Stuff You Missed in History Class

Episode: Great Lisbon Earthquake of 1755
Hosts: Tracy V. Wilson & Holly Frey
Date: February 18, 2026

Episode Overview

In this episode, Tracy and Holly examine the monumental Lisbon Earthquake of 1755, exploring its causes, destructive impact across Europe and North Africa, and the profound influence it had on society, Enlightenment thinking, and disaster response. The hosts trace the seismic event’s ripple effects far beyond Portugal, including Morocco and across the Atlantic, discuss the devastation in Lisbon, and reflect on how the disaster reshaped both the city and philosophical debates in Europe.

Main Discussion & Key Insights

1. Personal Connection and Introduction

• Tracy’s Experience in Morocco:
  • Tracy shares how references to the earthquake kept coming up during a recent trip to Morocco, as many historical sites were affected.
  • She recalls, “Our guides would say that a site had been uncovered in the earthquake or damaged in the earthquake. And it made me really curious... this earthquake was obviously also a big enough deal in Morocco that people are still talking about it at historic sites 200 years later.” (03:28)
• Literary Context:
  • Tracy notes she’d encountered the earthquake in Voltaire’s Candide but had not fully understood the true historical scale.

2. The Earthquake: Facts and Timeline

• When & Where:
  • Occurred November 1, 1755 (All Saints’ Day) at around 9:40 a.m.
  • Epicenter estimated on the boundary between African and Eurasian tectonic plates, in the Atlantic Ocean southwest of Lisbon.
  • Holly: “There were three distinct periods of shaking over the course of about 15 to 20 minutes.” (04:34)
• Magnitude & Reach:
  • Estimated at 8.5–9 on the moment magnitude scale.
  • Felt as far as Britain, Ireland, Germany, the Azores, and Cape Verde; aftershocks lasted months.
  • Major impact on Portugal, Spain, Morocco—earthquakes in the region were rare but known.

3. Destruction & Tsunami

• Tsunami Devastation:
  • Waves up to 20 meters (66 ft) overtopped city walls in Morocco, flooding interiors.
  • Tsunami reached Cornwall, Newfoundland, the Caribbean, Brazil, and even left sediment in Scotland.
  • Tracy: “Having been in some of those cities, that prospect is terrifying to me.” (08:04)
• Death Toll:
  • Estimates range wildly: 10,000 to 100,000 dead across affected regions.
  • Hard to pinpoint due to lack of census, quick burials, and multiple events around the same time.

4. Lisbon Before & After the Earthquake

• Lisbon Context:
  • Fourth-largest European city; major wealth from colonial empire, especially gold from Brazil and trade—often benefiting Britain.
  • Large, influential clergy and strong ties to Catholicism and the Inquisition.
  • Holly: “Portugal had also been on the periphery of the scientific revolution... In the 16th and 17th centuries, the Inquisition censored published material in Portugal.” (21:32)
• Religious and Social Impact:
  • Earthquake struck during All Saints’ Day mass; churches and monasteries were heavily frequented and highly vulnerable.
  • Tracy: “Churches and monasteries were typically very, very tall and architecturally complex, and a lot of them just collapsed during the earthquake with people inside.” (22:53)
• Destruction in Lisbon:
  • 4/5 of central Lisbon destroyed.
  • Fires, started by falling candles and possibly looters, raged for five days.
  • Royal palace, library, and opera house (just one month old) destroyed.
  • 35 out of 40 city churches gone, approx. 30,000 dead in the city (10% of population).

5. The Government & Rebuilding Response

• Rise of Pombal:
  • Sebastiao José de Carvalho e Melo (later Marquis of Pombal) led the recovery, empowered by King José I.
  • His coordinated response is seen as a model for modern disaster relief.
  • Apocryphal quote from Pombal to the King:
    • “Bury the dead and feed the living.” (29:32)
• Relief Measures:
  • 241 recovery provisions established: disease prevention, relief, food distribution, rebuilding.
  • Taxes suspended; sardine industry nationalized to support food supply.
  • Foreign aid: Britain sent funds and materials—one of the earliest cases of formal international disaster aid.
• Martial Law and Social Measures:
  • Price controls, prosecution of looters, mass burials (including at sea), discouragement of mass flight from the city.
  • Tracy: “These mass burials included people across the spectrum of race, ethnicity, age, and social status.” (32:38)

6. Urban & Architectural Transformation

• Urban Planning:
  • Replacement of the old medieval street grid with wide streets and squares to act as firebreaks.
• Earthquake-Resistant Design:
  • Gaiola Pombalina: Wooden cage-like structural system within masonry buildings to absorb shocks.
  • Buildings limited to 3–5 stories, designed to minimize debris falling into streets in future quakes.
  • Majority of new houses with shops on the ground floor, residences above.
• Long-Term Economic Impact:
  • Portugal lost between a third and half of its GDP; economic and colonial slowdowns ensued.

7. Seismology & Enlightenment Thought

• Documenting the Earthquake:
  • Pombal’s early form of scientific surveying: sent 13 detailed questions to parishes, leading to rich data on the event and its effects.
  • Recognized as a contribution to the development of seismology.
• Intellectual and Theological Reverberations:
  • The disaster challenged prevailing theological optimism and led to philosophical debates.
  • Spotlight: Voltaire’s Candide
    • Used the earthquake to satirize Leibnizian optimism.
    • Tracy: “It was hard for people to reconcile that idea [best of all possible worlds] with the earthquake in Candide.” (37:52)
  • The event fueled rational, scientific inquiry and the growing Enlightenment movement, though the hosts stress this was an ongoing, complex process.

8. Controversies and Legacy

• Pombal’s Methods and Legacy:
  • Post-earthquake, Pombal was both lauded (for disaster response) and critiqued (for authoritarian overreach, use of crisis to advance personal and anti-Jesuit agendas).
  • Upon King José I’s death in 1777, Pombal fell from power and faced accusations of corruption; he died in 1782.
• Long-term Influence:
  • The Lisbon earthquake remains a foundational event in disaster management, urban planning, and philosophical thought.

Notable Quotes & Memorable Moments

• “Our guides would say that a site had been uncovered in the earthquake or damaged in the earthquake. ... this earthquake was obviously also a big enough deal in Morocco that people are still talking about it at historic sites 200 years later.”
  — Tracy V. Wilson (03:28)

• “There were three distinct periods of shaking over the course of about 15 to 20 minutes. And there has been debate about whether at least one of those was really an aftershock or if there were two different earthquakes very close together.”
  — Holly Frey (04:34)

• “Having been in some of those cities, that prospect is terrifying to me.”
  — Tracy V. Wilson, about the tsunami (08:04)

• “Bury the dead and feed the living.”
  — Attributed to Pombal, regarding the government’s immediate response (29:32)

• “It was hard for people to reconcile that idea [best possible world] with the earthquake in Candide.”
  — Tracy V. Wilson (37:52)

• Satirical take on the Enlightenment:

  • Holly: “Nobody was like, let’s start the Enlightenment, you guys.” (39:26)
  • Tracy: “I woke up this morning and I was in the Age of Reason. How about you?” (39:30)

Timestamps for Key Segments

• Introduction & Morocco Connections: 02:24–04:14
• Earthquake Science and Impact: 04:14–12:58
• Lisbon Before the Earthquake & Social Context: 17:44–23:35
• The Disaster in Lisbon: 23:35–26:37
• Government Response and Rebuilding: 27:33–31:43
• Seismological Surveys and Enlightenment Debates: 35:43–39:46
• Pombal’s Legacy: 39:46–40:54

Overall Tone & Takeaways

The episode combines sharp historical detail with the hosts’ accessible, conversational tone. Tracy and Holly stress how the earthquake was pivotal not just for its destruction, but for how it changed city planning, the science of earthquakes, and even European thought. They balance the scale of the devastation with fascinating stories about individual and governmental responses, philosophical challenges, and the rise and fall of consequential personalities.

For listeners, this episode offers a vivid, nuanced look at the Great Lisbon Earthquake—not just as a tragic event, but as a fulcrum of history, thought, and recovery that still shapes our world today.