When the Waters Rise

One of the famous sites in Florence, Italy, is the Ponte Vecchio, the bridge over the River Arno. Ponte Vecchio means "old bridge," and it's true: it is old. It is believed that the bridge that first appears in records in 996 was built in Roman times. That wooden bridge collapsed in 1117; its stone replacement survived until 1333, when the Arno experienced one of the worst floods in its known history.

Giovanni Villani (c.1276-1348) was a Florentine banker who wrote the Nuova Cronica (New Chronicles), a year-by-year account of happenings in Florence in the 14th century. He wanted to make Florence as well-documented as Rome in terms of political events, historic buildings and monuments, and natural disasters. He reports on a flood that started on 3 November 1333.

By noon on the 4th, the waters overtook the banks and spread across the plain of the church of San Salvi, 1000 feet from the riverbanks. Florence, like many cities at the time, was walled, and Villani reports that by nightfall the city wall, which had been holding back the majority of the surge, crumbled from the force of the waters, allowing the rising tide to flood the city. Supposedly, there are scratches high up on columns in the Florence baptistry that survive to this day, showing the height reached by the water. According to Villani, the water flooded the courtyard of the commune (the seat of local government) to a height of 10 feet.

The Arno floods Florence again in 1966

Bridges on the Arno—the Carraia and the Trinità—both collapsed. The Ponte Vecchio stood a little longer, but logs and debris floating own the flood piled up against it, damming the river, which rose higher and flowed over the bridge, eventually bringing all but two central piers down.

All in all, 3000 people are reported to have died because of the flood. While it is often difficult to sympathize with casualties from so long ago and so far away, very recent events on the northeast coast of North America make for an apt comparison across the centuries of two tragedies. But there's even a third tragedy that needs mention here: 1333 was not the first, nor the last, time that the Arno flooded. A devastating flood in Florence in 1966 caused enormous damage; fortunately, modern methods of warning and rescue meant the casualties were kept to 1% of the 1333 totals. But the interesting footnote on the 1966 flood, when compared to 1333: it took place on 3-4 November!

Tornado Surprise

Tornadoes usually form when masses of warm, moist air and higher altitude cooler air meet. The cooler air descends, the warm air ascends, and the action creates a vertical funnel of swiftly rotating air. The majority of tornadoes in the world are created in the North American mid-west, when cool air coming over the Rocky Mountains meets the warm air rising from the Great Plains. With these geographical features, North America has what is called "Tornado Alley." Without these geographical features, tornadoes have a more difficult time forming; when they do, they are usually very weak. In fact, in the 1000 years prior to the 20th century, only about 2 dozen tornadoes were recorded in all of Europe.

Artist's impression of St. Mary le Bow being destroyed

Which makes it all the more interesting to learn that a tornado—the earliest known in England and perhaps the biggest ever experienced by that country—hit London in 1091. Once again, London Bridge fell down. The church of St. Mary le Bow was flattened, and four of its 26-foot-long rafters were driven into the ground with such force that only 4 feet remained showing. Several other churches were damaged or destroyed, as well as 600 houses. Estimates of the force of the tornado seem foolish, but people have tried, and they rate it an F4 on the Fujita Scale (F0-F5), with winds at 200 miles per hour or more. If that is true, then it is truly remarkable that there were only two deaths reported.

A tornado like that hitting London now would be striking a city of more than 8 million, but in 1091 estimates for London's population range from as few as 10,000 to as many as 20,000. In October of 1091, actually, there were even fewer people in London than usual. Thanks to the Anglo-Saxon Chronicle, we know that King William II was up north with his retinue and army fighting King Malcolm Canmore of Scotland (1038-1093). William prevailed, and was out of town when disaster struck. All things considered, it was probably the luckiest military campaign he ever undertook.

Trouble in Aleppo

Aleppo in Syria ranks with some of the oldest continuously inhabited cities in the world. There is evidence that people lived in that location at least 2000-3000 years before the Common Era. It became known outside of its immediate area when it became one of the western termini for the Silk Road, and goods passed through it on their way from the East to the Mediterranean and Europe.

Even before the establishing of the Silk Road, however, it saw prominence as a center of culture. In the 10th century, while it was the capital of and independent emirate, the scholar Al Farabi (briefly mentioned here) and the poet Al Mutanabbi (915-965) briefly created a golden age in Aleppo. It also managed to turn back attacks by European Crusading forces in 1098 and 1124.

Aleppo's trouble took place on 10-11 October 1138, when two earthquakes rocked the city, a small one followed by a larger that produced major destruction. Aleppo was home to tens of thousands at this time, but the initial shock on the 10th caused more fear than destruction, and drove many residents to the countryside. The quake of the 11th, however, justified their fears and destroyed much of the city. A contemporary historian, Ibn al-Qalanisi of Damascus, detailed the damage. The Aleppo Citadel that had been built by Crusaders (pictured above) partially collapsed, killing a reported 600 guards. A Muslim fort in the town of Atharib, 25 miles from Aleppo, was completely destroyed.

Aleppo was too prominent not to be rebuilt, and soon it was a thriving center for commerce and culture again, and being passed back and forth between the hands of different rulers: Saladin, Mamluks, Mongols, and finally Tamerlane in 1400, who killed many non-Mongol citizens and ordered a tower of their skulls to be built as a symbol of his rule.

...and the troubles continue to this day.

*An oft-quoted estimate of 230,000 deaths cannot be substantiated, and seems to have been created by a much later writer who was likely conflating the Aleppo quake with one a year earlier in Mesopotamia and/or one a year later in Azerbaijan.

The Pisan Mistakes

According to legend, a rich widow named Berta di Bernardo left 60 coins in her will for the construction of a campanile, a bell tower, for St. Mary's Cathedral in Pisa. A 55-meter tower was planned, belvedere style so that people could walk up the outside and enjoy the view. Ground was broken August 9, 1173.

The architect/builder is unknown. Either he was simply undistinguished, or he was careful to keep his name out of the public eye once the project was begun in order to avoid the inevitable ridicule. Pisa was built at the junction of two rivers, the Arno and the (now dried and gone) Auser; when the builder dug a 3-meter deep hole for the foundation, he found only river clay and sand. This lack of bedrock did not deter him. He proceeded to build what was designed to be a 14,000-ton structure on top of this soft foundation; by the time he got to the third level in 1178, it had already started to list to one side.

They had no way to change the ground on which it stood, and they didn't want to give up the project, so they built the next floors with one wall higher than the other, so that the upper floors wouldn't slant.

A series of financial problems and wars with neighboring city-states (mostly Florence, but Pisa also lost a major conflict with Genoa) meant the campanile wasn't finished until 1319. Nothing they did could fix the increasing list. But then, nothing they did would have. Adding the bells? More leaning. Deciding to add an impressive 3.5 ton additional bell? More leaning. Even so, the tower was only leaning by five degrees in 1837, when Alessandro della Gherardesca decided to turn an embarrassment into a tourist attraction by exposing the famous flawed foundation. He dug around the base...below the water table. The space flooded, the clay and sand softened more, and over the course of a few days, the tower leaned another meter!

In 1934, the idea arose to drill holes in the foundation and force grout into them. It looked good on paper; in reality, it increased the tilt. Tinkering in 1966 and 1985 just made it worse, and the tower was closed to the public in 1990.

Years later, the combination of a steel corset around the base, concrete, and counterweights were supposed to be the ultimate fix. They weren't, although they did almost cause the whole tower to break apart from stress. Finally, someone decided to go to the root of the problem. They dug away at the foundation on the other side of the tower, hoping it would lean back the way it had come. A little over 800 years of tinkering since the problem first appeared, and not only was the tilt reduced, but the tower was stabilized and re-opened to the public. Once again, tourists can climb the tower and take photographs looking out over Pisa, rather than just ground-based pictures of them appearing to hold up the tower with their hands.