The Temple B in Pietrabbondante (Isernia, Italy) as a Case Study of Seismic Shield Properties of Roman-Italic Temple Foundations and Podiums

The Roman-Italic temples of central Italy, located along the Apennine ridge, an area of high seismic risk, have often been damaged by earthquakes and then reconstructed, as reported even in ancient sources. The Roman religious tradition prescribed that the temples be elevated on a podium, that acts as a sacred space, as the foundation, and as an architecturally defined above-the-ground element. Utilizing a multidisciplinary approach that combines a deep archaeological and architectural knowledge of ancient constructions with expertise in seismic engineering and the analysis of mechanical wave propagation, the contribution illustrates the current results on the ‘seismic shield’ of a selected case study, the Temple B of Pietrabbondante, whose foundation’s walls shape cellular compartments filled by layers of clay coming from the surrounding area. A three-dimensional, multiphysics, finite element, numerical model—taking into account either the geometry and the material of the foundations or the mechanical features of the soil between foundation walls—permits the simulation of the propagation of seismic waves towards the construction and the analysis of their impact on the foundation system. Underlying this working hypothesis is a recent field of research concerning ‘seismic metamaterials’, i.e. the introduction into foundation soils of suitable elements capable of deviating seismic waves, thus protecting constructions from earthquakes. The ‘seismic shield’ effect mostly depends on the geometric arrangement of the artificial aspects introduced into the soil: this led to thinking that colossal buildings, such as amphitheatres, have survived several seismic events over the centuries due to the particular cellular morphology of the foundations. It is a fascinating hypothesis, opening the way to new interpretations of the capacity of ancient monumental buildings to withstand earthquakes.