Acoustic emission monitoring of Italian historical buildings and the case study of the Athena temple in Syracuse

Historical buildings often show diffused crack patterns due to different causes in relation to original function, construction technique and loading history. Non-destructive testing methods applied as in situ monitoring systems allow reliable evaluation of the state of conservation of these structures and its evolution in time. At first, in this paper different case studies are briefly presented to show the acoustic emission (AE) technique capability on damage evolution assessment in ancient brick and stone artworks, and to understand the most probable cause of evolving damage. Therefore, the specific case of the Syracuse Athena Temple, located in Sicily (Italy), is shown in detail. In this study, the AE technique was used to assess the evolution of damage in a pillar, which is part of the vertical load-bearing structure. By applying the AE source localization method, it proved possible to identify the microcrack initiation points inside the pillar, showing the presence of a damaging phenomenon that is evolving slowly but progressively. Finally, considering the AE data and the seismic records in a ray of 50 km from the Syracuse Athena Temple, a strong correlation between AE and the sequence of nearby earthquakes has been observed. This suggests that AE structural monitoring coupled with the analysis of local earthquake activity can be a tool of crucial importance in earthquake damage mitigation.