The 1755 Lisbon Earthquake

On the morning of November 1, 1755, All Saints' Day, an earthquake centered beneath the Atlantic seabed southwest of Portugal shook Lisbon for several minutes while many residents were at Mass. Within about 40 minutes a tsunami swept up the Tagus estuary, and fires burned through the ruined city for days. One of the richest capitals in Europe, the seat of a global trading empire, was largely destroyed. The disaster shook European thought as well as its buildings. Voltaire answered it with a poem and later with Candide, the young Immanuel Kant wrote some of the first scientific essays on earthquakes, and Portugal's chief minister rebuilt the capital with some of the earliest earthquake-resistant buildings anywhere.

The epicenter is not known precisely, because the quake struck long before seismographs. Most studies place it a few hundred kilometers west-southwest of Cape St. Vincent, along the boundary between the Eurasian and African plates that runs east from the Azores toward the Strait of Gibraltar. Modern estimates of its magnitude range from about 8.5 to 9.0. Shaking was felt from Finland to North Africa, and the waves reached Morocco, southern Spain, Madeira, Britain, Ireland and the Caribbean. In Lisbon the tsunami surged over the riverfront at the Terreiro do Paço, the royal palace square, where people had gathered on open ground to escape falling buildings. Algarve towns such as Lagos were battered by waves estimated at 15 meters or more, and Moroccan ports from Tangier to Agadir also suffered.

Deaths in Lisbon are usually put at 30,000 to 40,000, and estimates for the whole region, including Spain and Morocco, reach about 50,000, though historians have argued for both lower and higher figures. The royal palace, its library, churches, archives and the new opera house were lost. Sebastião José de Carvalho e Melo, later the Marquis of Pombal, directed the response, his approach often summed up as "bury the dead and heal the living." His engineers laid out the Baixa on a grid of wide streets and built with the gaiola pombalina, a flexible timber cage set inside masonry walls. Pombal also sent a questionnaire to every parish about the shaking, the aftershocks and the behavior of the sea, an early systematic survey of an earthquake that seismologists still study.

• Morocco
  Where the Atlas Mountains meet the Atlantic and the Sahara also struck
• Spain
  The heart of Iberia, from Moorish palaces to sun-soaked coasts also struck
• The 2004 Indian Ocean Earthquake and Tsunami
  The magnitude 9.1 Sumatra–Andaman earthquake and the deadliest tsunami in recorded history, which killed about 228,000 people in 14 countries another great tsunami
• Atlantic Ocean
  The world's second-largest ocean and great highway of history epicenter in
• The Tectonic Plates
  The seven great slabs and dozens of smaller ones that make up Earth's moving shell Eurasian–African plate boundary
• Portugal
  Europe's Atlantic edge, from port wine valleys to ocean-going history located in
• The Strait of Gibraltar
  The 14-kilometer gap between Europe and Africa that is the Mediterranean's only natural link to the Atlantic on the plate boundary leading toward
• The Mid-Atlantic Ridge
  The 16,000-kilometer undersea mountain range where the Atlantic Ocean is still being born on the plate boundary running east from
• Lisbon
  Portugal's capital, a city of seven hills above the Tagus struck
• The Iberian Peninsula
  A high, dry tableland walled off by the Pyrenees struck