Earthquakes: Impact of shocks on buildings strongly reduced, also thanks to protection criteria from the past

Seismic action reduced by over 80% thanks to highly deformable seismic isolation devices in the horizontal direction, which, inserted between the elevated part and the foundation of a building, allow to greatly attenuate the energy transmitted by the earthquake to the structure. "Seismic isolation is one of the most advanced technologies for earthquake protection and is applied to both new and existing buildings", Paolo Clemente, at the ENEA Laboratory of Seismic Engineering and Natural Risks Prevention, said on the occasion of an event organized with the INGV, CNR and the University of Molise on earthquake-proof technologies in the history of construction. “The insertion of these devices at the base - the researcher continued – isolates the structure, which is then capable of withstanding the seismic action without being damaged, guaranteeing operation even in the case of violent earthquakes,  without the need for repair interventions" .

In particular, ENEA and Polytechnic University of Turin have patented an innovative seismic isolation system that aims at preserving buildings of particular historical and artistic value. "This system allows to seismically isolate the structure below its foundations, without touching it. A particularly important feature – Clemente pointed out - that makes this technology suitable for protecting our cultural heritage from the disastrous effects of earthquakes ".

The idea of ​​allowing the building to move with respect to the ground had already been studied and applied in antiquity, as demonstrated by the ancient construction techniques which allowed us to create great works that have come to the present day.

In the work of Pliny the Elder 'Naturalis Historia', the Roman writer recounts that the temple of Diana at Ephesus (6th century bC) - one of the seven wonders of the ancient world - rested on a layer of clay mixed with coal and ash. In this way, during an earthquake, the seismic action was not transmitted entirely to the building, because the structure could undergo horizontal movements with respect to the ground. The same technique had also been applied in numerous Greek temples and in the Greek colonies of the Black Sea and Magna Graecia; the Doric temples of Paestum, for example, rest on a thin layer of sand that separates the foundation from the ground. Similar examples can be also found in Latin America, where complex structures, founded with this technique, have survived strong earthquakes over the centuries.

"Examples like this show that we have a lot to learn from the study of the techniques of the past, whose principles are more easily applicable today thanks to modern technologies", Clemente concluded.