Instability phenomena affecting the cultural heritage cave of Antro della Sibilla (Cuma, Italy)

The present work aims at the analysis of localized instability phenomena affecting the archaeological site of the Sibilla Antro. The cave was excavated by Greek colonists in the formation of Neapolitan Yellow Tuff, a pyroclastic weak rock. This rock is naturally fractured and weakly stratified: for these reasons local instability phenomena occurred along the whole extent of the Antro, worsened by the deterioration of past remediation interventions by passive dowels in the 1980s. Based on a geomechanical field survey and a laboratory characterization of the rock material, a 2D numerical model of the most threatened section was implemented to assess the stress concentration points and the current stability conditions. A proposal is also made for possible low impact measures for safeguard and conservation purposes.