The 1570 Ferrara earthquake struck the Italian city of Ferrara on November 16 and 17, 1570. After the initial shocks, a sequence of aftershocks continued for four years, with over 2,000 in the period from November 1570 to February 1571.
The same area was struck, centuries later, by another major earthquake of comparable intensity.
The disaster destroyed half the city, permanently marked many of the buildings left standing, and directly contributed to – but was not the sole cause of – a long-term decline of the city lasting until the 19th century.
The earthquake caused the first documented episode of soil liquefaction in the Po Valley, and one of the oldest occurrences of the event known outside of paleoseismology. It led to the establishment of an earthquake observatory which published to very high regard, and the drafting of some of the first-known building designs based on a scientific seismic-resistant approach.
Geology
The Po Plain, which is a foreland basin formed by the of the crust by the loading of the Apennine thrust sheets, overlies and mainly conceals the active front of the Northern Apennines fold and thrust belt, across which there is about 1 mm per year of active shortening at present. Information from hydrocarbon exploration demonstrates that the area is underlain by a series of active thrust faults and related folds, some of which have been detected from anomalous drainage patterns. These blind thrust faults are roughly west-northwest–east-southeast-trending, parallel to the mountain front, and dip shallowly towards the south-southwest. The 1570 earthquake has been linked to movement on the outermost and northernmost of these thrusts.
Ferrara
The city Ferrara is located on the Emilian side of the Po Valley, an alluvial plain geologically quite stable since the Messinian age (7-5 mya). Small earthquakes are common, albeit not frequent, but rarely lead to considerable damage to the urban cityscape. Ferrara was the location for minor earthquakes in the four centuries before 1570, these events being recorded in the city archives with detailed descriptions of damage to buildings and depositions by witnesses.
At the time of the 1570 event, it was a medium-sized city, with 32,000 inhabitants.
Despite continuous – and often victorious – wars against the age's superpowers, the nearby Venice and the Papal States, Ferrara in the 16th century was a thriving city, a major hub for trade, business and liberal arts. World class music and painting schools, linked with Flemish artistic communities, were established in the late 15th and early 16th century, under the patronage of the House of Este. Musical instrument workshops, and especially the making of lutes, were a pride of the city and were considered preeminent.
A new part of the city, named Addizione Erculea (Erculean Addition) had been built in the previous century: it is commonly considered one of the major examples of urban planning in the Renaissance, the biggest and most architecturally advanced town expansion project in Europe at the time.
Political, economical and religious situation
In 1570 the city was held by Alfonso II d'Este, Duke of Ferrara, vassal of Pope Pius V, a beloved ruler and a devoted liberal art patron, but careless and a big spender as an administrator. Alfonso was the main sponsor of many artists including Torquato Tasso, Giovanni Battista Guarini, Luzzasco Luzzaschi and Cesare Cremonini, confirming the reputation of Ferrara as a haven for artists and freethinkers. The emerging of the city as a cultural powerhouse came at the cost of a sharp increase in taxes.
The city was a safe refuge for Jews and converts from the persistent prosecutions promoted by the Roman Catholic Church. Despite Alfonso II's formal status as a vassal of the Holy Seat, he never took any action against the two thousand Jews living in the city walls, well knowing that the Hebrew community accounted for a strong share of the city cultural and economic success. His disregard of the Holy Seat's orders made him more than one enemy.
Even if he were walking on a thin line, Alfonso managed to avoid the Papacy's many diplomatic and legal challenges to the city independence, thanks to cunning politics and a strong friendship with the powerful Charles IX of France. It is to be remembered that Alfonso II was the son of Renée of France, member of the House of Valois, declared heretic and guilty of housing John Calvin himself under the eyes of the Catholics.
Alfonso was not new to compromises: to smooth his frequent brushes with the Pope, he was usually attending masses and acting as a good Catholic in public, receiving communion, giving substantial sums to charity, arranging religious parades for saints and building convents.
Both the high taxation, and the soft stance with the Jews ultimately gained him hostility in the most die-hard Catholic part of the population, which supported an acquisition of the city and its lands by the Holy Seat. Those rebel fringes were instrumental in the political struggle following the disaster.
The earthquake
Precursor events and main shock Earthquake lights were seen above the city on November 15, 1570, the night before the first quake. Flames were reported to come out from the soil and raise into the air, probably small pockets of natural gas set free by cracks in the earth crust. The earthquake struck at dawn: three strong shocks hit the city in the first day; one – the strongest – the day after. The first strong shock struck at 9.30 (local time) November 16, 1570, its epicenter just a few kilometers under the city centre. Six hundred pieces of stone masonry (mostly battlements, balconies and chimneys) are reported to have fallen, further damaging the flimsy stone and hay roofs. The following day the ground trembled again many times. At 8 pm a new powerful shock caused severe damage to walls and caused some buildings to sustain structural damage. Just four hours later, a new tremor caused new cracks and some collapse. At 3 am on November 17 the ground shook harder than ever; many buildings, damaged by the previous shocks, gave way and caved in. Many churches' facades, often built as self-standing walls rising well over the effective architecture, collapsed, including at the Duomo.
Forty percent of the city buildings were damaged, including almost every public building. Some of them collapsed, and many churches sustained critical damage to pillars and main walls. Observers reported that the shallow bowl-shaped valley where Ferrara lies seemed to rise into a kind of hump, before coming back to its original profile. Damage to the city were assessed in over 300,000 scudi, a huge sum at the time. The event was a surprise to many scholars, since according to the then mainstream theory of natural philosophy, earthquakes were not meant to strike in winter or on flat land.
Minor earthquakes had struck Ferrara in the past (events were recorded in 1222, 1504, 1511 and 1561, some of them causing little damage, and a stronger event in 1346). The exceptional length of the seismic swarm, unprecedented at the time in Ferrara, led some to believe it was a supernatural phenomenon.
The earthquake's intensity has been assessed as VIII on the Mercalli intensity scale: only the 1346 event was similar in intensity, though minor urbanization led to less evident damage (but more victims), the other have been all marked as class VII or VI. Other seismic events would hit the city in 1695, 1787 (three shocks in ten days) and 1796.
Initial damage evaluation
Palaces and public buildings Castello Estense, seat of the Duke, received major damage and became unfit for use. The Palazzo della Ragione (town hall) partially collapsed, as did the enclosure walls of both Loggia dei Banchieri and Loggia dei Callegari, in front of the Dome. Palazzo Vescovile (the Bishop's Palace) was destroyed, and had to be rebuilt. Minor damage was inflicted on the Cardinal Palace, Palazzo del Paradiso, Palazzo Tassoni and Duke Alfonso's personal palace.
Churches Damage to churches was widespread. San Paolo and S. Giovanni Battista churches collapsed, many paintings with them. Facades of S.Francesco, S.Andrea, Santa Maria in Vado, S.Domenico, and Santa Maria della Consolazione churches were severely damaged or destroyed, as was the Charterhouse's. The Santa Maria degli Angeli church, still under constructions, was so severely damaged that further work was abandoned. Other than the facade, the Duomo lost the Corpus Domini chapel and part of a side wing: the heavy iron chain above the main altar fell to the ground, along with the columns' fine marble capitals. San Paolo church had to be rebuilt from scratch.
Towers Many towers, a common kind of architecture in the Italian city skyline in the renaissance, were damaged. The Castle's bell tower collapsed to the ground, as did the top portion of the other three major towers of the town: Palazzo della Ragione's, the Porta S. Pietro donjon and Castel Tealdo tower. The Steeples of the Duomo, of S.Silvestro, S.Agostino, S.Giorgio and S.Bartolo churches were severely damaged.
Further shocks The seismic wave kept going for four years, but the worst was over after about six months.
Just one month after the earthquake, on December 15, 1570, a new powerful shock hit the city: this time the battered Palazzo Tassoni, S.Andrea church and S.Agostino church were not spared.
On the following January 12, 1571, a new shock damaged Palazzo Montecuccoli.
Victims Despite the widespread damage, fatalities were quite limited. The initial shocks alerted the population, and gave them time to evacuate the damaged buildings. The majority of houses were of one or two story height, and received less severe damage than the grander palaces and churches.
Reliable sources, such as historian Cesare Nubilonio, estimate 40 victims, while Azariah dei Rossi and Giovanni Battista Guarini both place the estimate at 70. Other sources vary from 9 dead to over 100, with some other occurrences of estimates of the order of two hundred or five hundred, usually taken as unreliable. Florence's ambassador Canigiani is known to have written home about 130 to 150 victims.
City evacuation
The poor and the wealthy People were scared by the disaster and about a third of the populace left the city for good. City jails collapsed and prisoners escaped the rubble, leading to a crime spree in the city and countryside.
The palaces of the notables and courtesans were damaged as well as the poorest mansions, and the whole city population had to seek shelter together in tents and refuges, despite their status or wealth. Contemporary account estimate eleven thousand people left the city.
The townspeople remained refugees for the following two years, due to the aftershocks. The resulting situation, in which societal rules were upset or fell in disuse, was perceived as awkward and unnatural by both peasants and well-to-do, leading to common psychological issues amongst the population. Along with the fear of aftershocks, people developed a sense of impending doom, precariousness and a general mistrust in humanity.
The country court Duke Alfonso II d'Este and his family barely escaped the collapse of a tower of Castello Estense. The lord fled the city by coach, and set up a temporary court in the fields of the San Benedetto garden near the city along with his closest advisor. This unusual improvisation was not well regarded by the Pope and was seen as demeaning by other rulers, but ultimately it proved to be a wise choice and a necessity in view of the duration of the aftershocks.
Ferrara's fate appeared sealed to the ambassadors visiting the refugee Duke: in correspondence between the embassies and the nobles, the region is sometimes called "di Val di Po dov'era Ferrara" (Po Valley, where Ferrara once stood). Florence's ambassadors were especially skeptical about the chances of city recovery.
Political struggle about the rebuilding