Submarine slides off posillipo hill (Naples, Italy)

The interpretation of Side Scan Sonar images and Subbottom profiles along the Neapolitan coast, proves the existence of submarine slide deposits at the foot of a subaerial cliff. The cliff is cut into volcanic deposits of Neapolitan Yellow Tuff (12 ka BP) and is presently affected by rock fall. The sonographs are free from scale distortions, and tonal and textural patterns indicate considerable topographic and sedimentologic variety. The submarine slide overlies the Neapolitan Yellow Tuff (12 ka BP). Three distinct areas can be recognized: i) a proximal area composed of volcanic, blocky, debris flow deposits, ii) a central area composed of highly porous pebbly sand deposits, iii) a distal area composed of silt sediments. The slide extends for 700 m terminating against a bathymetric barrier created by a tectonic deformation area. A fossil beach is found seaward of the deformation area and formed during the post 12 ka sea level rise. The presence of an evolving slide close to the coast of a densely populated city like Naples is of great significance for regional planning and engineering projects due to the potential instability of the area.