When Lisbon experienced an earthquake on November 1, 1755 (sometimes called the Great Lisbon Earthquake), it was not an unique event for the city. Previous earthquakes had punctured Portugal’s capital in 1321 and 1531. The 1755 quake, measuring an estimated magnitude of 8.5-9.0 Mw, however was qualitatively worse because of the widespread nature of the damage and the ongoing repercussions.
Lisbon Pombaline Downtown street plan [Source: www.travel-in-portugal.com]
No sanctuary in the churches
The focus of the earthquake in Lisbon was on the city centre where the churches, it being All Saints Feast Day, were packed with the pious. The churches’ antiquated construction methods, leaving them incapable of withstanding violent movement of the earth, guaranteed a high death toll of the attendees. The foundations of the churches, built on soil liquefaction, only enhanced their vulnerability to violent earth movements [‘November 1, 1755: The Earthquake of Lisbon: Wrath of God or natural disaster?’, (David Bressan), Scientific American, 01-Nov-2011, www.blogs.scientificamerican.com].
Earthquake decimation of one of the city churches
Fire on the heels of five-metre wide fissures in the earth
Fires were an immediate consequence of the earthquake. Some of these were firestorms triggered by the massive earth tremor, and some were a direct result of it being a day of religious significance. Scattered through the churches were lit candles in observance of the holy day, the convulsions tipped the candles over, igniting the displays of flowers and spread the fire in all directions. Buildings that managed to escape the destruction of the earthquake often were subsequently consumed by the firestorms [‘1755 Lisbon earthquake’, Wikipedia, http://en.m.wikipedia.org].
Tsunami triple-whammy
Because the earthquake hit the central part of the city, many Lisboeta❅ who survived the initial three-and-a-half minute-long megashock made for the docklands and the harbour. Tragically what was thought a safe move proved a fatal one for many. Just 40 minutes after the quake hit Lisbon, it was followed by a (20 foot high) tsunami which pulverised the shoreline and engulfed the Rio Tejo (Tagus River), sending the huddled crowds on the docks scurrying for their lives. The fires and the tsunami compounded the calamity of the seismic event and sent the death toll skyrocketing◘.
‘Ripples’ of the tidal wave
The 1755 tsunami was a teletsunamic event with the generated tidal waves crossing the vast ocean. The mid-eastern Atlantic tsunami which hit Lisbon with such force, had amazingly far–flung ramifications. The tsunami was felt literally around the known world. Within an hour it had reached Cornwall on the south coast of England and Galway in Ireland.It was felt as far afield as Finland, North America, Barbados and Martinique in the West Indies and maybe even in Brazil.
Fallout in the region
The devastation caused by the earthquake, fires and tsunami was not confined to Lisbon. Other parts of southern Portugal (the Algarve) suffered. Spain too, especially Cadiz which was hit by an even more massive tsunami (65-feet high), lost as much one-third of its population. Parts of Morocco also bore the brunt of the cataclysm with possibly up to 10,000 of its population perishing as a result [Pereira, Alvaro S. “The Opportunity of a Disaster: The Economic Impact of the 1755 Lisbon Earthquake.” The Journal of Economic History 69, no. 2 (2009): 466-99. www.jstor.org/stable/40263964].
Copper engraving, 1755
Casualty count
There have been widely diverse estimations of the human toll from the 1755 earthquake—ranging from 10,000 to anything up to 100,000. Economist AS Pereira has noted how unreliable estimates are…owing to the lack of dependable data on the Portuguese population prior to 1755 and compounded by the public authorities’ decision to swiftly bury the corpses before there was a chance of disease and plague taking root (Pereira). Pereira’s own estimate based at data from surveys in 1757 put the casualties at 30 to 40 thousand out of a possible 200,000 population at the time. Added to this is the up to 10,000 who died in Morocco from the catastrophe○.
The devastation and reconstruction It is estimated that around 85% of Lisbon’s buildings were destroyed by the earthquake and associated phenomena. Two-thirds of the city was made uninhabitable. Among the carnage, in addition to the churches already mentioned, were famous libraries and palaces. Also lost was the city’s new opera house Ópera do Tejo and many examples of distinctive 16th century Manueline architecture. The Palácio Real Ribeira was a casualty, lost were some 70,000 volumes of work including tracts on voyages of early explorers such as Vasco da Gama and art works by Titian, Corregio and Rubens, and so on.
Rua Augusta in the Baixa Pombalina [Photo: www.weheartlisbon.com]
The reconstruction was put in the hands of Sebastião José de Carvalho e Melo, later bestowed the title of Marques de Pompal by King José I (Joseph I). Pompal’s elevation to sole control of managing the reconstruction and his competence in carrying through the plan allowed him to wrest the political reins of Portugal away from the old aristocracy. Ordinary citizens were pressed into the immediate task of clearing the debris so that Pompal could commence the long and slow task of rebuilding the city largely from scratch. Erected were new, large squares, widened streets and rectilinear avenues. An entirely new lower town Baixa Pombalina (Downtown district) was created. The Pombaline buildings proved to be radically innovative, being among the earliest seismically protected constructions in Europe.
Embryonic signs of the science of seismology
There is one important factor which separates the 1755 quake from those preceding it. In its aftermath Pompal coordinated systematic surveys in the nature and course of the earthquake. The preservation of data collected and archived at the time has allowed modern seismologists to better analyse the natural event and its genesis. Thus, in a very rudimentary but pioneering way, this has contributed to the development of what has become the science of seismology and the practice of earthquake engineering (‘Lisbon earthquake’, Wiki).
The phenomena, a boost to scientific enquiry, also caused religious rumblings at the time. Many in staunchly Catholic Portugal wondered if the degree of devastation was a manifestation of divine judgement, God’s wrath on flawed mortals. Discussions of theodicy and other philosophical questions abounded (Bressan).
The earthquake‘s effects on the Portuguese economy
The catastrophic 1755 event presented Pompal with the opportunity to reform the country’s economy and to some extent reorganise society. Pereira‘s work has looked at the cost of the devastation to Lisbon. As he has pointed out, Lisbon at the time was “staggeringly rich” courtesy of the plunder of its colonies in Africa and the New World. The city was awash with huge stores of gold bullion, jewels and expensive merchandise✧. The economist estimated the direct cost of the earthquake at between 32 and 48% of Portugal’s GDP. Another consequence was prices and wages volatility, albeit this was only temporary (Pereira).
Pompal’s reforms
To counter the deterioration in the country’s public finances✬, the Marques introduced several economic reforms and institutional changes. The state bureaucracy was streamlined and the treasury was reformed with the advent of a new tax system. Pompal’s mercantilist policies revamped the Portuguese economy. Pompal’s policies long-term had the effect of enhancing the centralist orientation of the economy and reduced Portugal’s dependence on its main trading partner Britain (Pereira).Seismologists have speculated as to whether the Lisbon Earthquake remotely triggered two other earthquakes—in Cape Ann (near Boston, Mass) and Meknes, Morocco—which followed it by just 17 and 26 days respectively [‘1755 Cape Ann earthquake’, Wikimili, The Free Encyclopedia, http://wikimili.com].
Cape Ann Earthquake (Woodcut illustration) 
Endnote: The “first modern disaster”Endnote:The “first modern disaster”
The cataclysm event in 1755, so redolent of apocalyptic imagery, prompted theologians, scientists and philosophers like Voltaire and Rousseau to conjecture—was causation natural or divine? It’s “modern-ness” lying in several innovative aspects of the phenomena: a concerted and systematic attempt at “crisis management”; among the “first provisions for urban disaster mitigation and earthquake resistant building design“; an attempt to “investigate and record the effects of the earthquake throughout the affected areas”, anticipating the science of modern seismology [‘From 1755 to Today—Reassessing Lisbon‘s Earthquake Risk’, (Drs Guillermo Franco & Bingming Shen-Tu), AIR Currents, (15-Jul-2009), www.air-worldwide.com; Bressan].
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❅ as residents of Lisbon are sometimes called
◘ given that the earthquake’s epicentre was in the Atlantic Ocean some 350-400 km from Lisbon, it is plausible that the fires and tsunami caused the greatest havoc and devastation (Franco & Shen-Tu)
○ possibly the death toll cited for Morocco on the 1st of November has been conflated with the Meknes earthquake on 27th November 1755 which also was reported as having had 10,000 victims
✧ in India House alone the holdings in diamonds amounted to 11-12 million cruzados
✬ in the wake of the earthquake Portugal’s colonial ambitions were stalled, which would have added to the economic decline