Caratterizzazione geotecnica e modellazione numerica ad elementi distinti dei depositi della Sciara del Fuoco (Stromboli, Italia)

The Stromboli island is one of the most active volcanoes in the world. Its structural evolution has been characterized by four large sector collapses affecting the NW flank, resulting in the creation of the Sciara del Fuoco horseshoe-shaped depression. In this study the local and general stability of the Sciara del Fuoco recent volcanic debris has been analysed. These loose deposits represent a potential unstable mass that can be mobilized evolving in granular flow running along the Sciara del Fuoco into the sea, eventually forming tsunami waves as in the latest landslide events of December 2002 and January 2003. The paper presents the first achievements toward the stability analysis of volcanic debris via numerical modeling according to the following steps: 1) geotechnical characterization of materials 2) calibration of the numerical model based on experimental geotechnical data. A set of biaxial tests has been simulated by numerical modelling and compared with the experimental triaxial compression tests. The sensitivity analysis has been focused on finding the particle mechanical parameters that better represent the rheology of the volcanic debris at the macroscopic scale. Specific mathematical relations between mechanical parameters of single particles and particles assembly have been found as a function of the acting stress state. These relations represent the first goal in determining the actual rheology of granular materials and in evaluating its influence on slope dynamics by performing particle based numerical modelling.