Earthquake-Triggered Landslides and Slope-Seismic Waves Interaction Inferring Induced Displacements

Earthquake-induced landslide mass mobility is a topic of particular relevance for the analysis of earthquake-induced ground effects scenarios. The landslide masses already existing on the slopes interact with the seismic waves that propagate from the bedrock, giving rise to effects of amplification of the seismic motion at specific frequencies connected to their geometry and their dynamic properties. The quantification of the earthquake-induced displacements expected in landslide masses through numerical models under dynamic conditions highlights how, especially for medium-low energy levels of the seismic input, the displacements thus obtained are generally higher than those computed by conventional approaches (e.g. Newmark method applied to the hypothesis of rigid or deformable block and related semiempirical relations). A series of case studies has also proved that the geometry of significantly dislodged landslide masses (i.e. segmented into kinematically distinct portions, namely “blocks”) due to their geomorphological evolution over time, significantly controls the seismic-induced displacements obtained by numerical models. In particular, the results highlight that the maximum displacements computed through the numerical models do not correspond to seismic inputs whose characteristic periods coincide to those of the resonance or of the length of the landslide mass but are more directly connected to the smaller dimensions of the individual blocks in which the landslide mass is segmented.