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Athens Acropolis has good seismic behaviour

30 November 2015 / 21:11:51  GRReporter
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"Monuments and other historical facilities in Greece need a better seismic protection," says director of the anti-seismic technology laboratory and professor at the Faculty of Civil Engineering of the National Polytechnic University Metsovio (NPUM) Konstantinos Spirakos in an interview with the Athens News Agency.

The new interdisciplinary research programme "Talis-NPUM SEISMO" is led by Professor Spirakos and involves civil engineers, architects, chemical engineers, surveyors, technicians - geologists and archaeologists, specifically aiming to develop a comprehensive methodology to assess the seismic behaviour of Greek monuments to be subsequently able to make the appropriate interventions, depending also on the seismicity of each region.

Similar studies are taking place at two emblematic monuments in Athens, namely the Temple of Hephaestus (5th century BC) and the temple of the monastery in Kessariani (11th-12th century), where the team will build a monitoring system with 6 measuring devices to record the seismic tremors (having selected one of the monuments initially).

The research project worth 600,000 euro is to report on the status of a monument and the varying degree of damage caused by earthquakes over time. Subsequently the laboratory of the Polytechnic University will perform experiments with models of monuments to check their reactions to a possible future earthquake in order to propose ways to improve their seismic behaviour.

According to Prof. Spirakos, such a complete study is being carried out for the first time, especially as regards the Temple of Hephaestus that is the best preserved monument, and its goal is to improve the behaviour of monuments over time.

Although nearly half of the buildings in Greece (48%) are made of stone, according to Prof. Spirakos there is no regulation yet for the inspection and repair of masonry structures, which can be applied by engineers after damage caused by earthquakes, regardless of whether the case is of a house or a stone monument. Therefore, the knowledge derived from the new research programme will help develop the conditions for, and creation of, such regulations.

"The intervention on a monument should be very careful but we need to be at least able to monitor the monuments by installing measuring devices", says Prof. Spirakos, adding that the three activities, namely the analysis of monuments, experiments with simulations in the laboratory and the installation of a measuring device, will allow the preservation of cultural heritage.

Before the launching of this new programme, the Polytechnic University Metsovio had installed similar devices on two other monuments, namely St. Louka Monastery and Daphne Monastery, to monitor the possible damage caused by earthquakes, the passage of heavy vehicles, cracks among others. "So far there has been nothing alarming," says Prof. Spirakos.

The aim is to use this seismic monitoring methodology for other monuments in the future. "In the case that the installation of measuring devices does not create a problem for the monument, archaeologists do not mind it. Unfortunately, such extensive studies are not frequently conducted. Few similar studies are carried out, not only in Greece but worldwide", states the specialist.

Seismic isolation of Greek monuments too

In addition, the seismic isolation technology will be experimentally tested for the first time on Greek monuments. It has already been implemented in the Acropolis Museum in order for the earthquake to be isolated underground, not spreading to the building. A model of a monument with seismic isolation will be built, which will be subjected to an earthquake in the laboratory of the Polytechnic University.

"We will explore the opportunity of isolating historical buildings from seismic activity in the future," states Prof. Spirakos. In practice, this means digging out a basement under the monument, where the special seismic isolators, on which the monument will "sit", will be placed.

"It would be better to install measuring devices on as many monuments in Greece as possible to monitor earthquakes. In Italy and other countries, this practice is already well advanced."

The cost per monument amounts to 50,000-150,000 euro, depending on the desired number of measuring devices to be installed and the amount of data to be collected. "The cost is not huge whereas the benefit is great", states the specialist.

Prof. Spirakos stresses that "many ancient monuments such as the Acropolis have a very good seismic behaviour and they have demonstrated it over time. When a monument has endured over time, it is either because it has not experienced a very strong earthquake or because it is very robust. In the future, however, there may be more powerful earthquakes. No one can totally exclude this possibility, depending on the faults in each region. If a new or historical building has stood up until the present day, it does not necessarily mean that it will stand up in the future too. We want to help historic buildings withstand a possible powerful earthquake in the future."

Tags: National Polytechnic University MetsovoSeismic protectionMonuments
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