentrated on stability analysis, always with a rigid perfectly plastic body assumption. In case of slow slope movements, however, the notion of stability losses its sense, so the main question is not to evaluate a stability factor, but to model a velocity field and to define the kinematic and dynamic features of the movement (mobility analysis).Many authors, in their researches, deal with slow slope movements and for the complexity of the problem and the great number of parameters involved they agree about applying numerical techniques (FEM, FDM) and advanced material modelling (elastoviscoplasticity) and suggest to calibrate the involved parameters values with the help of "back analyses" of existing case histories.In this paper a mathematical model predicting the landslide body viscous deformations, is presented. The model has been implemented in a computer FDM code, and has been tested on some well known case histories. Here it is applied to the case of a landslide occurred at Gagliano Castelferrato (Sicily -Italy), where a great number of field measurements was available.

In every urbanized area, lifelines and essential facilities play a very important role and they become essential after natural disasters, such as earthquakes, floods, landslides and so on. The purpose of this research is to develop a working tool to assess lifeline seismic risk, overlaying information about the studied area's seismic hazard (referring to a seismic scenario) and lifelines that could expect damage. In damage models parameters are required, some representing pipes, others representing the soil behaviour and finally, at the very least a synthetic parameter representing the seismic hazard of the studied area (PGA, PGV or PGD). The evaluation of the network intrinsic vulnerability will be done in terms of a synthetic parameter called the Repair Rate. PGDs will be evaluated referring to attenuation laws and to earthquake induced slope displacements according to the Newmark approach. An application of the proposed model, developed by GIS techniques, will be applied to the case of a Sicily (Italy) important water network.

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In Italy, many urban areas suffer geotechnical hazard problems. However the Municipalities are not yet organised either to deal with the consequences of the possible phenomena, or to plan risk factor mitigation actions, by vulnerability reduction of the exposed elements.