The Leaning Tower of Pisa is gradually straightening thanks to the stabilization works on it, a study by Italian scientists has found, cited by the Daily Mail and the BTA.
The lean of the tower has been a cause of concern for engineers, historians and thousands of tourists for decades.
An 11-year stabilization project reduced its lean by 38 cm by 2001, and in the 21 years since then the tower has straightened another 4 cm. Although the lean has been reduced, the tower body continues to “swing” with an average of about 0.5 mm per year according to Nunciante Scuglia, professor of geotechnics at the University of Pisa. “Today, however, the stability of the bell tower is better than expected,” he told Italian news agency ANSA.
The bell tower, a symbol of the power of the maritime republic of Pisa in the Middle Ages, has managed to survive unscathed at least four major earthquakes that have hit the region since 1280. A 2018 study found that it was the softness of the soil beneath the foundations that was initially responsible of its sway, to protect it from strong shocks. According to theories, the 57-metre tower leaned during construction, which began in 1173. The reason lies in a faulty design, the foundations of which are only three meters deep and are built on weak and unstable soil.
The soil under the foundations is softer on the southern slope, which gave rise to the infamous slope.
The builders tried to make up for it by building the top eight floors. They made their tops shorter on one side, making the structure curved as well as leaning.
Construction was not completed until 1319 due to various battles between Pisa and Genoa, Lucca and Florence, but these pauses gave time for the foundation soil to settle.
In 1990 the tower still leaned 5.5 degrees to the south and was closed to the public lest it collapse.
After implementing several unsuccessful strategies to straighten the structure, the engineers decided to try the so-called “soil mining”. This involved excavating two truckloads of earth under the north side of the tower, then using steel cables to pull it upright. The procedure worked, but the team found that the building kept leaning during the winter rains, as a large body of water collected under its north side, so drains had to be dug so that the water flowed in special wells and thus kept the foundations stable. .
The project was completed in 2001 and involved rectifying the tower by 38 cm or 0.5 degrees. Adjustments have since been made, with the slope continuing to gradually decrease.
Experts declared the Leaning Tower of Pisa safe for the next 300 years during an inspection in 2005, ANSA said. They also said advances in technology mean the tower will one day be fully erected. In 2013 another check revealed that the Italian landmark had risen another 2.5 cm from 2001 onwards. The latest study suggests that the tower has risen another 4cm since 2001.
Today the lean of the Leaning Tower of Pisa is double what it was when it began its existence in 1350.
