Uncovering the traces of unknown earthquakes at Segesta (NW Sicily, Italy): insights from multidisciplinary investigations

Abstract

The transformation of Segesta, from the Hellenistic period (sixth century BCE) to the early Middle Ages (fifth–sixth century CE), has been extensively studied by archaeologists and historians. While social and political changes were the main drivers of urban evolution, practices such as abandonment, spoliation, and building transformations increased buildings’ structural vulnerability, making them more prone to seismic damage. Although historical sources from the Roman period do not mention any earthquakes affecting Segesta, recent archaeological investigations have revealed collapsed layers in the Agora and Mango Sanctuary, and structural deformations in the Theater and Doric Temple. Furthermore, architectural analysis indicates the use of anti-seismic construction techniques in at least two structures on the site. Through multidisciplinary archaeoseismological investigations, this study aims to: (i) provide evidence of past earthquakes based on recent excavations literature review, and on-site observations; (ii) explain, through local site-effects, the selective collapse observed in the Agora and Mango Sanctuary, as well as the deformations at the Theater and Doric Temple; and (iii) analyze the seismotectonic framework of the potential seismic sources. To achieve these objectives, the study combines architectural damage surveys, stratigraphic analysis, drone-based photogrammetry, and non-invasive geophysical prospection (HVSR and MASW). This integrated approach enables a quantitative reconstruction of the local seismic response and deformation patterns across the site, while supporting a replicable framework for investigating ancient seismicity in similarly complex archaeological landscapes. These findings highlight a previously unrecognized gap in the seismic history of this low tectonic strain rate region, pointing to the occurrence of significant past earthquakes that are absent from historical records and current seismic catalogs—which, for this area, list only the 1968 Belice Valley sequence. Therefore, this study contributes essential input data for refining the seismic hazard and enhances our understanding of the historical seismicity and regional seismic risk.