Multitemporal Landslide Mapping and Quantification of Mass Movement in Red Beach, Santorini Island Using Lidar and UAV Platform

Santorini Island constitutes one of most unique geological structures as it compromises a distinctive Miocene volcano. Rockfalls and landslides are widespread phenomena in Santorini due to orientation and steepness of the cliffs which are mainly formed as high elevated lava domes with loose material inside, extruded by sticky, slow-flowing dacite lava. Especially, landslide events in high vulnerable areas can cause significant environmental and socioeconomic impacts. Following a landslide hazard, comprehensive and reliable information on the geotechnical and geometric properties but also on the actual consequences of the phenomenon is mandatory. Today, the evolution of geoscience enables the use of innovative tools such as Unmanned Aerial Vehicles (UAVs) to address emergency response in disastrous situations. As a result, landslide identification and monitoring of large areas can be accomplished economically and timely. During the last decade, the UAV platform has become a useful and reliable research tool in emergency situations such as landslide monitoring. The current research performs a semi-automated method to evaluate and quantify site-specific landslide hazard in the area of Red Beach on the island of Santorini, Greece. Red Beach shows very high tourist activity during the whole year, so it is mandatory for safety reasons to establish guidance to eliminate landslide hazard in prone areas. Considering the availability of high spatial and spectral datasets, multitemporal change detection techniques were performed between two different datasets acquired in February and September of 2017 with a UAV platform. The methodology implemented in the current research revealed the accumulation area of failure, flow direction but also allowed the quantification of the mass movement in the area of interest. The outcome of the current research aims to highlight the usefulness of photogrammetry and UAV platforms to assess and mitigate the potential negative consequences of landslide hazard.