An interdisciplinary study of the Pietra Maura earthflow in the Marsico Nuovo territory (Southern Italy)

Landslides are a significant geomorphological factor in the natural evolution of the Southern Apennines slopes (South Italy), with earthflows being one of the most representative types. The development of large earthflows in this region is primarily due to extensive clay-rich outcrops, whose activation was facilitated by warm, humid Holocene climates. These earthflows can be very extensive, often affecting entire slopes and exhibiting numerous minor reactivations over time. This study focuses on the Pietra Maura earthflow in the Marsico Nuovo Municipality (Basilicata Region), integrating detailed geological and geomorphological investigations with geophysical techniques to characterise and better understand its evolution. The landslide extends approximately 4.2 km NW-SE, with an average width of 900 m, and affects the area below the maximum level of the Marsico Nuovo dam and two urban zones, crossing roads, power lines, and aqueducts, necessitating ongoing monitoring to prevent damage. To better understand the extent and dynamics of the Pietra Maura earthflow, a detailed geological and geomorphological survey was conducted, supported by advanced geophysical techniques, such as Interferometric Synthetic Aperture Radar (InSAR) and Electrical Resistivity Tomography (ERT). InSAR data from Copernicus Sentinel-1 satellites revealed detailed east-west ground deformation patterns, while ERT helped reconstruct the earthflow’s geometry, showing a variable thickness of up to 50–60 m and identifying sectors with high-water content. The findings provide essential insights for taking appropriate actions to stabilise the landslide and improve area management.