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between 370 and 340 B.C., the Greek sculptor Praxiteles is believed to have
carved a statue of Hermes, the herald of the Olympian gods, holding the infant
Dionysos, the Greek god of wine. Although it has survived for more than 2,000
years in a seismically active land and currently is housed in its own room in
the Archaeological Museum of Olympia in Greece, the world-renowned statue has
recently received new protection.
Arguably one of the most important statues in Greece, Hermes holding the infant Dionysos (below right) has recently been seismically isolated to protect it in the event of an earthquake. Four blocks placed under a concrete base beneath the statue will allow the statue to swing like a pendulum in a quake, rather than crash to the floor. Courtesy of Michael Constantinou, University at Buffalo.
Seismic engineers at National Technical University in Athens and the University at Buffalo in New York recently completed retrofitting Hermes with a system designed to preserve the statue should a large earthquake strike near Olympia. In the event of a quake, the system allows the statue to gently sway side to side like a pendulum, rather than toppling over and crashing to the floor, says Michael Constantinou, an engineer at Buffalo who worked on the project.
The marble statue of Hermes is about 7 feet tall and stands atop a 3-foot-tall base. The entire structure weighs about 6,600 pounds. Beneath the marble base is a newly constructed concrete base built to support the seismic isolation system.
A carpet with some cushions underneath used to surround the statue to provide earthquake protection, Constantinou says. If an earthquake struck, the statue would have fallen on the cushions and broken into large pieces that could be easily put back together. Many statues around the world are protected this way, he says.
In the case of Hermes, however, the Greek Ministry of Culture wanted more safeguards, Constantinou says, so engineers began designing a system using friction pendulum bearings that seismically retrofit structures around the world, especially freestanding structures such as bridges and important buildings. The technology had not been applied to something as small as a statue before, he says, so it was challenging to figure out the geometry and exactly how much strength was needed to protect the statue. Additionally, Constantinou says, we were working against a clock this thing had to be sparkling by the time the Summer Olympics in Athens began last August.
Beginning in late 2003, the engineers ordered custom-built friction pendulum bearings 3-feet-by-3-feet square blocks that are about 8 inches high from a company in San Francisco. The bearings were shipped to Buffalo, where the engineers tested them in specially designed machines to determine that their properties met the specifications of the project, Constantinou says. Then they shipped the bearings to Greece, where engineers installed them beneath the concrete base.
The system has yet to be tested by an actual earthquake, but it is designed to withstand a temblor as big as magnitude 8 the maximum-sized quake that is thought to be possible in the region. The last large earthquake that struck Greece was magnitude 7, in 1983.
In addition to seismically protecting Hermes itself, the building in which the statue stands has been seismically strengthened, Constantinou says, so that in the event of an earthquake, the building may be damaged but should not collapse. After all, its not much good having the statue survive a quake if it then gets crushed by the building, says Andrew Stewart, an art historian at the University of California, Berkeley. As one of the most important statues in Greece, Hermes deserves special treatment, he says.
When combined with strengthening a building, such as by adding columns or putting up a new wall, seismically isolating single features is a good option to protect important artifacts when it is too difficult or costly to seismically isolate the entire building, Constantinou says. But it is no easy task, he says, to convince the administrators and archaeologists that the system will behave properly in the event of a quake.
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