Lisbon Earthquake (1755): Quake, Tsunami and Fire on All Saints

The Lisbon earthquake struck the Portuguese capital on the morning of 1 November 1755, All Saints’ Day. A violent quake, a tsunami that surged up the river Tagus and fires that burned for days destroyed most of the city and killed tens of thousands of people. The disaster led to one of the first planned rebuildings of a European capital and shook the confidence of Enlightenment Europe.

Lisbon in 1755

Lisbon was one of Europe’s largest and richest cities, with around 200,000 inhabitants. Gold and diamonds from Brazil flowed through its port, funding grand churches, palaces and the new royal opera house, the Ópera do Tejo, opened only months earlier. Portugal was a devout Catholic kingdom, ruled by King Joseph I (José I), whose chief minister, Sebastião José de Carvalho e Melo, was rising in power.

The city had suffered earthquakes before, but nothing on this scale in living memory. Most people lived in tall stone buildings packed into narrow medieval streets, especially in the low-lying Baixa, the commercial district by the river.

The earthquake

At about 9:40 in the morning, while many residents were at Mass for the feast of All Saints, the ground began to shake. Witnesses described three distinct shocks over several minutes, with the strongest shaking lasting perhaps three to six minutes in total. Churches, palaces and houses collapsed, burying worshippers and people in the streets. Wide cracks were reported opening in the city centre.

The epicentre lay in the Atlantic Ocean, probably a few hundred kilometres south-west of Cape St Vincent, though its exact location is still debated. Without instruments, its size has been estimated from historical reports. Most modern studies place it at around magnitude 8.5–9.0. The shaking was felt across Portugal, Spain and Morocco and as far as France and northern Italy, and the water in lakes and canals oscillated in Britain and Scandinavia.

The tsunami

Survivors fled to open spaces, and many gathered on the new marble quay by the river, the Cais de Pedra, and the great riverside square, the Terreiro do Paço. Some noticed the water draw back, exposing the riverbed and lost cargo. About 30–40 minutes after the quake, the first of several large waves rushed up the Tagus estuary and into the lower city, sweeping people and boats away.

In Lisbon the waves are usually estimated at about 5–6 metres, with higher waves elsewhere. The tsunami devastated parts of the Algarve coast, struck Cádiz and the Huelva coast in Spain and killed many people in Moroccan ports. Hours later it reached Cornwall and Ireland, and it crossed the Atlantic to the Caribbean.

The fires

In the wrecked city, overturned candles from All Saints’ altars, kitchen fires and hearths started blazes that merged into a great fire. It burned for about five days, consuming much of what the quake had left. The Royal Ribeira Palace, which stood on the riverfront, was destroyed together with its royal library of some 70,000 volumes, archives of Portugal’s overseas voyages, and paintings by masters including Titian and Rubens. The Ópera do Tejo, the All Saints Royal Hospital and many churches and convents were lost.

The royal family survived because it had gone to the palace at Belém, outside the centre, after morning Mass. Joseph I was so shaken that he reportedly refused to live in a stone building again, and the court lived for years in a complex of tents and wooden structures on the hill of Ajuda.

Death toll and damage

Figures are uncertain because parish registers and other records were destroyed and the population was not precisely known. Many victims were never recovered from the rubble, the river or the fires, and refugees scattered across the countryside. Outside Lisbon, towns in the Algarve such as Lagos and Faro were badly damaged, and Spanish authorities reported more than a thousand deaths, many of them at Ayamonte near the Portuguese border. Contemporary claims of up to 100,000 dead are now regarded as too high by most historians.

Response and rebuilding

Carvalho e Melo took charge of the emergency. He had bodies collected and many buried at sea to prevent disease, organised food supplies, controlled prices and had looters hanged on gallows set up around the city. A famous phrase, “bury the dead and heal the living”, is often attributed to him, but its origin is uncertain and some accounts credit it to another nobleman.

The rebuilding was planned by a team of military engineers led by Manuel da Maia, with Eugénio dos Santos and Carlos Mardel. Rather than restore the medieval maze, they laid out the Baixa on a regular grid of wide streets, linking the Rossio square to the riverfront. The old royal square became the Praça do Comércio, the Square of Commerce, symbolising a modern trading state.

The new buildings followed standard designs and used the gaiola pombalina, or “Pombaline cage”, a flexible wooden lattice built into the walls to resist shaking. Tradition says models were tested by having troops march around them. This was among the earliest large-scale uses of earthquake-resistant construction in Europe.

Carvalho e Melo also sent a questionnaire to every parish asking how long the shaking lasted, how many aftershocks there were, whether wells changed and what damage occurred. The answers are an early systematic attempt to study an earthquake, and he is often regarded as a pioneer of seismology for it.

Key people

• Joseph I (1714–1777): king of Portugal, who gave his minister wide powers after the disaster.
• Sebastião José de Carvalho e Melo (1699–1782): chief minister, made Count of Oeiras in 1759 and Marquis of Pombal in 1769, who led the response and rebuilding.
• Manuel da Maia (1677–1768): chief engineer of the kingdom, who set out the options for rebuilding.
• Eugénio dos Santos (1711–1760) and Carlos Mardel (c. 1695–1763): architects and engineers of the new Baixa.
• Gabriel Malagrida (1689–1761): Jesuit preacher who called the earthquake divine punishment and was later executed by the Inquisition.

A shock to European thought

The destruction of a pious city on a holy day, while churches collapsed on worshippers and the red-light district reportedly survived, raised hard questions. Many clergy preached that the earthquake was God’s punishment for sin. Others saw it as a natural event that called for practical action.

Voltaire responded in 1756 with his Poem on the Lisbon Disaster, attacking the optimistic philosophy, associated with Leibniz and Alexander Pope, that “whatever is, is right”. He returned to Lisbon in his satire Candide in 1759, in which the hero survives the earthquake only to witness an auto-da-fé. Jean-Jacques Rousseau replied to Voltaire in a letter of 1756, arguing that people, not nature, bore much of the blame for crowding into tall buildings.

The young Immanuel Kant published three essays in 1756 seeking natural explanations for earthquakes. Though his theories were mistaken, they marked a shift towards scientific investigation. In Britain, John Michell’s study of 1760 proposed that earthquakes travel as waves through the Earth.

Political consequences

The disaster greatly strengthened Carvalho e Melo’s power. Over the next two decades he ruled Portugal almost as a dictator, reforming trade, education and administration in the spirit of the Enlightenment, while ruthlessly crushing opponents. He expelled the Jesuits from Portugal and its empire in 1759, and Malagrida, who had blamed the earthquake on sin, was burned in 1761.

The cost of rebuilding, along with Portugal’s existing problems, strained the economy. Yet the new Lisbon, with its arcaded squares and ordered streets, became a model of 18th-century urban planning.

Timeline

• 1755, 1 November, about 9:40 a.m.: The earthquake strikes Lisbon during All Saints’ Day services.
• 1755, 1 November, about 10:20 a.m.: The first tsunami waves sweep up the Tagus into the lower city.
• 1755, 1–6 November: Fires burn across Lisbon for about five days.
• 1756: Voltaire publishes his Poem on the Lisbon Disaster; Kant writes his essays on earthquakes.
• 1758: A royal decree approves the plan for rebuilding the Baixa.
• 1759: The Jesuits are expelled from Portugal; Voltaire publishes Candide.
• 1761, 21 September: Gabriel Malagrida is executed in Lisbon.
• 1775: The equestrian statue of Joseph I is unveiled in the Praça do Comércio.

Legacy

The Lisbon earthquake remains one of the deadliest earthquakes in European history, comparable to the Sicily earthquake of 1693 and the later Calabrian earthquakes of 1783. The Baixa Pombalina is now one of Lisbon’s most famous districts and has been proposed for UNESCO World Heritage status, and the ruins of the Carmo Convent stand as a memorial.

Why it matters

The 1755 earthquake destroyed one of Europe’s great capitals, but its response pointed to the modern world: state-led disaster relief, planned reconstruction, earthquake-resistant building and systematic scientific inquiry. It also forced Enlightenment thinkers to confront suffering and providence, leaving a mark on philosophy as lasting as the one on Lisbon’s streets.