The Monitoring of the Temple of Athena in Paestum (Southern Italy)
The need to preserve ancient monumental architecture finds crucial support in innovative methods and technologies that can improve our understanding of the buildings’ structural health, promoting proactive maintenance. In this context, the Archaeological Park of Paestum & Velia and the Department of Civil Engineering of the University of Salerno had already implemented several monitoring strategies for the preservation and the proactive maintenance of the heritage, such as the Temples of Neptune and Athena.
The temple of Athena has been subject to various maintenance interventions over the last century. The most significant of these was made in the 1960s on the structural elements of the east façade of the temple, when iron bars were inserted along the columns and architrave, in order to connect the several stone blocks together [1,2].
After this intervention, in 1972 the EST façade of the temple was struck by a thunderbolt with the subsequent formation of an important crack pattern and the partial destruction of the first drum of the fourth column. The presence of the iron bars determined the orientation of the electric discharge up to the base block, with its consequent partial explosion. After the event of 1972, the damaged drum was subjected to an important restoration activity. In fact, the current configuration of the column is the result of a restoration of the block through the relocation of the destroyed parts.
In 2005, a notable crack pattern on the aforementioned column was detected. For this purpose, a monitoring activity was carried out from 2008 until 2010 by a team of the University of Naples – Federico II, to control the evolution of the crack pattern. The study highlighted that no substantial changes were detected during the observation period. However, in 2021, an evident evolution of the crack pattern was recognized.
This evolution showed the need to develop an ad-hoc monitoring plan to safeguard the temple. For this purpose, the Archaeological Park of Paestum & Velia with the Department of Civil Engineering of the University of Salerno started dedicated monitoring activities. These activities involve a direct periodic survey of the crack pattern on the block using very high-resolution orthophotos, as well as continuous monitoring of the colonnade of the east facade through sensors. The high-resolution photo allows to control the punctual evolution of the crack patterns, while the continuous monitoring enables the evaluation of possible evolution related to a global mechanism that involves the colonnade. The activities related to the monitoring network are carried out with the support of Leica Geosystems S.p.a.. The continuous monitoring network was installed in March 2023 and it is composed by wireless sensors called “Omni Tilt&Distance Node”. These types of devices are integrated sensors with the function of laser distance meters, 3D inclinometers and temperature sensors. The sensors are placed on the top of the column, on the abacus, with the laser pointed downwards, with the objective to monitor eventual relative displacement between the column and the stylobate, as well as tilt variation.
With respect to the heritage materials, sensors have been installed with a safety anchor on the protective covers of the capitals. In particular, the devices support bases were fixed onto the protective covers using mortar and mechanical plugs. The bases were then protected laterally with the same mortar, which included pigments to camouflage the support with the travertine.
REFERENCES
1. Cipriani M., 2007, “Dalle integrazioni lapidee del Bonucci alle imperniature metalliche della Fondedile. Gli interventi di Restauro dei Templi di Paestum tra il 1805 e il 1962”, in “Il restauro dei Templi di Poseidonia – Un intervento di conservazione e valorizzazione”, Proceedings of the international conference, Paestum 26-27 June 2004, Valerio Maioli S.p.A, Ravenna, Italy, pp. 13-34
2. Fondedile, 1973, “Restauro Statico di Monumenti”, pp.36-37