Living and building on an active seismic fault: the case of Hierapolis of Phrygia (Turkey) between the late Hellenistic age and the early-Byzantine period

The paper focuses on the results of geo-archaeological investigations carried out in Hierapolis of Phrygia (Turkey) between 2013 and 2018. The integration of archaeological excavations, geophysical prospections and diagnostic investigations with a thermal infrared camera allowed acquiring new data on the surface manifestations of the seismic fault that crosses the site, such as cracks in the first substrate, sinkholes, and underground cavities. The research highlighted the close relationship between the effects produced on the surface by the fault and the ritual practices in the two sacred areas in the centre of the city, namely the Sanctuary of Apollo and the Sanctuary of Hades. This investigation also allowed for an examination of the building solutions adopted within the two sanctuaries to adapt the edifice built in the late Hellenistic and Imperial era to the peculiar tectonic manifestations and exploit the hydrogeological resources connected with them.