1755 Lisbon earthquake

The 1755 Lisbon earthquake took place on November 1, 1755, at 9:20 in the morning. It was one of the most destructive and deadly earthquakes in history, killing well over 100,000 people. The quake was followed by a tsunami and fire, resulting in the near total destruction of Lisbon. The earthquake accentuated political tensions in Portugal and profoundly disrupted the country's 18th century colonial ambitions. The event was widely discussed by European Enlightenment philosophers, and inspired major developments in theodicy and in the philosophy of the sublime. The first to be studied scientifically for its effects over a large area, the quake signalled the birth of modern seismology. Geologists today estimate the Lisbon earthquake approached magnitude 9 on the Richter scale, with an epicenter in the Atlantic Ocean about 200 km west-southwest of Cape St. Vincent.

The birth of seismology

The Prime Minister's response was not limited to the practicalities of reconstruction. The Marquis ordered a query sent to all parishes of the country regarding the earthquake and its effects. Questions included:

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• how long did the earthquake last?
• how many aftershocks were felt?
• what kind of damage was caused?
• did animals behave strangely? (this question anticipated studies by Chinese seismologists in the 1960s)
• what happened in wells and water holes?

The answers to these and other questions are still archived in the Tower of Tombo, the national historical archive. Studying and cross-referencing the priests' accounts, modern scientists were able to reconstruct the event from a scientific perspective. Without the query designed by the Marquis of Pombal, this would have been impossible. Because the Marquis was the first to attempt an objective scientific description of the broad causes and consequences of an earthquake, he is regarded as a forerunner of modern seismological scientists.

Related Topics:
Tower of Tombo - Marquis of Pombal

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The geological causes of this earthquake and the seismic activity in the region continue to be discussed and debated by contemporary scientists. Some geologists have suggested that the earthquake may indicate the early development of an Atlantic subduction zone, and the beginning of the closure of the Atlantic ocean.

Related Topics:
Geological - Atlantic - Subduction zone - Atlantic

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See also: List of earthquakes

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