The chronicle of 1669 Mt. Etna eruption
Numerous historians agree in identifying in this eruptive event the moment of breaking the balance between the city of Catania and its rural territory. From a volcanological point of view, the eruption of 1669 is considered an extreme event, such as to radically change the volcano's behavior and eruptive style in the following centuries. This eruption closed an eruptive period characterized by numerous lateral eruptions during the late Middle Ages, which also occurred at low altitudes (below 1000 m above sea level). After the eruption of 1669 and up to 1727, there was a period of very low eruptive activity, followed by a gradual increase in activity, both at the top and at the side, which largely affected the medium-high altitudes of Etna, unlike the previous centuries.
Mount Etna eruption of 1669 was preceded by intense seismicity, which began at the end of February and which reached its peak between 10 and 11 March with the destruction of the town of Nicolosi. At about 4:30 pm on 11 March, a series of eruptive fissures opened, oriented NNW-SSE, which developed from about 950 m up to 700 m on the southern slope. The main eruptive vent was formed east of Mt. Salazar's cone, between an altitude of 775 m and 850 m; here, an intense explosive activity gradually increased in the following months, forming an imposing cinder cone. During the first month of the eruption, the intense explosive activity at the mouth of Monte Della Ruina generated an eruptive column which, falling back to the ground, produced a pyroclastic deposit of lapilli so thick and heavy that it caused the roofs of numerous houses in the towns of Pedara, Trecastagni, and Viagrande to collapse. The fall of the finest pyroclastic products (ash) affected a large area, reaching Calabria and south-eastern Sicily. Overall, the total volume of erupted pyroclastic products, both proximal - precisely the cone of Monte Della Ruina - and distal, was approximately 66 million cubic meters.
The eruption lasted four months: in this period, about 600 million m3 of lava were erupted, with an average effusive rate at the mouth of 58 cubic meters per second, which are among the highest values recorded in the last 400 years. A huge lava field of 40 km2 (430.556 sq. ft.) formed, while a 17 km long lava stream was produced, the longest lava flow on Mount Etna's geological record of the last 15,000 years. In the initial phase, the lava flow split into two streams, east and west, due to the morphological obstacle posed by Mt. Pilieri scoria cones. On March 12, the lava destroyed Levuli and Guardia's villages and the town of Malopasso, advancing with a front about 2 km. wide. During the night of the same day, the lava flow covered the Annunziata church, which was about 2 km from the main mouth. It destroyed the village of Mompilieri. On March 14, thanks to an effusive rate of 630 m3 /s, the western lava stream reached San Pietro and Camporotondo. Between 15 and 17 March, a new lava stream headed south-east. The eastern arm reached the town of San Giovanni Galermo, partially destroying it. After two weeks of eruption, the effusive rate had decreased to 170 m3 /s. The eastern stream stopped definitively after touching Torre del Grifo's locality, north of Mascalucia, and having damaged the cultivated lands of Gravina, reaching a length of 8, 8 km. Meanwhile, the western stream had reached its maximum length of 10 km, expanding into the Valcorrente quagmire, bordering the hills' sedimentary soils called Terreforti. Simultaneously, the arm that flowed to the south-east was divided into several flows that advanced in the locality of Carcarazza, located about one-kilometer north-west of the town of Misterbianco. During these two weeks, lava tunnels began to form in the west and south-east arms. Between 26 and 29 March, new lava flows were generated from the western arm, which destroyed San Pietro and Camporotondo. The most advanced front continued to invade the Valcorrente quagmire. In the same days, the south-eastern arm began to destroy some houses in the town of Misterbianco, which was completely buried on April 30
About a month after the eruption began, although the effusion rate had slightly decreased (30 m3 / s), the south-eastern arm continued to advance thanks to the development of new lava tunnels. In mid-April, the lava had reached and covered a small swamp called Gurna di Nicito and threatened the western portion of the medieval walls of Catania. On April 16, the lava flow leaned, for the first time, on the section of the defensive curtain between the bastions of the Infected and the Tindaro. The city's fortifications were propped up, the access gates walled up with large blocks of lava stone; the lava flows were contained by diverting them towards the coast, where important architectural structures of the Roman era, the Circus Maximus and the Naumachia, were buried. The lava flow diverted from the walls reached the sea for the first time on April 23. In this period, Prince Don Stefano Riggio di Campofranco was appointed vicar general "for the fire of Mongibello" by the viceroy of the Kingdom of Sicily. The Duke of Albuquerque, Stefano Riggio, identified an evacuation site in the locality of Ognina where a camp was built to house the bishop, the senators, and the citizens. The relics and sacred furnishings of churches, artillery, and food supplies were also transported to the Ognina camp-site.
April 30 was a crucial day for the Catania's dwellers under the lava flow pressure; a 57-meter long wall collapsed between the bastion of the Infected and the Tindaro. That tragic day the flow entered the city, slowly advancing towards the monastery of San Nicolò l'Arena, which was reached by the lava between 1 and 5 May, and also entering the south-east sector of Catania. In those dramatic first days of May, with the lava advancing insideCatania, the city senate met to discuss the possible abandonment of Catania and the consequent relocation of the town to a new site and, again in those days, there was the unsuccessful attempt to divert the lava flow near the Malopasso area, by a group of men from Pedara, led by the governor and priest of the town Don Diego Pappalardo. This pioneering attempt to deviate the lava stream was achieved by breaking an embankment of the lava flow channel. The cost of the operation was financed by the vicar general Stefano Riggio and the Catania senate. Both the vicar general and the Catania senate also organized interventions to contain the city's lava flow, constructing dry stone barriers. On May 8, the casting stopped after destroying numerous houses, some noble palaces, and several churches.
Meanwhile, other lava flows continued to accumulate along with the southern sector of the defensive curtain known as "under the Castle." In this area, on May 16, the lava flow went beyond the walls. It began to pour into the Ursino castle's moat. On June 9, the casting almost reached the windows' height, which were bricked up, and the castle was abandoned. In the following days, the destruction of a part of the city's southern sector was completed. During May and June, the main lava flow, fed by the lava tunnels, continued to pour into the sea, where it will form a total lava delta about 1,500 meters wide, causing the shoreline to move forward by about 800 meters.
The period between May and June 1669 represents, best of all, what has been identified as the moment of breaking the balance between the city and the surrounding area. According to the historian Giuseppe Giarrizzo, Catania before 1669 could be defined as a "white city" thanks to the richness of the surface waters of the Amenano: this, incorrectly called "river," was a small drainage network fed by different sources of the outcrop of clayey soils and, precisely in the southern sector of the city, the lava flow buried the so-called "36 Canals", a source in which the waters of the Amenano had been conveyed for public use in 36 pipelines. Thus Catania suddenly and definitively lost its characteristic of "white city"; the surface waters disappeared, and the city turned into a "black city," dominated by lava. Nevertheless, the eruption effect was not limited only to the change in the hydrographic network. It also radically changed the surrounding landscape, isolating Catania from the Simeto river plain's fertile soils. Above all, it changed what for centuries had been the defensive role of the city's predominant architectural element, the Frederick fortress of the Ursino Castle, forever nullifying its relationship with the sea.
The eruption ended on 11 July 1669, after four months of intense activity both explosive and effusive, rewriting the history of the territory of the city of Catania and representing an extreme event in the eruptive history of Etna as regards the volcanological aspects, the impact on the population and the urban fabric. At the end of the 1669 eruption, the damage was done but not that of the dead; in fact, it is important to remember that the most destructive lateral eruption of historical times did not cause any death among the population, on the contrary, it constituted a strong impetus for the rebirth of the city and the surrounding area. The response to the volcanic emergency by the local authorities and the population was immediate. The Spanish monarchy's request for new infrastructures would have endowed the city with greater political and economic competitiveness. Suffice it to say that at the end of September, less than three months after the end of the eruption, the viceroy granted the license to construct a new village.
It is striking that the inhabitants of Catania, who survived the great eruption of 1669, twenty-four years later, will face another massive catastrophic event, the earthquake that struck south-eastern Sicily on 11 January 1693. On that day, 63% of the approximately 20000 dwellers of Catania died under the collapse of that city, which 24 years earlier had been saved from the lava flow. Catania was completely rebuilt in the place of foundation to preserve the thousand-year-old memory of its history. This choice has been and will forever be the figure of this city's destiny and population.
Remembering the dramatic event linked to the eruption of 1669 not only from a strictly volcanological point of view, after 350 years, is a necessary and fundamental exercise of our collective memory, useful for countering the oblivion of natural phenomena that violently impact a territory. What have we learned from events like that of 1669 or more recently from that of 1928 that destroyed the town of Mascali? What has been the awareness and knowledge about the natural risks of the Etna area over time? The answer is simple and is linked to the recent history of uncontrolled urban expansion that began in the second half of the twentieth century, built without respecting the memory of one of the most active volcanoes in the world.