Geo-structural and spatial analysis on virtual outcrops for the characterization of rockslides triggered by Central Italy seismic sequence

Abstract

<p>High-magnitude earthquakes can trigger several landslides, especially in areas close to ridges and crests, where seismic ground accelerations are amplified. Such an effect was particularly evident during the long-lasting earthquake sequence of Central Italy (2016-2017), which triggered more than 1300 landslides, mainly rock slides and falls. Recent advances in 3D modelling techniques based on low-cost sensors, coupled with advances in geological and spatial analyses of 3D models, provided new opportunities to investigate such phenomena. In this study, we coupled detailed field data and up-to-date cm-scale resolution virtual outcrop models (VOMs), derived from Unmanned Aerial Vehicle (UAV) imagery, to analyse some rockfall and slides in the epicentral area of the Central Italy seismic sequence. Geostructural analyses on VOMs allowed defining the main joint orientations causing rock failures. High-resolution data also allowed to define volumes, extents of propagation areas and the topography of the failed slopes. These geometrical data together with strength parameters and assuming PGA at the sites, permitted to back-analyze both the triggering and the propagation of selected rockslides events. The results highlighted the effect of topographic amplification and complex dynamics of propagation due to rock fragmentation and debris remobilisation.</p>