Seismic stability of the excavation fronts in the ancient Roman city of Pompeii

The paper deals with the problem of the seismic stability of excavation fronts in the ancient Roman city of Pompeii, a famous UNESCO World heritage site near Napoli, Italy, buried under 4–6 m of volcanic ashes and pumices during the eruption of Mount Vesuvius in 79 AD. The attention is focused on the Insula dei Casti Amanti, a block of masonry buildings in the city centre partly excavated in recent years. Ground motion recorded on outcropping rock compatible with the seismo-tectonic background and the spectrum specified by the Italian code for the life-safety limit state criteria were used for wave propagation analysis. Both 1-D and 2-D Seismic Response Analyses were carried out to identify both surface (topographic) and valley (morphology) effects. This study allowed to quantify in a detailed manner the seismic demand in the excavation fronts. Re-profiling interventions based on the classical pseudo-static approach would be too invasive for the archaeological site. On the contrary, the alternative Newmark-type approach, based on the evaluation of the permanent rotations of the potentially unstable soil mass, is much more appropriate for a sustainable definition of slope stabilising interventions.