- Title: Mystery of earthquake-proof Leaning Tower of Pisa solved
- Date: 7th June 2018
- Summary: BRISTOL, ENGLAND, UK (MAY 17, 2018) (REUTERS) (SOUNDBITE) (English) PROFESSOR GEORGE MYLONAKIS, UNIVERSITY OF BRISTOL, SAYING: "We are much more optimistic about the Tower of Pisa. The earthquakes there are more modest in magnitude and intensity, and the effect of the ground - the help that the tower receives from the ground - is so important and so strong that we are opti
- Embargoed: 21st June 2018 10:32
- Keywords: Leaning Tower of Pisa Roma Tre University Opera della Primaziale Pisana University of Bristol earthquakes seismology
- Location: PISA, ITALY / BRISTOL, ENGLAND, UK
- City: PISA, ITALY / BRISTOL, ENGLAND, UK
- Country: Italy
- Topics: Science
- Reuters ID: LVA0098JB86ZF
- Aspect Ratio: 16:9
- Story Text: It's a mystery that has puzzled engineers for decades: how has the Leaning Tower of Pisa remained upright despite being subjected to numerous earthquakes over the years?
New research has concluded that a unique combination of location and construction - known as dynamic soil-structure interaction (DSSI) - helped the tower withstand at least four strong earthquakes, and many more minor ones, that have hit the region since 1280.
Professor George Mylonakis, from Bristol's Department of Civil Engineering, told Reuters the softness of the foundation soil beneth the tower helped it absorb any tremors.
"As the earthquake waves reach the tower it somehow rides the waves and doesn't move. So the soil moves but the tower doesn't move; like riding the waves. So had the soil been stiff, the waves would have hit the tower and the tower would have possibly if not probably collapsed," said Mylonakis.
The ground beneath the tower was a pre-historic riverbed, making the soil there softer and less rigid. Ironically, Mylonakis said, it's the same soil that caused the tower to lean precariously at a five-degree angle which can be credited for helping it survive various seismic events.
He added that the soil below, combined with the tower's height and thick marble walls, provided the perfect dynamic soil-structure interaction to mitigate the type of seismic events that the region is prone to.
"These earthquakes produce waves that do not resonate with the tower, and this is a very significant factor that has contributed to the survival of the structure."
The 14,000-tonne free-standing bell tower, an internationally recognised architectural symbol of Italy along with Rome's Colosseum, was built in several stages between 1174 and 1370.
Mylonakis said the new findings give hope that the Leaning Tower will continue to stand tall for generations to come.
"We are much more optimistic about the Tower of Pisa. The earthquakes there are more modest in magnitude and intensity, and the effect of the ground - the help that the tower receives from the ground - is so important and so strong that we are optimistic it will survive for hundreds if not thousands of years," he said.
The study was conducted by a 16-member research team, led by Professor Camillo Nuti at Roma Tre University, and funded by Opera della Primaziale Pisana. The results of the research will be formally announced at the 16th European Conference in Earthquake Engineering in Thessaloniki, Greece which runs 18 to 21 June 2018. - Copyright Holder: REUTERS
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