It was one of the most destructive earthquakes on record and, quite possibly, changed the course of European history.
The epicenter of the earthquake was in the North Atlantic about 200 kilometers southwest of the Portuguese coast and geologists now estimate the magnitude at almost 9 on the Richter scale. There was no warning when the tremors came in three devastating jolts on November 1, 1755 (All Saint's Day) beginning at 9:30 in the morning (local time). Although the earthquake subsided after only ten minutes, the devastation 
was only just beginning.
In the city of Lisbon, fires raged out of control for days and destroyed large sections of the city. People fleeing the city attempted to escape any way that they could including aboard ships that were still moored on the Tagus river. Unfortunately, the tsunami that followed the earthquake battered the coast and rushed up the river thirty minutes after the tremors ended. Many of the low-lying areas were swamped by three great waves that washed people, buildings, and ships out to sea. The maximum height of the waves was later estimated at thirty meters in some places. Boats were capsized, buildings were drenched, and almost all the coastal areas of Algarve were heavily damaged.
Estimates vary concerning the total loss of life on that fateful day and range from 60,000 to 100,000. Lisbon, which had been one of the most heavily populated cities in Europe, lost as many as 90,000 out of a total population of 275,000 and countless more were left homeless. Over eighty percent of all the buildings in the city were destroyed including priceless architecture and artwork. The Royal Hospital burned to the ground with hundreds of patients inside. Although the worst of the damage was in Portugal, there was also heavy loss of life in the Moroccan cities of Fez and Mequinez. The tremors were felt as far away as Spain, France, Switzerland and Italy.
While earthquakes were hardly uncommon in the region, nothing of that magnitude had ever been experienced before. Portuguese troops were overwhelmed with the task of clearing the rubble and dealing with the thousands of corpses left behind. They also dealt harshly with looters (with thirty-four public executions to deter others). To prevent the spread of disease, many corpses were loaded onto barges and buried at sea (to which the Church objected). Able-bodied citizens were drafted to aid in the reconstruction work.
Word about the earthquake spread and countries across Europe promptly sent aid (making it the first truly international relief effort). Due to transportation delays, months passed before that aid could reach Lisbon. Portugal's economy was strained to the breaking point dealing with the expense of feeding and housing the thousands left homeless by the earthquake. In discussing the aftermath of the disaster, the Marques de Pombal, then Portugal's chief minister, reportedly made the famous statement that their main task was to "bury the dead and to feed the living" (actually it was another prominent noble who said it first but Pombal, ever the politician, made the phrase his own).
The earthquake had a profound effect on European cultural thinking. Theologians agonized over why God had permitted such a disaster in a predominately Catholic country (and on a holy day no less). Many proclaimed that it was due to the "wrath of God" and further disasters were predicted. Philosophers across Europe debated the implications of what happened. Voltaire wrote a controversial work about the earthquake titled Poem on the Lisbon Disaster in which he openly condemned prevailing views about the nature of good and evil. Using the calamity as an example, he introduced readers to his own pessimistic philosophy (he would expand on this further in his better-known Candide). Early researchers including Immanuel Kant and the Marques de Pombal himself studied the Lisbon earthquake in depth and their published findings are considered to mark the beginnings of the modern science of seismology.
The psychological impact of the earthquake is harder to determine but the Great Earthquake certainly had a lasting effect on the survivors. While the Royal family escaped unharmed (largely by chance since there were spending the holiday away from Lisbon), the Ribeira Palace was completely destroyed. King Joseph I never really recovered from the devastation and, for him, the trauma took a most peculiar form. Until his death in 1777, he would never allow himself to be inside a walled building and, at his urging, the entire royal court was moved to the "Real Barraca" (Royal Tent), a collection of tents and pavilions in the hills of Ajuda. It was there that he presided over the rebuilding of Lisbon for the rest of his life. Only during the reign of his daughter, Maria I, was the new Ajuda National Palace built on the site where the Royal Tent had stood.
Restoring Lisbon to its former glory took decades and the rebuilt sections of the city marked the first examples of earthquake-proof architecture. The designs for the new buildings were tested in a most intriguing way. Scale models were built and troops were marched around them to simulate the effects of an earthquake (a low-tech solution to a practical problem). There were later earthquakes in the region with additional loss of life and property damage but nothing to the extent of what gone before (so far).
While many other natural disasters have occurred since the Lisbon earthquake, it remains a grim reminder of the enormous loss of life that can occur. Improvements in transportation, communication and medicine may have enabled the rapid deployment of relief efforts but burying the dead and feeding the living is still a heartbreaking task for aid workers and survivors alike.
Click here for an eyewitness account of the earthquake.
