Why does the leaning Tower of Pisa not fall?
The Leaning Tower of Pisa is one of Italy's most famous landmarks is. This tower, with a 3.97-degree incline, has stood erect for over 800 years, despite earthquakes, hurricanes, and wars.
About the tower
The Leaning Tower of Pisa is one of the most recognised monuments in the world. It is a freestanding bell tower for a nearby cathedral in Tuscany, Italy. The tower took almost 200 years to complete, situated behind the Pisa Cathedral. It is the third-oldest structure in the city's Cathedral Square, after the cathedral and the Pisa Baptistry. It was designed to stand 56 metres high and was constructed of white marble. Currently, it stands 55.86 metres from the ground on the low side and 56.67 metres on the high side.
What caused the inclination?
The tower began to sink after construction had progressed to the second floor in 1178. This was due to a mere three-metre foundation, set in weak, unstable subsoil, a design that was flawed from the beginning. Construction was subsequently halted for almost a century, allowed time for the underlying soil to settle. Numerous efforts have been made to restore the tower to a vertical orientation or at least keep it from falling over. Most of these efforts failed; some worsened the tilt. By 1990, the tilt had reached 5.5 degrees. The structure was stabilized by remedial work between 1993 and 2001, which reduced the tilt to 3.97 degrees.
How does the leaning tower remain standing?
In an effort to compensate for the tilt, the engineers built upper floors with one side taller than the other. Because of this, the tower is curved, giving it a banana shape. Starting in 1993, 870 tonnes of lead counterweights were added, which straightened the tower slightly. The tower’s centre of gravity has since been meticulously controlled within its base. The bells were silenced to relieve some weight, and cables were cinched around the third level and anchored several hundred meters away. Earth was siphoned from underneath the foundations, decreasing the lean by 44 cm to 4.1 metres; the work was completed in May 2001, and the structure was reopened to visitors. The tower continued to straighten without further excavation, until in May 2008 sensors showed that the motion had finally stopped, at a total improvement of 48 cm. Engineers expected the tower to remain stable for at least 200 years. In the end, the Leaning Tower of Pisa does not fall because its centre of gravity has been carefully kept within its base.
Will it ever fall?
It's reasonable to think that because the tower of Pisa has been leaning for nearly 840 years, it will continue to defy gravity. Unfortunately, since the first brick was set, the famed structure has been in risk of falling. Regular monitoring is performed on the site and a large number of sensors were put on the tower which ensure that any anomaly in the Tower's stability is quickly discovered and action is taken. Given all of this, the Tower will never be in serious danger of collapsing unless Tuscany and Pisa are struck by a massive earthquake. Natural disasters are unpredictable, but big earthquakes have not occurred in Tuscany in the last 800 years. So, we are unlikely to see the Leaning Tower of Pisa's wreckage anytime soon.