Giacomo Alfredo D'amato Avanzi

Shallow Landslides Triggered by the 25 October 2011 Extreme Rainfall in Eastern Liguria (Italy)

A very heavy rainstorm hit Eastern Liguria (Vara Valley and Cinque Terre area) and North-western Tuscany (Magra Valley) on 25 October 2011. This event produced floods and hundreds of shallow landslides, causing 13 casualties and severe damage to villages, infrastructures and roads. In the Vara Valley the Brugnato rain gauge recorded 468.8 mm in 6 h, with a maximum rainfall intensity of 143.4 mm/h. A landslide inventory map was carried out, together with a database including the main features of the source areas. At present, the database is complete for the Pogliaschina Torrent basin (Vara Valley), where at least 658 shallow landslides (mainly soil slip-debris flows and debris flows) were triggered. The shallow landslides induced by the 25 October 2011 event were analysed, together with geological, geomorphological and land use features of their source areas, with the aim of identifying common triggering conditions. This paper shows preliminary results of the comparison between the landslide inventory and the main slope features of the Pogliaschina Torrent basin.

DP Test in Geotechnical Characterization of Shallow Landslides Source Area: Results and Perspectives

Aiming at improving the knowledge on the source areas of shallow landslides, this research deals with the geotechnical characterization of the debris slope cover of arenaceous formations, by means of low cost dynamic penetration tests (Dynamic Probing – DP).

Processi gravitativi di instabilità in rocce molto fratturate: il metodo alle differenze finite in un caso applicativo nella provincia della Spezia

The Marinasco-Strà village is involved in wide instability phenomena in rock masses, determining a high landslide risk. In this area a geological-technical, kinematic and geomechanical characterization of the landslides and rock masses was carried out. Moreover, a monitoring system concurred in collecting important data on rainfall, piezometric response and deformation of the slopes. This integrated approach allowed the realization of a model of the landslide mass, regarded as a multiphase system and based on the physical-mechanical characterization of soil and rock. The determination of the state of stress and deformation and the location of actual or possible zones of failure inside the slope were among the main aims. In particular, the finite-difference method was applied, in order to estimate the stressstrain response of the slope to the variations of tensional state; in fact, this method fits better the instability phenomena in intensely fractured rock masses. A deformation model, consistent with the results of the investigations, was performed. In the analysed model, the shear strain concentrates along the main discontinuities deriving from plastic deformation of the mass causing the slope failure. Key terms: landslide, DGSD, numerical modelling, La Spezia, northern Apennine Termini chiave: frana, DGPV, modellazione numerica, La Spezia, Appennino Settentrionale