Site effects due to the presence of cavity near the cliffs

The paper reports a numerical evaluation of seismic site effects from an underground cavity in Sant’Agata de’ Goti, a typical medieval town of south Italy, perched on a tuff ridge. The cavity, located along the edge of Martorano ridge and interconnected to the historical center, was analyzed with the 2D FLAC code. A dynamic analysis was carried out with seven spectrum compatible accelerograms according to Italian code. In order to distinguish the site effects, the analysis was done with and without the cavity. From comparison of the two cases, expressed by maximum acceleration on the ground surface, it was observed that the presence of the cavity leads to higher acceleration towards the edge of the cliff with respect to a 1D analysis and to simplified procedures according to the Italian National code.