Overblog
Editer l'article Suivre ce blog Administration + Créer mon blog

Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié le par Bernard Duyck
Publié dans : #Eruptions historiques, #Des volcans et des hommes.

A vigorous seismicity preceded the onset of eruptive activity by more than two months, and the earthquakes became particularly intense on March 8, 1669. The last earthquake seems to have been accompanied by the opening of a 9 km fracture. extended from Monte Frumento Supino (slag cone located about 2 km south of the summit, at 2845 m altitude) to Monte San Leo (at 1200 m altitude).

Reproduction of a fresco in the cathedral of Catania, showing the eruption of Etna in 1669 whose lava flow has caused extensive damage in Catania and destroyed many villages. - one click to enlarge - This drawing shows the main crater of the eruption near Nicolosi in vigorous explosive eruption and the lava flows extending from it (in red color) to Catania. In the lower left, the Castello Ursino is surrounded by lava. North of the city, one can also see the lava flow still eroded a few centuries earlier (perhaps in 1381) from a crack near the village of Mascalucia, which entered the sea in Ognina, today a densely populated part of Catania.

Reproduction of a fresco in the cathedral of Catania, showing the eruption of Etna in 1669 whose lava flow has caused extensive damage in Catania and destroyed many villages. - one click to enlarge - This drawing shows the main crater of the eruption near Nicolosi in vigorous explosive eruption and the lava flows extending from it (in red color) to Catania. In the lower left, the Castello Ursino is surrounded by lava. North of the city, one can also see the lava flow still eroded a few centuries earlier (perhaps in 1381) from a crack near the village of Mascalucia, which entered the sea in Ognina, today a densely populated part of Catania.

On the afternoon of March 11, probably around 4 pm, several vents opened in the area between Monte Nocilla and Monte Fusara, immediately northwest of the condemned Nicolosi village. These vents produce incessant and powerful explosions, while a huge lava flow emanates from vents further downstream. Over the next few days, explosive activity, which continues strongly in the main vents, began to build a large pyroclastic cone, which was originally called "Monte della Rovina" (mountain of destruction) but is now known as Monti Rossi. Meanwhile, the lava flows into two main branches. The remains of Nicolosi and the villages of Mompilieri and Malpasso were consumed during the first 24 hours of the eruption. Over the next three days, the villages of San Pietro Clarenza, Mascalucia, Camporotondo and San Giovanni Galermo disappeared under the huge river of lava, which is advancing rapidly and relentlessly towards the south, heading towards the city of Catania.

Map of the flows on the SSE side of Etna in 1331 (?) And 1669 - map in www.italysvolcanoes.com/ ETNA1669.- Doc Boris Behncke

Map of the flows on the SSE side of Etna in 1331 (?) And 1669 - map in www.italysvolcanoes.com/ ETNA1669.- Doc Boris Behncke

One week after the beginning of theeruption, the two main lava branches are heading towards the main towns of Paternò and Misterbianco, burying a number of small villages on their paths, which have never been rebuilt and whose are not known. The easternmost stream devoured Misterbianco on March 25 before settling in a small depression west of Catania (the "Gurna di Nicito"), which was probably filled with a lake. Once the depression filled, the lava resumes its lead towards Catania.

Lago di Nicito and Bastione degli Infetti, before the eruption of 1669. - go Etna

Lago di Nicito and Bastione degli Infetti, before the eruption of 1669. - go Etna

The day that Misterbianco was destroyed (March 25), violent explosions occurred at the top of the crater, announcing the partial collapse of the summit of the cone. The explosions accompanying the collapse were probably phreatomagmatic and blocks up to 15 m in diameter were ejected at a distance of 1 km from the crater, while hot slag falls occurred up to 8 km from the summit (Tanguy and Patanè, 1996) .The eastern lava flow reached the walls of the city of Catania on the west side of the city in early April and was deflected southward by the walls, which initially withstood the pressure of the river of molten rock. On April 23, the lava, which had previously encircled the Castello Ursino (a Norman fortress located on the south shore of Catania), entered the sea with a front more than 1 km wide and quickly filled the port of the city. At about the same time, the level of lava accumulated against the walls of the city in western Catania gradually increased to the crest of the structure. This slight overflow of lava caused little damage, but the worst was yet to come. On April 30, part of the walls gave way under the pressure of the lava, allowing it to enter the city from the west. Two lava lobes surround and partially destroy churches, monasteries and other buildings around the church of San Nicolò l'Arèna. Walls were hurriedly built along the main roads leading to the lower areas of the city to stop the advance of the lava in the city. On the basis of contemporary documents, Pagnano (1992) describes these walls as very functional and managing to prevent the lava from causing more extensive damage. However, during the month of June, more lava flows reached the area of ​​Castello Ursino and the coastline, raising fears of another destructive invasion of Catania by lava. It seems, however, that the worst was over, even though the eruption continued for a month before ending on July 11th.

Etna eruption of 1669 - Progression of lava flows between March 11 and July 11 - doc in Impacts of the 1669 eruption and the 1693 earthquakes on the Etna Region / S.Branca

Etna eruption of 1669 - Progression of lava flows between March 11 and July 11 - doc in Impacts of the 1669 eruption and the 1693 earthquakes on the Etna Region / S.Branca

Etna and Catania during the eruption of 1669. - Borelli, Giovani Alfonso (1608-1679). Historia, and meteorologia incendii Aetnaei anni 1669. Reggio di Calabria: Domenico Ferro, 1670.

Etna and Catania during the eruption of 1669. - Borelli, Giovani Alfonso (1608-1679). Historia, and meteorologia incendii Aetnaei anni 1669. Reggio di Calabria: Domenico Ferro, 1670.

The devastation caused by the eruption of 1669 was very wide. At least 10 villages have been completely destroyed and many more severely damaged by lava flows and, to a lesser extent, by tephra falls. The western part of Catania suffered heavy damage due to the invasion of lava. The areas to the west and southwest of the city, once rich in fruit gardens and various villas and several monuments of Greek and Roman times, were turned into wasteland and Catania was now surrounded by lava flows of all sides except on the sea.

From Catania, only a relatively small part was destroyed. Shortly after the invasion of Catania by the lava, steps were taken by the vicar Don Stefano Reggio to protect the lower areas of the city: the construction of stone barriers in the main streets. "The speed of decisions, the smooth operation and the efficiency of the operation must be admired, given the tools available at that time, and the dimensions of the problem, which would represent enormous difficulties even in a modern state if confronted to a situation "(Pagnano, 1992).

The houses next to the lava front were demolished to use the bricks for the construction of a great barrier across the Strada del Corso, the most critical place. The lava flow was indeed stopped by this obstacle, and another similar barrier was built near the church of Madonna della Palma, where another flow had pierced the walls of the city.

Portrait of Don Pappalardo

The success of these efforts led to another, more famous, attempt to divert the lava flow much closer to its source, in order to stop the supply of active lava fronts in the Catania region. This attempt, led by a group of people led by Don Diego Pappalardo de Pedara, commander of the Order of Malta, aimed to break the roof of the lava tunnel (or the lateral dyke of the main flow channel). In this way, the lava should be forced to cool rapidly outside the tunnel or protection channel. It is often mentioned that after the success of their efforts, armed men from Paternò arrived at the scene, because the new artificial flow threatened their city, and forced Pappalardo and his men to abandon the hijacking site. As a result, the lava flow would have reoccupied the old tube system (or flow channel), and the lava flowed back to Catania.

In any case, the series of protective measures implemented in Catania and near the eruptive mouths seems to have been largely successful. Because of the often cited differences between the inhabitants of Paternò and those of Catania during the last diversion effort, any diversion of artificial lava flow was prohibited by law in Italy until 1983.

Sources:

- Italy's volcanoes - The cradle of volcanology - by Boros Behncke

- Impacts of the 1669 eruption and the 1693 earthquakes on the Etna Region (Eastern Sicily, Italy): An example of recovery and response of a small area to extreme events - S.Branca & al.

Commenter cet article

Articles récents

Hébergé par Overblog