Landslide susceptibility assessment by thermal surveys: case studies from southern Italy

Landslide susceptibility analysis is a critical aspect of slope hazard assessment, requiring the understanding of the complex interactions between slope and atmosphere, in terms of geological, geotechnical and climatic factors. This study focuses on the evaluation of landslide susceptibility in Southern Italy, encompassing both rockfall events occurring along rocky cliffs in Melendugno (Adriatic coast, Apulia region) and a large earthflow mass in the Southern Apennines, respectively. In particular, this study is aimed at presenting preliminary results arising from advanced field digital surveys performed in the study areas. High-resolution thermal (7 cm) and RGB (3 cm) digital images were captured using a UAV-mounted camera during a survey conducted in July. Data processing and analysis were carried out using DJI thermal analysis tools, Agisoft Metashape and GIS software. The thermal surveys provided valuable insights into surface temperature variations within the study areas, in terms of thermal anomalies, which could potentially represent indicators of instability phenomena. Along the Melendugno rock cliff, low-temperature anomalies highlighted fractures and openings between calcarenite layers, while high-temperature zones are supposed to indicate weathered and degraded rock surfaces. As regards the Montaguto landslide, high-temperature regions indicate active fractures, whereas low-temperature areas correspond to water accumulation, potentially exacerbating slope instability. The temperature data obtained from the thermal surveys have been also validated through temperature and climatic data acquired via weather stations installed in the study areas. Future work will involve the collection of temporal data for creating multi-temporal maps and the application of numerical models to simulate the slope stress-strain response under varying environmental conditions.  Combining thermal data and computational modelling, the study is aimed at providing critical insights into slope surface conditions and material degradation, enhancing stability analyses and aiding risk mitigation strategies. The findings are intended to underline the potential of thermal surveys in assessing landslide dynamics and advancing geohazard management.