Considerazioni preliminari sulla caratterizzazione di soil slip in alcune zone di studio della Stretta di Catanzaro (Calabria)

In a study area of Calabria multidisciplinary researches are in progress in order to test procedures devoted to define the geo-environmental contexts with homogeneous characteristics with respect to specific types of slope instability. In the study area, that falls inside a graben structure, sedimentary and metamorphic rocks crop out. Both rocks are affected by widespread slope instability, shallow and deep seated landslides, and erosion processes (from moderate to intense). The shallow failures in the slopes (from 0.5 to 2 m in depth) assume particular importance in the area. This type of instability, indicated as "soil slips", involves small volumes of soil and can produce serious damage to property and danger to people. The hazard that this type of instability represents is determined by their kinematic mechanism (slide and immediately subsequent rapid flow) and by their spreading during particularly severe rainstorms. The high incidence of such type of slope instability, has suggested a research aimed at defining a methodological approach to quickly identify their features. These features are essential for the development of forecasting models and subsequent definition of remedial measures, aimed at preventing or reducing risks. For this reason, in three sample zones of the study area where soil slips involving sedimentary terrains detailed geo-morphological reliefs and geotechical surveys have been carried out. This survey, analyzed together with the photographic documentation acquired during about ten years of observation, has produced a satisfactory definition of the geometric characteristics of the shallow failures. The knowledge of the dates of some mobilization occurred in the period considered and the rainfall time series, allowed to assess the characteristics of the triggering rainstorm events. Moreover, the results of some accurate topographic surveys carried out in order to obtain important information about the geometry of the slopes, are shown. Finally, the results of geotechnical tests enabled to define the particle size envelopes and the index properties of the soil covers involved in shallow instabilities.