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The eruption of Vesuvius of 1631









(freely adapted and translated after Giacomelli and Scandone: "Campi Flegrei, Campania Felix"

INTRODUCTION

In Campania, besides the islands of Ischia and Procida, there are two areas of active volcanism with different peculiarities: Vesuvius and Campi Flegrei.

Vesuvius is a volcano with a conical shape, built by the accumulation of products erupted by a central vent during explosive and effusive eruptions. The proper vesuvian cone is built within an older volcano: Mt Somma, which constitutes most of the northern side of the volcano.

Campi Flegrei do not have any central conduit and the eruptions gave rise to cones of smaller dimensions scattered oved a wide area. The distribution of the vents follows the trend of the fractures formed during the collapse of the area after violent explosive eruptions. This depressed structure is called "caldera".

The city of Napoli is embedded between the two active volcanoes Vesuvius and Campi Flegrei which had an important influence on its life.

The campanian area is also affected by moderate tectonic earthquakes that originate on the nearby Appennines mountains. In the first half of 1600, all the kingdom of Naples was hit by catastrophes: on 1627 a violent earthquake shakes the Apulia area (to the east) and destroys the city of S. Severo causing 5000 deaths; on 1631, Vesuvius comes back into activity with the major eruption of the last 1000 years and again in 1638 one of the largest, ever occurred earthquake of southern Italy, occurs in Calabria destroying the territories of Cosenza.

During this period southern Italy is below the domination of the spanish empire which imposed heavy taxes. The vice-king of Naples the Duke of Medina, collected during the six years since1636, 44 milions ducats and caused a violent insurrection of the neapolitan people in 1647. The insurrection was named after its most popular chief Masaniello.

The tragedy of Naples reached its apex in1656 with the plague which halved the population of the town to 200000 inhabitants.

Volcanic activity had recently occurred only in Campi Flegrei, where in 1538, a new volcano named "Monte Nuovo" formed in only a few days. Vesuvius had long since been inactive and people used to call it the mountain of Somma. The volcano, inactive since long time (probably since 1139) and covered with a thick vegetation, come back to life in 1631 with one of its violent eruptions.


CRONICLE OF THE ERUPTION

The description of this eruption is made using the words of two witnesses of it: Giulio Cesare Recupito (De Vesuviano Incendio Nuntius) and Giulio Cesare Braccini (Dell'Incendio fattosi al Vesuvio a' XVI Dicembre 1631, e delle sue cause ed effetti).

Recupito is translated from latin and we leave in the original language only a few sentences that point out to the main facts of the eruption. The texts have been freely translated and abridged to avoid the arcaism of the 1600 language.

------------------------------------------------------------------------------------------------------------------------Primus terror, terremotus

--------------------------------------------------------------------------------

A FEW WEEKS BEFORE:

Braccini

The inhabitants of Torre and Massa, Polena and S.Bastiano state that since the 10th of December they heard the mountain roaring from the inside, with such a stirring of subterranean spirits that they could hardly sleep at all during the night. Others say that the water in some wells became dirty without any rain and other wells became dry. Moreover, as a trustworthy Ottaviano citizen relates, that having climbed the mountain a month earlier up to the crater rim, he descended to the crater's bottom; on having returned to the same place fifteen days later, he found that the ground had now risen in such a way as to make it possible to cross over from one side of the rim to the other without stepping down for any length.

THE NIGHT BETWEEN 15 AND 16 DECEMBER:

Recupito

Earthquakes, particularly strong occurred during that night when we thought the same city teared from its foundations.

For two days there were continuous tremors and frequent quakes: in the following five days the earthquake became less frequent until the all tragedy ended. In Naples, no house fell down but many were damaged. At Herculaneum, the palace of the Archbishop partially collapsed.

Monday,15 december

Around 5 o'clock in the night (the hours were counted starting from 7 pm; with the current use it was midnight) one servant of the Marquis d'Arena states that he saw, from the Maddalena bridge a bar of fire that rose from Pozzuoli and stretched all the way into Vesuvius. And inhabitants of Resina (Ercolano) relates that they saw the same phenomenon for many days before. In that same time I felt a small earthquake, but, in the places near to the mountain since that hour (midnight) till 12 of the morning (7 of the morning), they counted in some place 18, in another place 50, one largest that the other.

Tuesday 16 december

A little later (after 7 in the morning) The mountain opened in the Atrio (between the southern part of Monte Somma, where is now the Salvatore hill, and Gran Cono). In a short time everybody saw flames and smoke and ash and stones coming out from different openings; and a certain Santolo di Simone who was as near as half a mile from the vent, on that same morning saw, in that plain, smoke and fire coming out from different fractures, that, on opening produced a sound like that of firecrackers on a holiday; and these vents were, in the beginning as wide as a wine tub and became wider and wider; then the smoke emission became a cloud with lightnings and stones. Other relate to have seen different fractures emitting stones and bitumen matter behind the great crater.

------------------------------------------------------------------------------------------------------------------------Secundus terror, pluia cinerum

------------------------------------------------------------------------------------------------------------------------

After the sunrise, a dense and extraordinary cloud was observed on the mountain from Naples which appeared as an high and wide pine-tree (mediterranean pine)

But the sun still shone here (Naples) with its warm rays;. when at 18 hours (1 pm) the vapors became so strong that the air became black and obscure and we smelled sulphur and burnt bitumen; so fetid it was that I was impeded the breathing.

At 21 hours (4 pm), we started feeling in Naples a continous tremor that houses were shaking and roofs were falling. For three hours there was such a strong noise, and a continous shattering of houses, and horrible flashes.

That cloud came up from Vesuvius like a mountain in between fires. At a first time it was driven toward Naples by the wind then became ash laden. The next morning, at daybreak, everything was covered by ash. That same day, that the mountain burnt for the first time, ash rained in many cities of the kingdom of Naples.

Ash fell in Benevento, Bari and Taranto; driven by the wind it reached Dalmatia and even the sea. The ash, fallen by the cloud reached the Aegean and made white the sea. We heard that the ash reached the southern lands of Lucania and Stilo and, even Africa.

-----------------------------------------------------------------------------------------------------------------------Tertium terror fuit, pluia lapidum

-----------------------------------------------------------------------------------------------------------------------

(In the areas Est of the volcano) At 14 hours (9 am) the smoke was so dense that looked like night when actually was the day. (The princess of Ottaviano started moving toward Cacciabella) sent a slave to Ottaiano to see what had happened there. On his way, the slave saw the falling of rocks as big as ten or fifteen "ruotola"; and came back shouting:"escape escape...". Around 16 hours(11 am), also in Cacciabella started the fall of the same stones, so even the Signora Principessa was forced to leave even if the sky became a little more clear and she was always accompanied by that fall of stones, that fell all the day long, and since 24 hours (7 pm) till 4 in the night (11 pm) there was an heavy lapilli rain and then sands until day, and then rain until 16 hours(11 am) of the following wednesday .

Stones fell from the sky not only in Nola and in the towns near to Naples, but also in the Melfi environment in Puglia which is 100000 paces from Vesuvius. And they were not only pumices but also stone so big that they found one that could not be moved by ten pairs of oxen. You could say that they were not falling stones, but boulders.

The stones falling toward this direction (S. Gennaro) were of different quality, color and bigness. One fell over the cellar of the Marquis of Lauro as far as 12 mile from the mountain. The ash and sands rained in such an amount that the road to Puglia until Ariano was raised twelve palms, one in Lucera, in Foggia a little less, in Barletta, in Bari, in Lecce and in Otranto, one inch; even if in Modogno, near Bari someone wrote to have collected as much as 24 "tumula"; and everywhere it began before 22 hours (5 pm). In Naples this did not occurred before 23 hours (6 pm) and very little, because was not as much as an inch.

-----------------------------------------------------------------------------------------------------------------------Quarta lues, ac terror, torrens igneus

-----------------------------------------------------------------------------------------------------------------------

Wednesday 17 december

At 8 hours (3 am) having doubled the uproar of the mountain, liquid matter began to be emitted from the chasm into the Atrio even if there was no rain over the earth until 16 hours (11 pm) of the next day.

At 14 hours (9 pm), the earthquakes became stronger and stones started again to fall in the plain of Nola with sand and lapilli stones. And it was so dark, that people could not see each other even with burning torches.

With a growing thunder, a fire stream came out from the top of the mountain, and with sulphur, bitumen and ash came down from the flank to the plain with vehemence and crash. This torrent, before reaching the fields, divided itself into different streams like a river.

We felt a very large earthquake(about 11 am), and there was such a large and fast stream, firstly toward Ottaviano, then it divided into three deep channels gushing into the plain of Nola, and sank S. Elmo, Saviano, and all that land, drowning many people and raising in some place the land as much as 12 and14 palms, like in Marigliano, Cicciano, and Cisterna. Another stream engulfed S. Maria della Vetrara, and ruined all Massa, and what was left of Trocchia, half of Pollena, and major damages in S. Sebastiano. Later on, the same streams flowed toward the marina, and divided into three channels, one toward Bosco, the other between Torre della Annuntiata, and Torre del Greco, and the third and smaller over Resina; a little later there was another toward Somma. These streams caused the major damages.

And they were so fast that, besides being very large, they were getting bigger by transporting everything they found on their path.

Also the sea retired for a large space for about a mile, and so remained one eight of an hour, and the retirement was so fast that the ships were left dry on the sand. At the same time the top of the mountain was wide open and had a circumference of three miles and it was much lowered, and everyone thought that it had lost one third of the height that it had the day before.

-----------------------------------------------------------------------------------------------------------------------Quintus et postremus terror, acquarum inondatio

-----------------------------------------------------------------------------------------------------------------------

Who could believe that Vesuvio which is in front of the sea could emit a stream of fire and a stream of water. So while it was emitting flames from the crater, on the other side toward the fields of Palma andNola, it began to pour such a large quantity of water with an incredible strength.

A little later, we saw during a period of good weather the same streams becoming also larger than the previous. Toward the marina they destroyed completely Bosco, Torre della Nunziata, Torre del Greco, Granatello and part of Resina and continued to flow until 19 hours (2 pm), and they were seen also from Napoli like very high and wide rivers.

The water submerged everything transforming the fields into water fields and in the beginning it raised to an height of 15 palms and lately decreased. The waters with the same momentum of the fires were flowing from the mountain and transporting trees, villages, houses, rocks and they runied not only the poor buildings but also palaces, reaching the height of the roofs and in the cellars destroying barrels of precious wine.

The rain of ash lasted in Naples until 17 hours (midday), when having changed the weather it began the fall of such a rain from the sky that there were rivers in the roads and it lasted all day long.

Thursday 18 December 1631

Around 17 hours (midday)the same clouds were seen on the mountain as those seen on tuesday and perhaps higher up to 35 miles, but at that height they were white and dispersed in the air. In the clear air we could see the rivers of water flowing toward the marina. At the same time an horseman near the Palace of the Prince of Caserta at Barra was reached and killed by a river of hot ashes and stones. 


END OF THE ERUPTION

Friday 19 December

The cardinal sent priest to the ruined lands, having known that they could be reached without danger.

Saturday 20 December

As for the fire there was no bad news. In Naples we heard nothing more than an extraordinary rumble on the 29th. Some sailor saw on Vesuvius a large fire like a fire thrust falling onto Marano, and in the sea.


CONSIDERATIONS ONTO THE ERUPTION

We used the already cited contemporary accounts of Braccini and Recupito, G. Battista Masculo (De incendio Vesuvii), and also those of G. Bernardino Giuliani (Trattato del Monte Vesuvio e de suoi incendi) and a letter of G. Battista Manso, Marchese di Villa.

Besides the numerous contemporary accounts of the eruption there is still a disagreement among volcanologists about the true occurences of lava flows during the eruption of 1631. Most of the accounts were made by terrified people who lacked real experience of such volcanic phenomena, because the volcano had been quiescent since long time. The scholars that observed the eruption felt the importance of the moment but it is always difficult to test the accuracy of their descriptions according to modern standards.

Another difficulty is that of reconstructing the temporal succession of the events because hours at that time were counted starting in the evening. G. Battista Masculo tells that the 17th hour in Napoli was midday and permit us to compare the hour citation with the present method of counting the hours.

The major disagreement among volcanologists deals with the true occurrence of lava flow during the eruption. According to someone: citation " rivers of liquefied boiling sulphur, bitumen and ash" (Giuliani) or "sulphureous water, bitumen such on fire like liquified lead or thin" (Braccini) could have been used to describe the lava flows. According to others these words refer only to pyroclastic flows.

It must be recalled that the term lava which we presently use to definy a flow of molten rocks, origins from the neapolitan dialect and was originally used the identify the flows of water and mud that were observed along the flank of the hill of Naples after strong rainstorms. It has its origin from the latin Lavare (to clean). The modern use of the word started around 1737 when it was used by Serao (1738) "flow of flaming lava" to describe an actual lava flow during an eruption of Vesuvius.

1 - PRECURSORY PHENOMENA

The awakening of the volcano was signalled some days before by the occurrence of several earthquakes felt in the villages around Vesuvius. There is no evidence that these earthquakes were felt in Naples so they must have been of moderate magnitude and very near the surface.

15 days before the eruption the water wells became muddy and in some case there was a decrease of the height of the water table. At the same time it seems that there was an uplift of the bottom of the crater. Such phenomena were observed also before other eruptions of Vesuvius

In the night between 15 and 16 December, the earthquakes become more intense and they are felt also in Naples

2 - BEGINNING OF THE ERUPTION

Around midnight of 15, in Naples were observed flashes onto the mountain. The Marquis Manso, from Naples observes a big fire rising partly toward the sky and partly flowing along the flank of the mountain.This is the beginning of the eruption from the central vent. It is possibly characterized by a moderate explosive activity with eventually a lava flow toward Portici.

The inhabitants of the vesuvian villages were frightened. The bishop of Naples, being in Torre del Greco, rapidly fled from the town with a boat. On the following morning he orders a procession, that leaving from the Cathedral must reach the church of "Il Carmine" bringing the relics of Saint Januarius, Patron of Naples.

3 - PLINIAN SUSTAINED COLUMN

On the morning of 16th, the eruption increase its violence. Along the cleared conduit the magma rises and exsolve the volcanic gases; an high column of gas pumices and ashes rises into the sky to an height of 30 miles. The column widen at the top and has the form of a cauliflower, transported by the stratospheric winds toward the north-east. The products fall from the column and ashe and pumices cover a large area to the north-east of the volcano.

Around 1 pm of the16th, even Naples is reached by the ashes that make difficult the breathing.

At 3 pm begin the procession ordered by the bishop and a little later, in the town starts to be felt a continuous shaking of the ground which increase in intensity and cause the panic of the population.

At 6 pm the procession reaches the Carmine church accompanied by a strong shaking of the ground and the fall of ash. The fear was such that also the prostitute promised to give up their habits.

4 - PULSANTING COLUMN

A plinian column can be sustained as long as it remains lighter than the surrounding atmosphere. The column collapses when there is too much material erupted and not enough air to mix with it, so the material is denser than the air and flows along the flank of the volcano as pyroclastic flows. Many explosive eruptions pass from a sustained column to a collapsing column in only a few hours.

During the night of 16th, the inhabitants of Naples see a fire ontop the mountain and a fall of ashes mixed with water in the town. At this time there is a report of a lava flow along the western flank of the volcano.

The dense fall of ash and waters lasts until midday of 17 and no clear view of the volcano is possible. At this time a violent storm clears the air.

5 - PYROCLASTIC FLOWS

A strong earthquake occurs around 11 am of 17, and the eruption reaches its climax. The quake causes a retreat of the coastal line. The sea comes back after ten minutes with a wave high 4 to 5 m. At least five pyroclastic flows come out from the top of the volcano and rapidly reach the sea. (Giuliani). There is a collapse of the crater which becomes lower than the nearby rim of the Somma.

6 - MUDFLOWS

The pyroclastic flows are followed by mudflows that continue to flow until 2 pm of 17. The mudflows hit especially the northern area of the volcano between Palma and Nola.

The decline of the eruption starts after the 2-3 pm of 17 and during the late afternoon there is again a sustained eruption column with little ash.

Landslide of volcanic material occur during the 17 and the following days along with floods favoured by the scarce permeability of the newly erupted materials.

At the end of the eruption the cone of Vesuvius is lowered of a third of its original height. 


DAMAGES AND CONSEQUENCES OF THE ERUPTION

"Better would have been to cancel the memory of the calamities brought us by the fire of Vesuvius, with tears of desperation and buried in perpetual silence than to repeat it to our descendants".

 

 
 
 

These words of the Abbey G.Braccini provide a good idea of what damages had been made by the eruption

"Densely inhabited lands, wonderful villas, with rich and sumptuous gardens, and many large Palaces with lovely orchards and gardens" were all destroyed by the fury of Vesuvius."

 

 
 
 

During the month of February the abbey Braccini goes to Vesuvius passing through

"lands damaged, part from the fire, part from the ash, some from the fallen stones and much more from the water"

 

 
 
 

Three miles outside Naples, toward Ottaviano, all the country is covered by ash, and there is no grass. The lands and country houses of S.Giorgio a Cremano, S. Sebastiano, Massa, Pollena and Trocchia are destroyed. 200 buildings of Sant' Anastasia have collapsed because of the ash, and many more are those damaged in Somma. Everything around Vesuvius is destroyed by the pyroclastic flows. Bosco is completely destroyed, in Torre Annunziata there are only fourteen houses standing. All the fields are covered by ash; around Ercolano the ash is 15 palms thick. in Torre del Greco the only buildings undamaged are those of the Princess Palace, the Church of S.Maria della Grazia, the Convent of Padri riformati, the house of the Bishop and the Church of Incurabili.

"They estimate, that only the damage of the buildings and churchs exceed the value of 2 millions ducats. Taking into account also the burnt territory I can estimate a total damage of 25 millions ducats" (Braccini)

 

 
 
 

Other damages occurred also in territories far from the volcano within the fall out area of the ashes and punices. So in the area of Avellino there were many damages and the populations were relieved by the payment of taxes for several years (Francesco Scandone, 1950)


BIBLIOGRAPHY

Last modified 28-10-97
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