Earthquake, wave and fire: the destruction of Lisbon, 1 November 1755

The weather was calm and clear. Miguel Tibério Pedegache, a Lisbon army officer of Swiss descent and a man of the Enlightenment, noted the barometer at 27 inches 7 lines and Réaumur's thermometer at 14 degrees. Then, at nine o'clock and forty minutes in the morning, “shook the earth with three impulses”.1 source1 source

It was Saturday 1 November 1755, All Saints' Day, and many churches were full of people at Mass. The first shock lasted, by one witness's count, six or seven minutes. Joaquim José Moreira de Mendonça, who published a history of earthquakes in 1758, felt two distinct tremors inside it. Two more strong, shorter shocks followed and brought down much of what was still standing.1 source1 source

Along the river the next danger came from the water. The Tagus drew back, uncovering a riverbed nobody had seen before, and then the sea came in.2 sources2 sources

By nightfall a column of smoke stood over the centre of the city. Fires had broken out in the palace of the Marquis of Louriçal, in the church of São Domingos and near the Royal Palace and the Customs House, and for four more days they burned through rubble and bodies alike.1 source1 source

Lisbon in 1755 was the capital of a seaborne empire and one of the richest cities in Europe, with about 250,000 inhabitants. It had forty parishes and sixty-five convents.1 source1 source

The king, José I, had been acclaimed on 7 September 1750. On the riverfront stood his Ribeira Palace, with a royal library of about 70,000 volumes, beside the warehouses of the Casa da Índia, which handled the trade with Asia. A new opera house had just opened, and a new Patriarchal church, the seat of Lisbon's patriarch, had just been built.2 sources2 sources

Earthquakes were not new. Pedegache pointed to earlier great shocks in Portugal in 1309 and 1531, and wondered whether they came back at regular intervals. What nobody in 1755 knew was where they came from: the 1755 shock started offshore, south-west of Portugal, and geologists still argue over which fault broke.2 sources2 sources

In the Tagus the water rose and fell three times in a few minutes, climbing by one account some fifteen English feet above the highest spring tides. Witnesses saw it flood the Customs House, the Terreiro, the great square by the palace, and the São Paulo quarter. Studies of these descriptions conclude that the sea ran about 250 metres into the lower town, held back in part by the old city wall built by King Fernando.1 source1 source

The wave reached far beyond Lisbon. Reports describe waves of 10 to 15 metres at Cape St Vincent and along the Gulf of Cádiz. At Albufeira, in the Algarve, the parish priest wrote that the sea took the whole quarter of Santa Ana, seven streets, leaving no sign of the houses. In Funchal, on Madeira, the water rose fifteen feet above the high-water mark about an hour and a half after the shock. The tsunami was seen along North Atlantic coasts and in Central and South America.1 source1 source

The shaking was felt in North Africa and as far as the Canary Islands, Madeira and the Azores. Kant, working from newspaper reports, found that the waters had been disturbed almost at once from Åbo in Finland to the West Indies, with few coasts spared.2 sources2 sources

Moreira de Mendonça judged that more than two-thirds of the city was left uninhabitable. The Ribeira Palace, the new opera house and the new Patriarchal church collapsed completely. The royal library vanished, and so did the goods stored in the Casa da Índia. At least twenty palaces of the high nobility were destroyed, with their paintings, libraries, furniture, silver and jewels.1 source1 source

The churches suffered worst, because so many people were inside them. Of the sixty-five convents in the city only eleven stayed standing, and Lisbon's six main hospitals, partly destroyed, had to be emptied. So did the court gaols.1 source1 source

Some things survived by luck. The royal archive, the Torre do Tombo, was kept in a tower of São Jorge Castle. The tower fell, but the fire never reached it. Its keeper, the military engineer Manuel da Maia, had a wooden hut built on the castle's parade ground for the papers saved from the rubble and set about listing what was left. The royal family was unhurt: on the morning of the earthquake they were at their country houses at Belém. The court moved to a wooden palace at Ajuda, the Real Barraca, and stayed there until 1794.2 sources2 sources

Nobody counted the dead, and the numbers have been argued over ever since. Bodies were buried under rubble, burned in the fires or carried off by the river. Thousands were taken out by barge, weighted and dropped into the sea beyond the bar of the Tagus, with no funeral rites.1 source1 source

Contemporary figures varied widely. Pombal, keen to stop alarm, told the colonial governors that 6,000 to 8,000 people had died. The papal nuncio, the pope's ambassador, told Rome about 40,000. Voltaire's poem spoke of a hundred thousand.2 sources2 sources

The gap between 10,000 and 40,000 has not closed. Even the tsunami's share is disputed: Zebrowski's 10,000 is more than ten times the estimate of the Portuguese tsunami specialists. What is not in doubt is the scale of the loss. Álvaro Pereira, an economic historian, puts the direct cost of the disaster at 32 to 48 per cent of Portugal's GDP.3 sources3 sources

The king at once set up a crisis command under Carvalho e Melo, and within 24 hours it was at work. The Duke of Lafões took charge of justice, the Marquis of Marialva of military matters and the Marquis of Alegrete, president of the city's Senate, of food supplies and clearing the streets. The city council and the army were told to put all their men and materials at its disposal.1 source1 source

Prices, wages and rents were frozen at their pre-earthquake levels, and fish and grain were sold under the eye of city officials to stop hoarding. Ships in the harbour were searched for loot and made to unload timber and food. Soldiers guarded the roads into Lisbon, and looters caught in the ruins were tried summarily and hanged on gallows set up around the city.1 source1 source

Survivors camped outside the city, then were made to come back. About 9,000 wooden shacks went up in six months, many in Belém, Alcântara and the new parish of Santa Isabel, where some 25,000 people were living by 1756, many of them in shacks. To pay for rebuilding, a 4 per cent duty was added to imports from 1756, Brazil was told to contribute 1,200 contos (1.2 billion réis) over thirty years, and a papal brief of 25 August 1756 diverted a third of parish church revenues to rebuilding churches.1 source1 source

The emergency made Carvalho e Melo's career. In the next few years he had members of the high nobility, accused of an attempt on the king's life in 1758, sentenced to death, and expelled the Jesuits in 1759, and his propagandists presented the earthquake as the start of a new era of progress.2 sources2 sources

A month after the disaster, on 4 December 1755, Manuel da Maia, an elderly and experienced military engineer, sent the Duke of Lafões the first part of a dissertation on rebuilding Lisbon. He set out five options: rebuild the city as it was; rebuild it with straighter, wider streets; do that but allow only two-storey houses; level the ruins and draw a completely new plan; or abandon the old city and build a new Lisbon at Belém, which he preferred.1 source1 source

The government chose to rebuild the Baixa, the flat lower town between the hills, from scratch. In the second part of his dissertation Maia laid down the rules: the new streets should be wide, and no building should be taller than its street. The third part is dated 31 March 1756.2 sources2 sources

Three teams of engineers drew plans. The one adopted was by Eugénio dos Santos, architect of the works of the Ribeira Palace and the city Senate, approved and refined by the engineer Carlos Mardel. Dated 1758, it levelled the ground over the rubble and laid out a grid of straight streets between two great squares: the Rossio inland and the new Praça do Comércio on the river. The Senate, the Stock Exchange, the Arsenal and the royal courts were planned inside the grid.1 source1 source

The buildings were standardised: the same heights, the same windows and doors, with parts made in advance and assembled on site. Inside the walls went a timber framework, the gaiola or “cage”, meant to give the buildings elasticity and strength when the ground shook. Pombal signed many of the façade drawings himself, and the district is still called the Baixa Pombalina.1 source1 source

Work formally began after a law of 12 May 1758 set out owners' rights and gave each plot five years to be rebuilt, a deadline that was not kept. In the middle of the Praça do Comércio the government set up an equestrian statue of José I, with Pombal's portrait on the pedestal.1 source1 source

News travelled slowly. Voltaire, in Geneva, may only have heard of the disaster by letter on 23 November. The Gazeta de Lisboa gave it a few lines. Abroad, newspapers filled the gap with survivors' letters, some real and some invented, and with prints by artists who had never seen Lisbon and drew houses like their own.2 sources2 sources

Many preachers, Protestant and Catholic, said the earthquake was God's punishment. In London the Methodist John Wesley published Serious Thoughts Occasioned by the Late Earthquake at Lisbon in 1755, and it went through several editions before the end of the century.1 source1 source

Voltaire disagreed in verse. His Poem on the Lisbon Disaster of 1756 attacked the optimism of Leibniz and Alexander Pope, summed up in the phrase “all is well”. As Rousseau later put their case, God had chosen, of all possible arrangements of the world, the one with the least evil and the most good.3 sources3 sources

Jean-Jacques Rousseau answered the poem in a letter of 18 August 1756. Most of our physical ills, he argued, are our own work, and Lisbon was no exception. In 1759 Voltaire published Candide, a satire that recalls the Lisbon earthquake and mocks the idea that a battle, an auto-da-fé (the Inquisition's public sentencing of heretics) or an earthquake could be part of God's plan.2 sources2 sources

The German philosopher Immanuel Kant published three short works on the earthquake in 1756. He explained it as a natural event: heated matter spreading through passages under the earth until it met sulphur, oil or pitch and caught fire. The theory was wrong, but he looked for causes in nature and refused to search the movements of the earth for God's purposes.4 sources4 sources

In 1756 Pombal's government sent a printed questionnaire of thirteen questions to the parish priests of every diocese in Portugal. Advised by Pedegache, the physician António Ribeiro Sanches and the astronomer Joaquim Soares de Barros, it asked about what could be observed, not about omens. Spain ran a damage survey too, but a simpler one.1 source1 source

The replies are kept in the Torre do Tombo, and Francisco Luís Pereira de Sousa compiled and studied them between 1919 and 1932. Elsewhere scientists went to work on the same event. Kant checked the times reported from Lisbon against Madrid, allowing for the difference in longitude. The Cambridge fellow John Michell built a long paper for the Royal Society around the Lisbon shock.4 sources4 sources

Reports of what people felt and saw, known as macroseismic data, are still the main evidence for the earthquake's size. In 2020 the seismologist João Fonseca, of the University of Lisbon's Instituto Superior Técnico, used 1,206 such data points from Portugal, Spain and Morocco to estimate the earthquake's size, and arrived at a much lower figure than his predecessors.1 source1 source

Where the earthquake started is still debated. The geologist António Ribeiro ruled out the much-cited Gorringe Bank, because its fault has been inactive for about five million years. He argued that the Marquês de Pombal thrust, about 100 kilometres south-west of Cape St Vincent, was at 55 kilometres too short to produce the shock alone, and that the Horseshoe fault beside it was the most plausible partner.1 source1 source

The Carmo church, on the hill facing São Jorge Castle, was founded in 1389 by Nuno Álvares Pereira, constable of the kingdom and one of Portugal's medieval heroes, who chose it for his grave. The earthquake badly damaged it and the fire that followed destroyed almost everything inside. Rebuilding in neo-Gothic style began in 1756 and stopped for good in 1834, when the religious orders were abolished. In the mid-nineteenth century the roofless nave was left open to the sky as a memorial to 1755.1 source1 source

Below it lies Pombal's city. The grid of the Baixa still runs from the Rossio to the river, and José I still rides in the middle of the Praça do Comércio. The triumphal arch at the end of Rua Augusta is crowned by statues of Glory, Genius and Valour, with figures from Portuguese history, Pombal among them, below; since 2013 visitors can climb to the top.2 sources2 sources