Preventing earthquake damage to Italy’s historic structures.
In the days following the Emilia-Romagna earthquakes in May 2012, Agata Maini watched as fear spread through her community of San Felice sul Panaro like the aftershock that woke her early one morning.
Gutted by a 5.9 magnitude earthquake on May 29, the town’s historic center lay in ruins, 1,000 years of its past wiped out. Churches had collapsed, homes were destroyed, and the famous Rocca Estense castle bore deep scars along what few walls remained standing after the clouds of dust subsided.
“The worst part about this is that nothing will be back like it used to be,” said Maini, a 25-year-old copy writer. For someone who used to hate the sound of church bells, the silence that echoed across the city was a “terrifying” alternative.
The devastation in the Emilia-Romagna province is all too familiar to Italians. While Italy is counted among the world’s leaders in seismology and earthquake engineering, the question remains: How can the country’s rich heritage be protected from such an unpredictable natural event?
For places like Urbino, where Renaissance treasures such as the Palazzo Ducale and the Duomo stand vulnerable, the risks are ever-present.
That’s why Roberto Romeo, a professor of earthquake engineering at the University of Urbino, has spent his career searching for answers. “We should never underestimate risk, especially in areas like Urbino, but also in many other areas where we have very old buildings,” he says.
To prevent natural events from becoming natural disasters, communities need reliable information about their seismic risk, he says. Such information comes from “microzonation” studies, an area in which Romeo has worked.
As their name implies, microzonation studies can pinpoint for a small area such as a municipality the frequency and maximum possible strength of seismic activity as well as the potential level of damage. In 2011, the Italian government pledged 1 billion euros for a microzonation study of 3,900 of the most seismically hazardous municipalities across the country. The project, which also covers some of the cost of retrofitting public and private buildings, will be completed in 2018. With this data, local and federal governments can determine appropriate building codes and safety measures, and set priorities for retrofitting projects, Romeo says.
At the top of Italy’s priority list are several UNESCO world heritage sites, says Ross Stein, geophysicist at the U.S. Geological Survey in Menlo Park, California. The Basilica of San Francesco d’Assisi, for example, underwent seismic retrofitting in 1999 after suffering severe damage to its ceiling and frescoes during the 1997 Umbria and Marche earthquake.
By law, buildings in seismically active regions of Italy are required to be earthquake-proof. But no single formula exists for protecting historical structures. Each building is unique and must be retrofitted with the architect’s original design in mind.
Earthquake engineer Michele Palmieri, for example, has dedicated himself to finding a reliable and cost-effective way to preserve the stone temple of Marte Ultor, a trademark of Rome’s heritage located in the Forum of Augustus ruins. Palmieri is part of a team of researchers at the European Centre for Training and Research in Earthquake Engineering (EUCentre) in Pavia, Italy, who study the effects of earthquakes on historic structures and stone masonry buildings—the most common type of structure in Italy, and the most vulnerable to quakes.
Using an earthquake simulator, Palmieri analyzed the effects of ground shaking on the Roman columns. Then he devised a method of reinforcing a column by drilling a hole down its center and inserting a steel bar. In the event of an earthquake, the bar would take the brunt of the damage but could later be removed, reducing aesthetic damage to the original structure.
Retrofitting is a delicate and expensive procedure: Last year’s restoration of the Duomo of Milan cost 25 million euros, according to BBC News. But the cost of losing historical structures, Stein says, far outweighs the cost of preventative measures.
Urbino is no stranger to that cost analysis. While not on a major fault, Urbino is surrounded by two of Italy’s most seismically active areas, the Apennine mountain chain and the Adriatic coast. The Marche region, in which Urbino sits, frequently experiences earthquakes, although generally of a magnitude lower than those in southern Italy.
In 1741 and 1781, Urbino endured two quakes over magnitude 6, an intensity at which buildings can suffer severe damage. While the initial impact of the quakes was minor, years without restoration caused the Duomo to collapse in 1789.
In 1997, high-intensity quakes rocked the Umbria and Marche regions over a period of months. The walls and floors of the Palazzo Ducale became detached, the Duomo suffered damage to its bell tower and walls, and churches across the city experienced cracked walls and roofs. The city of Fabriano suffered greater damage, requiring several paintings to be rescued from churches.
Urbino remains vulnerable, says Maria Rosaria Valazzi, superintendent for the historical, artistic and ethno-anthropological heritage of the Marche. She notes that the twin towers of the Palazzo Ducale are currently undergoing a two-year seismic retrofitting to prevent future damage.
But finding the resources for retrofitting is “not so simple,” says Valazzi. The Palazzo Ducale project would not have been possible without economic support from Italy’s Ministry of Cultural Heritage.
And then there’s the human calculus: Is money better spent earthquake-proofing historical buildings or structures such as schools and hospitals that may save more lives? It’s a difficult choice, says Stein, where “civic values come into play.”