Stress and buttress

I was trying to get a close look at the western turrets added to the Hagia Sophia in the 16th century CE by Mimar Sinan (featured photo) when I realized that I was looking at four buttresses to the church. I stepped back a little to photograph them in their entirety (below) and realized that they were actually flying buttresses. I’d thought that they were invented in the 12th century in France, so this surprised me.

Hagia Sophia is remarkably stable, given the frequency of earthquakes in Istanbul. Over 1500 years, the dome has had to be rebuilt only twice. A large part of this stability is due to the geometric design of the dome, with its supporting half domes built atop a central square section. However, recent studies found that the improperly cured bricks and mortar miraculously make the structure stronger than properly cured bricks of the 6th century would have. This is likely to be an accident of the hurried construction of the church, rather than deliberate materials science, especially since this technique was not used in any other Byzantine structure. Even with this fortunate accident, the pressure of the huge dome would have caused the structure to collapse if it were not for buttresses added over the years.

The four flying buttresses on the western facade, which you see in the photo above, are remarkable. They look like they are, at least in part, made of the same material as the rest of the western facade. This was rebuilt in 994 CE, within five years of its collapse during the earthquake of 989 CE. So I wondered whether the flying buttress was invented by the Byzantines before the French. The older view is stated clearly in this paper from 1935, “… we can at once discard any hypothesis which would date these buttresses to the ninth century, for the simple reason that flying buttresses were unknown before the twelfth century”. This paper buttresses this erroneous reasoning with an aesthetic judgement that these four are different from “ungainly masses” which were erected by Byzantine and Turkish architects, and so must have been made by French engineers who arrived here during the Venetian occupation.

The modern view is different. Flying buttresses have been discovered in buildings in Cyprus which were buried in the 8th century CE, well before its reinvention in France. So these buttresses which puzzled me could have been a Byzantine construction from the 10th century CE. In a structure as old as the Hagia Sophia, one seldom has a clear answer to questions of provenance unless there is contemporary documentation. For these four there is none, although the circumstantial evidence is that the buttresses are about a thousand years old. This raises the inverse question, could the egineering idea of flying buttresses, which began to be used from the 12th century in western Europe, have been carried there from Byzantium?

Earthquakes and travel

It turns out that we often travel in one of the most earthquake prone parts of the world: the plate boundary between India and Asia. This includes the Himalayas, much of Myanmar and Bangladesh, and large parts of western and southern China. Large earthquakes are infrequent enough that travelling is fairly safe. However, we have often been saddened by news of the destruction of places we loved. A year ago it was Kathmandu. This year, just as we begin preparations for a trip to Myanmar, there is news of a second serious earthquake in that country.

Learning about Myanmar is hard. It has cut itself off for so long that the world’s media pretty much ignores it. On the day of the quake there were reports across the world, but there has been no news later. When I set about investigating this, it took a while to get to Myanmar Times, which confirmed that the official count of deaths and injuries remains small: "Three people were killed and five injured, the Ministry of Social Welfare, Relief and Resettlement said." All is not well, however. Mizzima, another newspaper from Myanmar, reports: "The Director-General of UNESCO, Irina Bokova, has expressed her profound sympathy to the government and people of Myanmar after the devastating 6.8 magnitude earthquake that struck central Myanmar, including the ancient city of Bagan, causing loss of life and extensive damage to nearly 200 historic monuments and iconic pagodas." That means about 10% of the temples have been badly damaged.

I discovered that this is not the first time this has happened. The Myanmar times had an article which said "State Counsellor Daw Aung San Suu Kyi instructed the Culture and Religious Affairs Ministry yesterday to refrain from conducting urgent renovations on the 187 ancient Bagan pagodas and temples that were damaged by a 6.8-magnitude earthquake on August 24. She asked the ministry to discuss renovations with specialists from the United Nations Educational, Scientific and Cultural Organization (UNESCO), and to make their plans with technical support from the organisation". The article led on to another which reported on the fallout of an earthquake in 1975: "More than 600 ancient pagodas in Bagan have been ruined by botched renovation work, an architect has claimed. U Sun Oo, a member of the Bagan Management Plan Organising Committee, laid blame for the destruction on the practice of putting out complex and sensitive repair work to tender."

An older news report talked about some other problems in maintainance: "The long-running “limbo hotels” problem arose when the 42 hoteliers were cleared to build in Bagan by the Archaeology Department in 2013, but subsequently ordered to stop work and not to take in guests. The guesthouses, mostly modest establishments run by local residents, are deemed to be too close to Bagan’s famed temples, a factor that could put at risk the city’s bid to be included on the UNESCO World Heritage listing. As a result, the Ministry of Culture reinstated a zoning ban put in place in 1998 but rarely enforced since then. Earlier this year, 129 properties deemed to be operating too close to the ancient site, including the 42 guesthouses, were given a 10-year deadline to move to a special hotel zone."

The most disturbing report for would-be travellers comes from Bangkok Post, which reports "Another Myanmar earthquake of at least 7.0 magnitude is possible and it may affect Bangkok and northern Thailand in the absence of an aftershock in the neighbouring country after Wednesday’s 6.8-magnitude". I tried to confirm the basic facts, and found a site called Earthquake Track which indeed confirms that there are no aftershocks.

Bagan is one of the high point of a Myanmar itinerary, so this leaves us somewhat undecided.

Note added after the trip:

While all the snippets of news about damage to temples is true, Bagan is still stunning, and definitely worth traveling to. More than a year after the quake, there has not been another one. This could mean that the next one will release a lot of energy. Or it might not. Earthquakes are hard to predict.