One of the greatest natural disasters of modern times

On the 1st of November 1755, at around 9:40 AM, an intense earthquake hit the city, destroying most of its buildings, streets and squares. A tsunami followed the earthquake, between 60 and 90 minutes after the shakes, with waves of around 5m height coming from the Tagus river and flooding the city riverside, about to where is today Arco da Rua Augusta. Simultaneously, fires propagated, originated by the stoves in the houses and the candelabra in the churches, but also set by criminals that took the chance to plunder palaces and churches. D. José I and his family survived the Earthquake due to the princesses wishing to spend the public holiday at their countryside residence, the Royal Palace of Belém. The area of Belém, considered at the time one of the outskirts of the city, was populated by only palaces and farms, therefore, the effect of the earthquake was not as devastating as in the city.

Studied soon after its occurrence by countless figures linked to the social sciences, it was Kant who gave the discussion a more scientific approach, trying to explain the earthquake by implosions that occurred underground, that would happen especially in places near rivers or the sea, which were filled with water, as it was Lisbon. More than 265 years have passed since the fateful day and many were those who afterwards dedicated themselves to the study of the Great Lisbon Earthquake, researching to discover its most likely origin and the real impact it had in Lisbon and in the rest of world.


Earth, water and fire: a tragedy never comes alone

Triste tableau des effects causé par le tremblement de terre et incendies arrivés a Lisbonne le 1er novembre 1755, Séc. XVIII - 2a metade, Gravura © Museu de Lisboa / EGEAC, MC.GRA.1428

Tsunamis are rare occurrences in Europe, and this fact makes the 1755 tsunami an even more extraordinary event, since it crossed the entire Atlantic. As a transoceanic tsunami, it can be compared to the 2004 Sumatra tsunami and other tsunamis that cross the Pacific. Tsunamis with these characteristics are usually generated by large faults with very large movements. It is believed that a fault like that broke in 1755. According to the studies developed on this field, the fault that broke and deformed the ocean floor in 1755 was a fault 100km long and 50km wide. This same fault would have affected the ocean floor, it is estimated, in about 20m high, thus causing a transoceanic tsunami.

The records that we can access today corroborate this analysis, with reports on the impact of the tsunami in England, France, Brazil, Canada and the Caribbean where, for example, 3m waves were observed. The biggest impact was indeed in Portugal, but also in Morocco and southern Spain. Historical reports show that in Cadiz the waves would have reached more than 10m. As for Mainland Portugal, 10 to 15m waves would have reached Sagres area and in Lisbon it is estimated that they have reached 5m.


The birth of a new Lisbon

After the disaster, it was up to Marquês de Pombal, then Secretary of State, to reorganize the city and ensure that order in the kingdom was restored as soon as possible. Through plans developed by military engineers Manuel da Maia, Eugénio dos Santos and Carlos Mardel, the Secretary implemented a city plan in close relation with the Enlightenment ideals, with orthogonal wide streets and no longer a skyline dominated by church towers and palace domes.

Concerned that a similar tragedy would recur, Marquês de Pombal wanted to ensure that the buildings would have an anti-seismic system. A new construction technique - ‘gaiola pombalina’ -was developed, inspired by traditional methods and thereafter used systematically. Legend has it that the resistance of the structure was tested by the battalion led by Carlos Mardel. The soldiers marched vigorously to imitate seismic waves and the structure resisted. A global sewage system was also implemented and the water supply to the city was improved.


The Lisbon that was lost

Núncio Apostólico, O Cortejo de Entrada em Lisboa de Monsenhor Giorgio Cornaro, em 1693, Autor desconhecido, Séc. XVII, Pintura © Museu Nacional dos Coches / DGPC

On the days before the Earthquake, Lisbon impressed foreigners and travellers with its wealth, palaces and churches. The torrent of gold that came from Brazil allowed feasting parties and sumptuous fireworks, as well as the building of majestic monuments such as the brand new Opera House –inaugurated in March 1755, it was famous for its richness, sumptuousness and sheer size: 600 people in the audience, four stories of cabins (38 in total) and a stage so deep that it could accommodate 25 horses.

There were the golden ciboria of the Patriarchal Church, the coffers of the House of India, the jewels of the Church of S. Roque, the clocks and the silver plates of the aristocratic families. Inside the churches, diamonds glittered on linen, curtains and dressings, and the forged wrought ironwork of precious metals shined on the altars. Another way to show off your wealth was to exhibit your staff, the most extreme example being the famous Patriarchal Church, with its legion of musicians and singers. The Cardinal Patriarch circulated through the streets on his car with dozens of servants, dressed in wide breeches, with red hats and red robes, embroidered in gold, imitating the Pope’s entourage.