Is Lisbon the birthplace of earthquake engineering?

Following the devastating earthquake of 1755, the Portuguese Prime Minster – Sebastião José de Carvalho e Melo (later known as Marquês de Pombal) took swift and decisive action to ‘bury the dead and heal the living‘. Remarkably no outbreaks of disease followed the earthquake, tsunami and fires and within a year parts of the city had been rebuilt according to a strict design and regulations set out by Melo and his team of engineers.

Eugénio dos Santos de Carvalho’s design for the new city, one of six put forward to Melo and the King, rebuilt the city on the original site but in a very different style and shape to what had been there before. The vision was for a sober and harmonious city whose main purpose would be trade and commercial growth. A reflection of Melo’s long term aim to rid Portugal of corruption, and a desire make it economically self-sufficient and commercially strong.

Manuel da Maia and Carlos Marde were the engineers who joined Eugénio dos Santos de Carvalho in implementing the building programme. Their approach of mass production methods and building standardisation was revolutionary at the time, and the harmony and elegance of their buildings in the Baixa remains striking. One of the building innovations they introduced, the Pombaline Cage, was in response to Melo’s desire for buildings that would be earthquake and fire resistant. The cage (gaiola) is wooden structure within the walls of the building, similar I guess to the metal frames you see these days in large scale buildings. Not only did the ‘gaiola’ enable them to create four floors rather than two, they made the buildings earthquake resistant. At the time of their original build, the engineers undertook large scale modelling tests using units of soldiers to create seismic vibrations by marching around the models. Perhaps the birth of earthquake engineering?

Whether these elegant buildings in Pombaline Baixa are still earthquake resistant is questionable however. Since the 18th century many have undergone significant modifications and others have fallen into a state of disrepair. There is consequently much uncertainty as to how many of these buildings would behave should another earthquake strike. If you want to know more about the construction of the buildings and Lisbon’s role in the history of earthquake engineering then do check out this excellent field guide from 2009.

When it came to the construction of Praça do Comércio, the square bordering the Tagus, the desire for sobriety and commercial activity seems to have been forgotten. Probably because the square was rebuilt on the remains of the square which once stood in front of the royal palace – Paços da Ribeira – there again it could have been because it was departments from Melo’s government that were housed in the new buildings which surround the new square! Whatever the reason for the breakaway from sober uniformity found on the streets leading to the square the result is stunning. The Praça do Comércio is full of glory, nobility and grandeur whether you view it from above or within.

Melo didn’t just initiate earthquake engineering and create a stunning new city for Lisbon, he also undertook an extensive study of the moments just before and after the earthquake. A survey was sent to all parishes asking whether animals behaved strangely prior to the earthquake, if there was a noticeable difference in well water levels, how many buildings had been destroyed and what other kind of destruction had occurred. It was one of the first studies of the impact of an earthquake across a region, and contributed hugely to the study of seismology within Portugal and internationally.