The Great Lisbon Earthquake of 1755
In 1755, Lisbon, Portugal held its position as one of the most beautiful and culturally developed cities in Europe. Lisbon boasted a population of approximately 275,000, placing as one of the most populated cities in all of Europe (Moreira, Nunes, & Kozak, 1998). But then the morning of November 1, 1755 arrived, bearing witness to one of the greatest disasters in European history: a huge earthquake, now estimated to have had a magnitude as high as 8.5 (Sanders & Zeilinga de Boer, 2005), caught the population of Lisbon, Portugal unawares. The death toll amounted to thousands, and there were also major effects on art and literature, science, religion, philosophy, government, and technology. This disaster left a legacy that was not soon to be forgotten.
Part I: The Events of the Disaster.
A total of three seismic shocks passed over Lisbon and, despite lasting only an innocent duration of ten minutes, inflicted catastrophic damage on the region (Moreira, Nunes, & Kozak, 1998). These shocks triggered a devastating sequence of tsunamis, some of which reached 20 feet high, and destroyed bridges while overturning ships (Ritchie & Gates, 2001).
The tremors from the earthquakes knocked objects, walls, and buildings to the ground. Flames from collapsed fireplaces and fallen candles – of which there were many, since it had been All Soul’s Day – were fanned higher by strong northeasterly winds, forming an inferno that swept through the city (Davis, 2002). The thick dust and smoke that was given off from the crumbling and burning buildings blocked the sunlight, casting the city into a brief period of darkness and flame (Ritchie & Gates, 2006). Accounts vary as to how long the fires lasted, varying from three days and nights (Davis, 2002) to more than a week (Sanders & Zeilinga de Boer, 2005). People found during this time that they had very few places where they could actually live.
Historians believe that approximately 30,000 residents perished within the first two minutes of the disaster. France, Switzerland, Northern Italy, and North Africa all felt the tremendous shaking, and even Fez and Mequinez of North Africa accumulated a significant death toll. Lakes in Scotland and Switzerland fluctuated by several feet following the earthquake (Pararas-Carayannis, 2000). At the time of the disaster, however, people were still clueless about the natural causes and warnings of an earthquake. Little knowledge had been discovered about the mysterious shaking of the ground. This lack of scientific and environmental knowledge and awareness led to failure in the ability to prepare for the deadly catastrophe, and contributed to the large death rate of the disaster. When the water of the River Tagus receded, for example, the citizens had no idea that the recession was a sign of a coming tsunami. Many, in fact, fled to the water’s edge for safety from falling buildings, or tried to escape by boat. Thus, when the waves came, all the escapees were swept away with them (Davis, 2002).
Part II: The Effects of the Disaster.
The people of the time leaned more towards religious explanations for the disaster instead, to explain what they could not understand. Even before the earthquake, religion – especially the Society of Jesus, or the Jesuits – was strong in Portugal. The Society’s Inquisition had been widespread and merciless, and increased in intensity after the Lisbon disaster. The Jesuits, those of the Society of Jesus, believed it was God’s punishment for the sins and sinners of Lisbon, and thus opposed the reconstruction of the city that began after the earthquake. They and other devoutly religious people said it was everyone’s duty first and foremost to repent and rid the city of heretics (Sanders & Zeilinga de Boer, 2005). The French philosopher Jean-Jacques Rousseau thought the disaster was proof for his theory of natural man, where God was punishing the population for not living in the trees among nature (LeVay & Sieh, 1998). Many other religious myths or beliefs arose from various religious factions, including one Sebastianist who claimed to have foreseen the earthquake (Sanders & Zeilinga de Boer, 2005).
All the libraries and museums in the city were burnt to the ground, with devastating effects on the art and literature, and thus history and culture, of Portugal. Several buildings, such as the Opera House and the Patriarchal, were spared by the earthquake but enveloped in flames (Moreira, Nunes, & Kozak, 1998). Both the royal palace and the palace of the Marques de Lourical were destroyed, along with hundreds or more of paintings by Rubens, Correggio, and Titian, and other priceless artwork. The palace of the Marques de Lourical had had an invaluable library of 18,000 books (Davis, 2002), while the royal palace had had a precious 70,000-volume library (Pararas-Carayannis, 2000). Archives of many famous works, including early Portuguese explorers’ maps and charts, were lost in the libraries’ destruction. Whatever the time span of the fires, most historians agree that they wreaked some of the greatest destruction brought upon the city (Sanders & Zeilinga de Boer, 2005).
The destruction of so many valuable historical and cultural items affected art and literature, but the catastrophe itself also had a major impact on the thinking of authors of the day. The Age of Enlightenment had been in full swing when the 1755 earthquake struck, taking away much of the age’s momentum. The destruction inspired writers such as Rousseau previously described, and the French philosopher Voltaire. The disaster confirmed Rousseau’s belief in his theory of natural man, but also confirmed Voltaire’s growing doubt in the fallacy of the idea of “universal good”. Voltaire was roused into writing his Poème sur le désastre de Lisbonne a year after the earthquake, and the famous Candide in 1759, a satirical work. In addition, the 1755 disaster inspired the creation of music such as the heart-wrenching Portuguese fado (Portuguese for “fate”) songs. “Those traditional songs speak of mankind’s fragile existence, always at risk because of the destructive powers beyond human control” (Sanders & Zeilinga de Boer, 2005).
Portuguese politics and the government of the day were affected by the disaster as well. Under King Joao V, a deeply religious man, the Roman Catholic Church became extremely powerful in Portugal in the early 18th century. He appointed Sebastiao José de Carvalho e Mello Minister of War and Foreign Affairs in 1749, the appointment of which his son and heir José I approved of upon his death in 1750. Carvalho’s influence climbed until he was named Marquês de Pombal two decades later. In the aftermath of the disaster, the indecisive king José I let Pombal temporarily take dictatorial charge of the situation and country. Pombal used his power to protect and restore the country first, by employing soldiers to protect the city from looting, setting up places for survivors to live, burying the dead in the sea to prevent disease outbreak, creating places where food and clean water could be obtained, and working with architects for the reconstruction of the city. Afterwards, however, Pombal used his power to weaken the power of the church – partly because of dislike of their opposition to Lisbon’s reconstruction, and partly because of their resistance to Portuguese control of a valuable Paraguay colony. Jesuits and many aristocrats resented his power over the king and country, the matter of his low birth also irking them. The dispute culminated in the deterioration of aristocratic and church power, and the execution of many and the exile of all Jesuits. The reign of Pombal was brought to a halt by the 1777 death of the king and the ascension of his nobility and church-sympathetic daughter Maria to the throne. He was declared a criminal and died five years later. Although Pombal’s life ended in disgrace, however, many of the effects of his 22-year-long rule remained long after him (Sanders & Zeilinga de Boer, 2005).
Although the earthquake brought about much turmoil for Lisbon, a necessary new science sprang into prominence in its aftermath. This science, termed seismology, centralized on the study of tectonic plates. Although the idea that earthquakes and other geological disasters had predictable physical precursors was proposed in the time of the Ancient Romans, the notion was not seriously acknowledged until the 18th century when the Lisbon quake sparked popular interest. However, this concept was, at the time, a subject of much dispute, particularly considering the coincidental dating of the Great Lisbon Earthquake in occurrence with All Saint's Day (LeVay & Sieh, 1998). Despite the controversy, a methodical system was eventually developed, in which data concerning the time and location of later earthquakes were recorded and utilized to detect patterns in the occurrence and location of earthquakes (Pararas-Carayannis, 2000).
Cambridge geology professor John Michell published a report in 1760 which detailed his theory of the origin of earthquakes, focusing on wave propagation, and concluded that the Lisbon earthquake originated in the eastern Atlantic (Sanders & Zeilinga de Boer, 2005), 200 kilometers southwest off of Cape St. Vincent (Moreira, Nunes, & Kozak, 1998) in a region named the Azores-Gilbratar fracture zone (Pararas-Carayannis, 2000). This zone is notorious for large earthquakes, as the zone marks the border of tectonic interaction between the Eurasian and African plates (Pararas-Carayannis, 2000). Undersea quakes have been recognized as the catalyst of the tremendous tsunamis of 1755, and scientists now know that the actual earthquake was caused by an undersea session of heightened tectonic activity. In present day, seismologists utilize scientific equipment and knowledge to predict and analyze earthquakes. Michell is considered to be one of the "fathers" of seismology due to his reliable methodology and results in his research on the Lisbon earthquake (Sanders & Zeilinga de Boer, 2005). The Great Lisbon Earthquake had at least one positive effect: it pushed the people of the time to a greater era of scientific discovery.
Part III: The Influence on Technology.
As with the lack of scientific and environmental knowledge, the lack of sophisticated technology contributed to the great devastation of the Lisbon Earthquake. Prior to the earthquake, the streets of Lisbon were foul and narrow, hidden in shadows. The disadvantage of narrow streets were realized too late when people found nearly all their escape routes blocked by fallen rubble (Sanders & Zeilinga de Boer, 2005). As for seismic instruments, the few early devices available for earthquake measurements – seismographs – were slow and unable to take time into account: Nicholas Cirrillo measured the amount of ground motion in the 1731 Naples earthquakes by using pendulums, presumably a rather inaccurate process (Bolt, 1993). There were not any seismic instruments at all for determining shock origin then.
According to the Merriam-Webster Dictionary, technology is “the practical application of knowledge especially in a particular area”. There were many such practical applications in the aftermath of the disaster. Having learned their lesson the hard way, the Portuguese rebuilt Lisbon with wider streets. “In both Europe and America the earthquake encouraged the search for scientific reasons for natural phenomena” (Sanders & Zeilinga de Boer, 2005). As mentioned previously, the English geology professor John Michell was inspired by the Lisbon earthquake to invent a method for determining earthquake origin, where the directions of waves in different areas were plotted as lines on a map and extended until an intersection – the origin – was found (Sanders & Zeilinga de Boer, 2005). On top of this invention, Michell was further inspired in 1760 to make the first attempt in history, though erroneous, to calculate the speed of earthquake waves. The Lisbon earthquake, along with others, also encouraged the creation of the Italian Luigi Palmieri’s mid-19th century seismoscope sismografo elettro-magnetico that was able to record the time of earthquakes, and the English John Milne’s instruments that recorded ground shaking as a function of time (Bolt, 1993).
An innovative transformation took place in the field of Lisbon's architectural technology, too. Many buildings were leveled by the devastating earthquake, fire, and tsunami, and thousands of Lisbon's residents were left homeless. In addition, the approaching winter contributed to the pressing need and urgency for new housing. The Marquês de Pombal, an official overlooking the recovery of Lisbon, gave order for the new, reconstructed city center to be built on a firm, geometrical plan for greater organization. Also, buildings along the street from the Praca do Comercio to the Praca Rossio were built unvaryingly as three storeyed with tiled roofs and eave-corners turned upward. The height and width of the buildings were constant, thus the uniformity of the construction of the houses allowed for rapid reconstruction. The residents of Lisbon benefited from this speedy reconstruction as they sought shelter against the incoming chill. Today, this building style is known as estilo Pombalino, named after Marques de Pombal, and appears to resemble simplistic baroque (Whitfield, 2005).
Not only did the Lisbon earthquake spur technological advancements directly after the disaster, it instigated modern study as well. Because of its seismic history, the area near the Gorringe Bank was first believed to be the origin of the 1755 earthquake (Sanders & Zeilinga de Boer, 2005). Recent seismological studies using modern technology have shown, though, that the origin of the earthquake was along the immense East Atlantic rise (Bolt, 1993), a formerly unknown fault, and caused by a rupturing in the fault. The discovery of this new fault led to its being named after Marquês de Pombal, one of the leaders of Portugal in the aftermath of the Lisbon earthquake (Sanders & Zeilinga de Boer, 2005).
Part IV: The Natural Record.
Portugal’s earthquake left its legacy in the natural world in addition to the technological one. The history of previous earthquakes and fault ruptures in a certain area can be used to figure out the probability of future such occurrences, and the extent of seismic hazard the area poses. Fault scarps are often formed in earthquakes of magnitudes greater than 6.5. Studying the condition and form of fault scarps – a field known as tectonic geomorphology – can provide estimates of when the earthquake that produced it occurred (Brumbaugh, 1999). Recent studies have revealed that the seafloor near the Marquês de Pombal fault is raised by heights as great as ten meters in places, and that it was this rupturing that caused the Lisbon earthquake of 1755. The elevation of the Gorringe and Ampere banks southwest of Lisbon has also been found. This evidence, coupled with cracks in the ground in Lisbon, has allowed seismologists to estimate that the earthquake had a magnitude as high as 8.5 (Sanders & Zeilinga de Boer, 2005).
The flood water that crashed onshore receded and carried sediment and plants from the region’s ground back to the river and sea. This recession of water contributed to the erosion on the shores of Lisbon, although the effects were not seriously detrimental to local ecosystems on a large scale. However, the effects of the flood can still be seen from disturbed soil layers from the 1700’s (Weaver, Wynn, Kenyon, & Evans, 2000).
Patterns of disturbances can be found in the sediment layers in beds of lakes and other bodies of water. These layers are rich in the carbon from plant decay (Brumbaugh, 1999), and ideal for carbon-dating. Carbon-dating the vegetation found in layers cut by a fault provide further information on when faults moved, and consequently, when earthquakes occurred (Prager, Williams, Hutton, & Synolakis, 2000). Identification of a recurrence interval may also be possible (LeVay & Sieh, 1998). Earlier sedimentary records in the Lisbon region revealed that events such as the Lisbon earthquake occur around once every 1,500 to 2,000 years in the Gulf of Cadiz (Weaver, Wynn, Kenyon, & Evans, 2000).
Some trees also recorded the occurrence of the flood within their annual rings due to their affected growth in wet soil. Trees in a flood area typically produce abnormalities in ring formation, such as a decrease in wood fiber and development of early wood vessels, although continuous inundation is required for a clear record on the ring. The flood resulting from the Lisbon earthquake did not last for a significant period of time, thus the effect on the trees was not thoroughly detailed (St. George & Nielsen, 2002).
The Great Lisbon Earthquake of 1755 was a landmark in a period of momentous change. Catching everyone completely unawares, this disaster struck the world to the heart. Starting on the morning of November 1st, 1755, a sequence of earthquakes rocked the city of Lisbon, Portugal. The earthquake caused an unrelenting fire in the city, which consumed buildings, artwork, and lives alike. The shocks of the earthquake generated tsunamis as well, which flooded the region, overturning ships, destroying bridges, and inflicting catastrophic damage. This event, which took tens of thousands of lives, became the inspiration for artists, writers, scientists, philosophers, politicians, and musicians of the time. Famous works, such as Voltaire’s Candide included significant references to the earthquake. The founding of the new science of seismology and a new architectural style were also inspired by this disaster. The mark of this 1755 earthquake has left a tell-tale legacy on the natural world, too. All in all, the destruction to the city of Lisbon was complete. The once-proud city was humbled before the power of nature, lying in ruins where magnificent buildings once stood. It was a cruel dash of water in the faces of the Portuguese people who, still in the middle of the Age of Enlightenment, had happily believed in the good of the world. The echoes of the Great Lisbon Earthquake of 1755 would resound throughout the ages, being heard well into the future.
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