GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 3.1 GNGTS 2024 UAS photogrammetry analysis for coastal hazard assessment: the case study of Maront landslide (Ischia, 2022) N.A. Famigliet 1 , A. Memmolo 1 , P. Miele 1 , E. Marota 2 , P. Belviso 2 , G. Avvisat 2 , C. Grasso 1 , R. Moschillo 1 , A. Vicari 1 1 Isttuto Nazionale di Geofsica e Vulcanologia- Sezione Irpinia, Italy 2 Isttuto Nazionale di Geofsica e Vulcanologia- Osservatorio Vesuviano, Italy Contnental and marine processes drive coastal areas’ landscape changes. The morphoevoluton results from both rapid catastrophic events and slower contnuous processes such as landslides, storms, and coastal land use, infuenced by sea actons. The clif erosion rates are linked to geological features, including rock mass strength and fracture system propertes. The assessment of erosion processes and quantfcaton of coastal retreat are crucial for efectve coastal planning and engineering mitgaton (Callaghan et al., 2009). Various methods, including geological processes monitoring, are used to assess coastal hazards (Quesada-Román and Peralta-Reyes, 2023). The present study focuses on Maront Bay's coastal evoluton on Ischia Island, which has historically been afected by slope stability issues due to volcanic actvity, earthquakes, and coastal erosion (Del Prete and Mele, 1999). In this perspectve, researchers of the INGV (Isttuto Nazionale di Geofsica e Vulcanologia) carry out periodical surveys of the Ischia territory. Drone surveys were used to evaluate the diference between pre- and post-landslide Digital Surface Models (DSMs) to focus on the November 26th, 2022 landslide event (Figure 1b). That event afected the volcanic clif and can be classifed as debris avalanche (Hungr et al., 2014) causing severe problems to the nearby structures and a remarkable scarp retreat of about 20 m. Consequently, debris and large blocks with the creaton of a depositon area invaded the beach. The pre (acquired on December 15th, 2021) and the post (acquired on January 31, 2023) datasets have been orthorectfed and georeferred with PPK (Post Processing Kinematc) workfow (Famigliet et al., 2021) using as GNSS base the staton SANT (Santantuono) managed by INGV and located onto the Ischia island. Thanks to very high spatal resoluton of products (1.7 cm) this analysis estmates mobilized volumes (Figure 1c) allowing the comparison with results presented by other authors (Massaro et al., 2023). The adopted approach ofers a geometric understanding of coastal clif evoluton afer the landslide impact. These insights are crucial for managing landslide risks on Ischia and for other similar environments, guiding the development of mitgaton strategies to protect the environment and ensure residents' and visitors' safety.