Structural Investigations and Modelling of Seismic Behaviour on Ruins in the Monumental Area of Hierapolis of Phrygia

The archaeological site of Hierapolis of Phrygia presents a number of ruins, which date back to the II century B.C. They are located in a medium-high seismic area crossed by a system of faults still active. The valorisation plan of the site aims at establishing an archaeo-seismological area, i.e., a site where tourists can visit structures keeping the signs of past earthquakes in proper safety conditions. To this purpose, the knowledge phase is a fundamental step in the preservation process. The paper presents the results of a series of investigation procedures applied to several incomplete structures still standing in the area, namely: the Martyrion of St. Philip, the tombs A18 and A20, and the monumental latrines. The geometrical survey and the elaboration of images were used in combination, as base for the evaluation of the conservation conditions, the interventions applied in the past, and the deterioration and damage states of the structures. To integrate the analysis, soil and structures were also inspected on site with NDT procedures. In particular, tests provided the seismic soil classification (by MASW, HVSR) and the qualification of masonry elements (by SPVT, GPR). Limit analysis and FEM approach were adopted to characterize the actual seismic behaviour of the structural assemblages and to predict their possible future damage. Results pointed out the high vulnerability of large portions of the structures still standing in the site.