Topographic Effects Evaluation of Landslides in a Tyrrhenian Area of Southern Italy

The Caronia landslides area is located in the Tyrrhenian northeastern sector of Sicily (Italy). Starting from 2010, the attention has focused on the study of landslides phenomena occurred in this area, which caused significant economic damage to buildings and infrastructures and loss of productive activities. The Caronia area is characterized by geotechnical, geological and morphological heterogeneity and for this reason the site is particularly prone to seismic topographic amplification effects. In this paper, authors carried out a numerical study focused on the topographic seismic effects evaluation, concerning the slope affected by landslides phenomena starting from 2010. For this site the geotechnical and geological characterization is available, with reference to both in-situ and laboratory tests; boreholes, piezometers, Down-Hole tests, MASW tests, seismic tomographies and inclinometer measurements have been carried out. 1-D and 2-D local seismic response analyses have been carried out by using different synthetic seismograms related to the Scenario Earthquake of Messina and Reggio Calabria of December 28, 1908. The results of the numerical analyses have been presented as comparisons in terms of response spectra and response seismograms at the surface. The topographic effects using the Ashford & Sitar (1994) approach have been also evaluated. This study demonstrated that gently undulating regions could produce unexpectedly large and frequent landslides when struck by severe earthquakes, and when soil layers vulnerable to ground shaking cover the ground.