The Lisbon earthquake of 1531 and Gil Vicente's rebuke to the friars

Garcia de Resende, a poet and royal secretary, began his account with a flash like lightning. Thunder followed, and then a great earthquake, “so great that it made people faint”. It struck between four and five in the morning of Thursday 26 January 1531, when most of Lisbon was asleep. It lasted, Resende wrote, about as long as it takes to say the Creed; any longer and everything would have fallen.3 sources3 sources

In the city, royal palaces were badly damaged. The rooms of Queen Catarina, a sister of the Emperor Charles V, crumbled, and so did those of the king's brother, Prince Henrique. In the house of a Valencian lady, Juana de Acuña, every room fell except her own bedroom, and four women of her household were killed. A street the letter calls the rua dos hornos, the street of the ovens, sank.1 source1 source

Up the river it was worse. At Azambuja not one house was left standing, according to a letter sent from Portugal to a Castilian nobleman. The ground shook again at seven, and once more after midday.2 sources2 sources

It was the first Portuguese earthquake whose damage was written down town by town, which is why seismologists can still map it. It also brought out something uglier. In Santarém, friars preached that God had sent it to punish Portugal's sins, and the town's New Christians, the descendants of forcibly baptised Jews, went into hiding. Gil Vicente, the court playwright, gathered the friars in a cloister and told them they were wrong.3 sources3 sources

João III had been king since 1521, and not all his Christian subjects were trusted equally. In December 1496 his father, Manuel I, had ordered the Jews of Portugal to leave, then made leaving almost impossible; in 1497 most were baptised by force. Their descendants were called New Christians, cristãos-novos, to set them apart from Old Christians.2 sources2 sources

The label could be deadly. In April 1506, with Lisbon hit by plague and hunger, a mob urged on by two Dominican friars hunted New Christians through the city for three or four days. Estimates of the dead run from about 1,000 to 4,000. Lisboeta tells the story of the expulsion and the massacre in a separate article.2 sources2 sources

João III wanted an Inquisition on the Spanish model, with inquisitors chosen by the crown. He opened negotiations with Rome around 1527, and the popes held out for years. So when the earth shook in 1531, the question of what to do with the New Christians was already on the king's desk.1 source1 source

One of the earliest descriptions of the damage is an unsigned letter from Portugal to Fadrique Enríquez de Rivera, Marquis of Tarifa, which a Burgos printer published in 1531 in a broadsheet called Traslado de dos cartas. It names the Ribeira palace on the waterfront and the churches of Nossa Senhora da Escada and São João da Praça among the buildings shattered. Statues fell in the monastery at Belém; the monastery and the tower beside it cracked but stood. The Carmo and the cathedral got off lightly.1 source1 source

The letter is not a neutral report. The historian Marta Albalá Pelegrín calls it tabloid-like, keen on signs and portents, and it takes a close interest in which Castilians in the queen's service died and who survived. Many at court, it says, slept in their day clothes so they could run.1 source1 source

More than two centuries later, Joachim Joseph Moreira de Mendonça, writing after the 1755 disaster, put a number on it. The 1531 shock, he wrote, brought down many churches and palaces and more than 1,500 houses, and left almost all the rest uninhabitable. He reckoned 1,500 houses were a quarter of the city as it then was, and argued that, measured against the size of Lisbon, 1531 had done more damage than 1755.1 source1 source

Nobody counted the dead. Resende wrote only that “countless people died”, and sources from the period, Sá and colleagues note, give anything from 1,000 to 30,000 in Lisbon. A 1988 study of the documents by Henriques and colleagues estimated that a tenth of the houses collapsed and 2 per cent of the population died. Most later studies settle on about 1,000 dead.4 sources4 sources

In 2018 Sá and colleagues rebuilt the city of 1531, its geology and its houses, in a computer model. Their simulation gave 46 deaths at the moment of the shock, 158 to 397 in the first week and about 1,000 in all. The worst damage fell on the low town near the river. A 2021 review notes that Baptista and colleagues had already blamed soft, infilled ground there, which amplified the shaking, and weak foundations.2 sources2 sources

Lisbon was not the centre of the shaking. Seismologists put the epicentre somewhere between Vila Franca de Xira and Azambuja, upstream on the Tagus. Justo and Salwa assigned intensity IX, on a scale that tops out at XII, along more than 70 kilometres of the valley, from Lisbon to Santarém.2 sources2 sources

The letter to Castile runs through the river towns. At Vila Franca forty houses were said to have sunk, burying thirty people. At Castanheira sixty died. In Santarém the houses along the river were flattened, so that the king and queen could not go there, and Almeirim, across the river, fared no better. At Tancos, further upstream, the princess and her ladies escaped through the windows in their underclothes when the prince's residence fell. In Setúbal the houses of a marquis and of his son split open.1 source1 source

At Almeirim, Resende wrote, the ground cracked and opened holes, and water and sand came out that stank of sulphur; heavy rain in the following days filled the holes and they were never seen again. Modern seismologists read this as liquefaction, when waterlogged sand loses its strength and spurts to the surface. It was also reported at Vila Franca, Azambuja and Santarém, and on the south bank, at Setúbal and Alcácer do Sal, water poured from cracks in the soil.2 sources2 sources

Some tales grew in the telling. The letter has a fountain running with blood, and Mendonça heard that whole villages had been swallowed. He did not believe it, since no place in the kingdom kept any such tradition. Justo and Salwa likewise rejected reports of damage far from the epicentre.3 sources3 sources

Something happened to the river. Mendonça wrote that the Tagus uncovered its bed as its waters ran towards the banks, and that ships were lost. Reports summarised by Teves-Costa and colleagues describe boats lying about 90 metres from the shore left dry, or touching the riverbed with their keels. The letter to Castile has ships rising to the sky and the Tagus splitting in two.3 sources3 sources

Baptista, Miranda and Batlló gathered these accounts in 2014. Witnesses reported large waves, damage to boats anchored in the upper estuary and changes to the riverbed. They proposed that the quake lifted part of the riverbed, most probably along the Vila Franca de Xira fault, and modelled the wave that would follow. Their model reproduced the flooding described in the inner estuary but gave only minor flooding in downtown Lisbon.2 sources2 sources

So the answer is a qualified yes: a tsunami inside the estuary, which the Euro-Mediterranean Tsunami Catalogue lists as definite, not an ocean wave like that of 1755. In Santarém, Gil Vicente reported, some were telling the people that the sea would rise on 25 February.3 sources3 sources

The ground had warned them. Strong tremors began around 7 January across the kingdom, and many people moved out of the towns into the fields. The historian Maria de Deus Manso argued that this saved lives when the main shock came.3 sources3 sources

After the 26th the shaking went on. Resende counted further strong shocks, one of them on a later Thursday before dawn that was as frightening as the first, and wrote that the land trembled for fifty days and, more gently, for a whole year. Mendonça wrote that the king and queen camped in the open, as did the people of Lisbon. When it was over, the king went to a monastery at Azeitão to commend himself to God, and Gil Vicente's letter found him at Palmela, south of the Tagus.4 sources4 sources

Because so many towns described their damage, 1531 can be mapped. Moreira, in 1985, estimated intensities at 18 places, the first such map for a Portuguese earthquake. Justo and Salwa added a few records from Portugal and Spain and judged the maximum intensity probably X on the MSK scale.3 sources3 sources

The likely source is the Lower Tagus Valley fault zone, a set of faults mapped for about 80 kilometres along the valley. In 2021 Carolina Canora and colleagues dug a trench across it at Alviela, near Santarém. Sediments laid down roughly between 1450 and 1635 had been broken by a surface rupture, most probably that of 1531. Their ground-motion models fitted the recorded damage best with a rupture about 40 kilometres long and a magnitude of about 7.1 source1 source

Not everyone agrees on the size. Estimates since 2001 run from about 6 to 7.4, depending on the method and on how much weight is given to the damage in Lisbon, which looks too severe for the distance unless the ground or the buildings made it worse.3 sources3 sources

The valley's last large earthquake, on 23 April 1909 near Benavente, was smaller, about Mw 6.0, and killed 46 people (47 in another count). Sand and water again spouted from cracks in the flood plain.2 sources2 sources

Many people in 1531 read an earthquake as a message from God; Resende himself blamed “our sins”. A broadsheet printed in Burgos ended with a song calling on Christians to burn and destroy “any damaging sect”. In Santarém, as Gil Vicente told the king, the friars went further.3 sources3 sources

The second claim was a forecast: as the earthquake left, another was already on its way, bigger still, and it would come on Thursday an hour after midday. “The people believed this so much,” Vicente wrote, “that they went out at once to meet it in the olive groves, and they are still waiting for it there.”1 source1 source

Vicente does not record which sins the friars named, but the end of his letter leaves little doubt about who was meant. After the first sermon, he told the king, “the New Christians disappeared and went about dying of fear of the people”. It was 25 years since the Lisbon massacre of 1506, which friars had also urged on.2 sources2 sources

Gil Vicente was the leading playwright of the Portuguese court, whose plays, among them the Auto da Barca do Inferno of 1517, were written for court occasions. In 1531 he described himself as “so near death”. He asked the friars to meet him in the cloister of the convent of São Francisco in Santarém, and there he gave them a speech, which he then wrote out for the king.1 source1 source

His first argument was about nature. God, he told them, made two worlds: heaven, which is perfect and lasting, and this one, built on purpose to be unstable, so that everything here has its contrary. Against beauty comes sickness, against strength old age, against tall trees the storm, and against fine temples and sumptuous buildings the earthquake. Writers recorded the disasters that were miracles, such as the destruction of Sodom; they did not record earthquakes, because those came from nature and would always come back.1 source1 source

His second argument was against prophecy. God had forbidden men to meddle in what is to come, and nobody knows how an earthquake happens, let alone when or how big. Astrology was too deep to master, magic mere appearance, and the last prophet had been crucified. Then came his pun: pregar não há de ser praguejar, preaching is not meant to be cursing.1 source1 source

It worked, by his own account. The friars praised the speech, and “on the following Saturday all the preachers followed this view of mine”. Vicente presented it to the king as a service.1 source1 source

Readers have argued about what he meant. The scholar Andrée Crabbé Rocha saw a man who sensed a pogrom coming and staked the prestige of his name on a protest. Ana Carolina Ferreira and Manoel Santiago-Almeida are more cautious: Vicente defended scripture and the order of nature more than the New Christians themselves, and his plays mock Jewish characters. His solution, after all, was to convert them by kindness.1 source1 source

The earthquake did not create the Portuguese Inquisition; the king had been asking for one for years. In 1531 the pope did issue a bull granting it and naming the friar Diogo da Silva as inquisitor-general, but it was suspended the following year. The tribunal came five years later. On 23 May 1536 Pope Paul III signed the bull Cum ad nihil magis, and on 22 October it was proclaimed in Évora cathedral before the king and the court.3 sources3 sources

The tribunal sat first in Évora and moved to Lisbon in 1537; Évora and Coimbra had tribunals of their own from 1541. Between 1536 and 1605 these and the tribunal in Goa tried more than 10,000 people. Their main target was secret Judaism among the New Christians, the people the friars of Santarém had frightened into hiding. The Inquisition lasted until 1821; Lisboeta tells the story of one of its victims, António José da Silva, in a separate article.2 sources2 sources

When Lisbon fell again in 1755, people remembered 1531. In an official letter of April 1756, Sebastião José de Carvalho e Melo, the future Marquis of Pombal, called the new earthquake equal to the one Garcia de Resende described, except that this time fires followed, and he put the dead at 6,000 to 8,000. The two were different in kind: the 1755 earthquake came from offshore, south-west of Portugal, was much larger, with a recent estimate of Mw 7.7 and older ones of 8.5 or more, and brought an ocean tsunami and days of fire, a story told in a separate Lisboeta article.3 sources3 sources

The 1531 kind of earthquake is the one under Greater Lisbon's own feet. The Lower Tagus Valley has the highest seismic hazard in western Iberia, and Canora and colleagues framed their trench study in terms of the hazard to the Greater Lisbon area. Justo and Salwa wrote theirs partly with building design in the fast-growing estuary in mind.2 sources2 sources

The faults are quiet now compared with their history, with at least three moderate to large earthquakes in 1344, 1531 and 1909. At Alviela, Canora and colleagues roughly estimated one surface-rupturing quake every 350 years, but they note that faults inside plates often have clusters of earthquakes separated by long silences, not regular intervals.2 sources2 sources