Not Demolished But Bent! Why Doesn’t the Leaning Tower of Pisa Collapse in Earthquakes?
We all know about Italy’s famous Leaning Tower of Pisa and the creative photos taken in front of it. But did you know that the situation that makes the Leaning Tower of Pisa lean also protects it from earthquakes?
The Leaning Tower of Pisa, or the Leaning Tower for short, is the bell tower of the cathedral in the Italian city of Pisa, known worldwide for its unintentional leaning.
There has been more than one severe earthquake that has struck this region since the Middle Ages in history, but the leaning tower has always remained standing. But why?
The Leaning Tower of Pisa has eight floors, including the bell room. Its height is 56 meters from the ground on the low side and 57 meters from the high side. The weight of the tower is estimated to be 14,500 tons.
The construction of the Leaning Tower of Pisa began in August 1173, but it took more than 100 years due to wars. Despite leaning dangerously at an angle of 5 degrees, the tower has survived four severe earthquakes since 1280 unscathed.
Considering the fragility of the structure, which barely managed to stand upright, it was subject to serious damage or even collapse in any seismic activity. Surprisingly, however, the tower did not collapse and the situation stunned the engineers.
A team of engineers and soil scientists led by Professor Camillo Nuti from the University of Rome Tre began work in 2018 to find the answer to this question.
After reviewing the available seismological, geotechnical and structural information, Professor Nuti and his team concluded that the Leaning Tower of Pisa’s standing was due to the “interaction of dynamic ground and structure”.
The height and hardness of the tower, combined with the softness of the soil, did not interact with the earthquake movements in any seismic activity. This also protected him from earthquakes.
Professor George Mylonakis from the University of Bristol, who is part of the research team, explained this situation as “the soft soil that causes the tilt of the tower protects it from collapse due to earthquakes and seismic events”.
The tower, barely standing upright, was expected to suffer severe damage from a moderate earthquake, but the tower’s “reaction” falsified expectations. The tower, which has been tilted 7 cm south in 100 years since it was completed, continues to survive the severe earthquakes in an oblique manner, even if it tilts.
