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Death, Survival and Damage during the 79 AD Eruption of Vesuvius which destroyed Pompeii and Herculaneum

December 2019

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Authors:

Roberto Scandone

National Institute of Geophysics and Volcanology

Mauro Rosi

University of Pisa

The eruption of Vesuvius of 79 AD is the first large explosive eruption described in detail by Pliny the Younger. The eruption began with a high eruptive column depositing a thick airfall pumice deposit to the South East of the volcano, and it was followed by the emplacement of destructive glowing avalanches which destroyed the cities of Pompeii, Herculaneum and Stabiae. In this paper we re-evaluate the succession of the events based on the letters of Pliny, the volcanic deposit and the extensive damages caused also by the earthquakes occurring during the eruption. We estimate the impact of the synchronous seismic activity by evaluating its intensity and effects on the wider Campanian plain and drawing novel isoseismal maps. We suggest that the strong intra-eruption seismicity conditioned the behavior of the inhabitants of Pompeii during the eruption, compelling many of those, that were still in the houses to flee from the collapsing buildings. We suggest also a different timing of the travel of Pliny the Elder from that proposed by earlier authors We infer an earlier destruction of Herculaneum during the first day of the eruption, as witnessed by the Elder during his travel from Misenum to the vesuvian region, which compelled him to deviate to Stabiae where he died, the following day, a few minutes after the inhabitants of Pompeii.

Archeological findings at Villa Regina (Boscoreale) that suggest an Autumn date for the eruption. a) Sealed jars containing grape must, b) pomegranate, c) hazelnut, d) figs. Photo: Giacomelli and Scandone.

…

The Port of Misenum and, in the background, the internal lagoon, base of the fleet (Classis Praetoria Misenensis Pia Vindex,) commanded by Pliny the Elder. Photo: Giacomelli and Scandone.

…

Stratigraphy of the products of the eruption by Cioni et al., 1992.

…

Eruption deposits at Pompeii outside Porta Nolana, resting directly on the Roman road. Photo: Giacomelli and Scandone.

…

Deposits of the early pyroclastic density currents at Herculaneum in the tunnel in the wall facing the excavations. They were responsible for the deaths inside the arcades. Photo Giacomelli and Scandone.

…

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J-READING

JOURNAL OF RESEARCH AND DIDACTICS IN GEOGRAPHY

2, 8, December, 2019, pp. DOI:

Death, Survival and Damage during the 79 AD Eruption of

Vesuvius which destroyed Pompeii and Herculaneum

Roberto Scandonea, Lisetta Giacomellib, Mauro Rosic

a INGV – Osservatorio Vesuviano, Naples, Italy and Dipartimento di Matematica e Fisica, University of Roma

Tre, Rome, Italy

b Italian Association of Volcanology, Italy

c Dipartimento di Scienze della Terra, University of Pisa, Pisa, Italy

Email: robertoscandone@gmail.com

Received: November 2019 – Accepted: December 2019

Abstract

The eruption of Vesuvius of 79 AD is the first large explosive eruption described in detail by Pliny the Younger.

The eruption began with a high eruptive column depositing a thick airfall pumice deposit to the South East of the

volcano, and it was followed by the emplacement of destructive glowing avalanches which destroyed the cities

of Pompeii, Herculaneum and Stabiae.

In this paper we re-evaluate the succession of the events based on the letters of Pliny, the volcanic deposit and

the extensive damages caused also by the earthquakes occurring during the eruption. We estimate the impact of

the synchronous seismic activity by evaluating its intensity and effects on the wider Campanian plain and draw-

ing novel isoseismal maps. We suggest that the strong intra-eruption seismicity conditioned the behavior of the

inhabitants of Pompeii during the eruption, compelling many of those, that were still in the houses to flee from

the collapsing buildings. We suggest also a different timing of the travel of Pliny the Elder from that proposed by

earlier authors We infer an earlier destruction of Herculaneum during the first day of the eruption, as witnessed

by the Elder during his travel from Misenum to the vesuvian region, which compelled him to deviate to Stabiae

where he died, the following day, a few minutes after the inhabitants of Pompeii.

Keywords: Vesuvius, Eruption of 79 AD, Pompeii, Herculaneum, Pumice Fall, Pyroclastic Density Cur-

rents, Earthquakes

1. Introduction

The eruption of Vesuvius of 79 AD is the

first large explosive eruption described in detail

by contemporary witnesses. Pliny the Younger

made an accurate narrative of the main features

of the eruption and nowadays, volcanologists

term Plinian the eruptions with the same charac-

teristics.

The eruption began with a high eruptive col-

umn depositing a thick airfall pumice deposit to

the South East of the volcano, and it was fol-

lowed by the emplacement of destructive glow-

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

ing avalanches, formerly called pyroclastic

flows and surges which are now defined Pyro-

clastic Density Currents, (PDC), which spread

almost radially from the volcano with a major

runout to the West, South and South East. Druitt

(1998), employs the term Pyroclastic Density

Currents to identify the flows of pyroclastic ma-

terial that range from expanded turbulent sus-

pensions to highly concentrated granular flow.

The eruption destroyed two major cities of

the Roman Empire, Pompeii and Herculaneum,

as well as country villas, suburbs, and dwellings

over a radius of more than 10-18 km from the

volcano. The former city was initially covered

by the airfall deposit 2.5-3.5 m thick, and later

by the emplacement of PDCs; Herculaneum was

mostly destroyed by PDCs.

Most of the vesuvian territory was buried un-

der a thick pyroclastic deposit and the memory

of the lost cities vanished until 1738, when the

first excavations revealed the extent of the erup-

tive destruction first at Herculaneum, and later

(1748) at Pompeii and surrounding areas.

Extensive damages on a wider area were also

likely caused by the seismic activity accompany-

ing the eruption.

The eruption is important not only from a

volcanological point of view, but also because it

froze the buried cities like a time capsule. The

houses, the artefacts of two entire cities along

with their inhabitants were preserved untouched

for centuries representing a formidable snapshot

of the daily life of a Roman city. The discovery

prompted the birth of archaeology with the con-

tinual improvement of the methods of excava-

tion and preservation of the uncovered artefacts

through trial and errors. Such process is still

continuing nowadays with difficulties and uncer-

tainties.

Several authors have made the reconstruction

of the eruptive sequence based on the stratigra-

phy of the products and the contemporary chron-

icles (Lirer et al., 1973; Sheridan et al., 1981;

Sigurdsson et al., 1982, 1985; Carey and Sig-

urdsson, 1987; Cioni et al., 1992, 1999; Gurioli

et al., 1999, 2002, 2005, 2007).

De Carolis et al., 2002, Luongo et al., 2003,

Giacomelli et al., 2003, De Carolis and Patricel-

li, 2013 made a detailed survey of the victims of

Pompeii, Herculaneum and suburbs trying,

whenever possible, to make a distinction be-

tween those found within the airfall deposits and

the many more found on top of it, within the

PDC sequence.

The scope of this paper is to assemble a novel

analysis of available information for a better un-

derstanding of the timing of eruption phenome-

na, of the loss of life and to better understand the

possible causes to the different behaviour of the

inhabitants in the different places and better as-

certain the extent of damages caused by the

eruption by revising the existing bibliography.

We in particular try to estimate the impact of the

synchronous seismic activity by evaluating its

intensity and effects on the wider Campanian

plain and make inferences on the role of intra-

eruption seismicity in conditioning the behav-

iour of the inhabitants of Pompeii during the

eruption.

2. The description of the eruption by

contemporaries

Pliny the Younger wrote two letters to the

historian Tacitus describing the events that led to

the death of his uncle, Pliny the Elder, because

of the eruption of Vesuvius. Recent critics (see

for example Guadagno, 1993; Eco, 1994) have

cast serious doubt on the reliance of most of

Pliny the Younger narrative, written mainly to

exalt the heroic role of the Elder as driven not

only by scientific curiosity but also by the at-

tempt to rescue the inhabitants living at the foot

of the exploding volcano. In the second letter the

role of the Younger is that of a true Roman citi-

zen observing the catastrophe with calm indif-

ference in contrast with that of his mother and

neighbors. However, there are too many descrip-

tions that are too precise and fitting the dynam-

ics of the eruption, that we believe they truly re-

flect the remembrance of a catastrophe that must

have remained carved in the memory of a young,

seventeen boy even 25 years after the event.

Recently it has been raised again the

longstanding discussion of the date of the erup-

tion. A dispute, dating back several centuries,

proposes different dates ranging between the

24th August to the 1st November. The former

date is taken by the most ancient codex of the

letter, Laurentianus Mediceus 47.36 (sec. IX)

which reports “Non. Kal. Sept(ember)” or the

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

24th of August; another codex reports

“Nov.(ember) Kal.” or the 1st November

(Stefani, 2006; Ricciardi, 2009). Recent archeo-

logical discoveries: the findings of fruits (nuts,

hazelnuts, pomegranates) (Figure 1) typical of

the Autumn, and the uncovering in the Casa del

Bracciale d’Oro of a coin of Emperor Titus with

a title (IMP XV) obtained only after September

of 79 AD, give credit to the later date (Stefani,

2006; Stefani and Borgoncino, 2007).

Figure 1. Archeological findings at Villa Regina

(Boscoreale) that suggest an Autumn date for the

eruption. a) Sealed jars containing grape must, b)

pomegranate, c) hazelnut, d) figs. Photo: Giaco-

melli and Scandone.

However, from a pure volcanological point of

view, the question is irrelevant, but for the dura-

tion of certain volcanic phenomena observed by

Pliny, as, in the Roman calendar, the duration of

the diurnal hour changed with the season, being

longer during the summer and shorter during the

autumn and winter. In any case the difference

between the sunrise for the different dates is in

the order of 1 hour.

In the following, we will make use of the

translation of J.B. Firth (1910) reporting only the

passages of volcanological relevance. In the Ap-

pendix we report a more extended version.

My uncle was stationed at Misenum, [Figure 2]

where he was in active command of the fleet,

with full powers. On the 24th of August, about

the seventh hour, my mother drew his attention

to the fact that a cloud of unusual size and

shape had made its appearance. He had been

out in the sun, followed by a cold bath, and af-

ter a light meal he was lying down and reading.

Yet he called for his sandals and climbed up to

a spot from which he could command a good

view of the curious phenomenon.

Figure 2. The Port of Misenum and, in the back-

ground, the internal lagoon, base of the fleet

(Classis Praetoria Misenensis Pia Vindex,) com-

manded by Pliny the Elder. Photo: Giacomelli and

Scandone.

Those who were looking at the cloud from some

distance could not make out from which moun-

tain it was rising – it was afterwards discov-

ered to have been Mount Vesuvius – but in like-

ness and form it more closely resembled a pine-

tree than anything else, for what corresponded

to the trunk was of great length and height, and

then spread out into a number of branches, the

reason being, I imagine, that while the vapour

was fresh, the cloud was borne upwards, but

when the vapour became wasted, it lost its mo-

tion, or even became dissipated by its own

weight, and spread out laterally. At times it

looked white, and at other times dirty and spot-

ted, according to the quantity of earth and cin-

ders that were shot up […]. He ordered a Li-

burnian galley to be got ready […].

Already ashes were beginning to fall upon the

ships, hotter and in thicker showers as they ap-

proached more nearly, with pumice-stones and

black flints, charred and cracked by the heat of

the flames, while their way was barred by the

sudden shoaling of the sea bottom and the litter

of the mountain on the shore. He hesitated for a

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

moment whether to turn back, and then, when

the helmsman warned him to do so, he ex-

claimed, “Fortune favours the bold; try to

reach Pomponianus”. The latter was at Stabi-

ae, separated by the whole width of the bay, for

the sea there pours in upon a gently rounded

and curving shore. . […]., and was waiting for

the wind which was blowing on shore to fall.

[Figure 3]

In the meantime, broad sheets of flame, which

rose high in the air, were breaking out in a

number of places on Mount Vesuvius and light-

ing up the sky, and the glare and brightness

seemed all the more striking owing to the dark-

ness of the night. […].

But by this time the courtyard leading to the

room he occupied was so full of ashes and

pumice-stones mingled together, and covered to

such a depth, that if he had delayed any longer

in the bedchamber there would have been no

means of escape. So, my uncle was aroused,

and came out and joined Pomponianus and the

rest who had been keeping watch. They held a

consultation whether they should remain in-

doors or wander forth in the open; for the

buildings were beginning to shake with the re-

peated and intensely severe shocks of earth-

quake and seemed to be rocking to and from as

though they had been torn from their founda-

tions. Outside again there was danger to be

apprehended from the pumice-stones, though

these were light and nearly burnt through, and

thus, after weighing the two perils, the latter

course was determined upon. […]

They placed pillows on their heads and secured

them with cloths, as a precauion against the

falling bodies. […] Then the flames, and the

smell of sulphur which gave warning of them,

scattered the others in flight and roused him.

Leaning on two slaves, he rose to his feet and

immediately fell down again, owing, as I think,

to his breathing being obstructed by the thick-

ness of the fumes and congestion of the stom-

ach, that organ being naturally weak and nar-

row, and subject to inflammation. When day-

light returned – two days after the last day he

had seen – his body was found untouched, un-

injured, and covered, dressed just as he had

been in life. The corpse suggested a person

asleep rather than a dead man.

We must recall that a different version of the

death of Pliny the Elder is given in the story of

his life by Suetonius in the De Viris Illustribus:

He lost his life in the disaster in Campa-

nia. He was commanding the fleet at Mi-

senum, and, setting out in a Liburnian

galley during the eruption of Vesuvius to

investigate the causes of the phenomenon

from nearer at hand, he was unable to re-

turn because of head winds. He was suffo-

cated by the shower of dust and ashes,

although some think he was killed by a

slave, whom he begged to hasten his end

when he was overcome by the intense heat

Figure 3. Course followed by Pliny the Elder after

leaving Misenum; firstly, toward Herculaneum or

Oplontis, and then after the early destruction of Her-

culaneum toward Stabiae. Arrows show the direction

of wind in the proximity of Vesuvius during the Pli-

nian phase (redrawn after image Nasa).

Was this the reason for the letters of Pliny the

Younger rehabilitating the figure of the uncle?

The second letter was written to report the

behavior of Pliny the Younger at Misenum.

But on that night the shocks were so intense

that everything, round us, seemed not only to be

disturbed, but to be tottering to its fall

[…]. It was now the first hour of the day, but

the light was still faint and weak. The buildings

all round us were beginning to totter, and,

though we were in the open, the courtyard was

so narrow that we were greatly afraid, and in-

deed sure of being overwhelmed by their fall.

[…]. We came to a halt when we had passed

beyond the buildings and underwent there

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

many wonderful experiences and terrors. For

although the ground was perfectly level, the ve-

hicles which we had ordered to be brought with

us began to sway to and from, and though they

were wedged with stones, we could not keep

them still in their places. Moreover, we saw the

sea drawn back upon itself, and, as it were, re-

pelled by the quaking of the earth. The shore

certainly was greatly widened, and many ma-

rine creatures were stranded on the dry sands.

On the other side, the black, fearsome cloud of

fiery vapour burst into long, twisting, zigzag

flames and gaped asunder, the flames resem-

bling lightning flashes, only they were of great-

er size. […].

Soon afterwards the cloud descended upon the

earth and covered the whole bay; it encircled

Capri and hid it from sight, and we could no

longer see the promontory of Misenum. […].

Then the ashes began to fall, but not thickly: I

looked back, and a dense blackness was rolling

up behind us, which spread itself over the

ground and followed like a torrent. [, when the

blackness of night overtook us, not that of a

moonless or cloudy night, but the blackness of

pent-up places which never see the light. […].

[…]. but the darkness came on again, and the

ashes once more fell thickly and heavily.

As said earlier we believe that the passages

that we reported are too close to actual volcanic

phenomena and confirmed by the stratigraphy of

deposits, to be only an invention. We will make

use of them and other facts to draw some infer-

ences on the eruption.

3. The reconstruction of the eruption

based on the stratigraphy of products

The uncontrolled urbanization of the vesuvian

area has destroyed many volcanic outcrops that

were still visible no more than forty years ago. At

the same time, the archeological digging of the

roman cities and the restoration of the collapsed

edifices has cancelled the deposits and their im-

pact on the urban network of the roman towns, as

well as the possibility to perform new analysis of

the effect of each single volcanic episode.

So, we must rely on the past detailed study that

were made on the eruption products (Lirer et al.,

1973; Sigurdsson et al., 1985; Cioni et al., 1992,

1999; Gurioli et al., 1999, 2002, 2005, 2007).

We mainly use those of Cioni et al. (1992,

1999) complemented by the detailed correlation

of the impacts on Herculaneum and Pompei

made by Gurioli et al. (1999, 2002, 2005, 2007).

Following Cioni et al., 1992, we use the term

Eruption Unit for a deposit that can comprise

one or more beds, emplaced by a single pulse or

phase characterized by a well-deﬁned eruptive

mechanism (Gurioli et al., 2002).

The generalized eruption stratigraphy of Cio-

ni et al., 1992,1999, is shown in Figure 4.

Figure 4. Stratigraphy of the products of the eruption

by Cioni et al., 1992.

The eruption began with a series of weak ex-

plosions (phreatomagmatic explosions) which

deposited a thin ash layer (EU1) mostly East of

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

the volcano with a maximum thickness of 5 cm.

The ash bed contains accretionary lapilli and

was likely produced by low level, vapor-rich ex-

plosions bended towards the east by low level

tropospheric wind (Sigurdsson et al., 1985)

(Figure 5).

Shortly after this event, but we cannot be sure

of the timing, there was the onset of the fully

convective, sustained eruption column growing

in height from 14 to 27 km (Carey and Sigurds-

son, 1985) which lasted for several hours (7h ac-

cording to Sigurdsson et al., 1985, 9h according

to Macedonio et al., 1988).

The column was dispersed to the South East

by the dominant jet stream and deposited a thick

layer of white pumices (EU2) with a thickness

of approximately 1 m near the volcano and at

Pompeii. At Herculaneum there is no trace of

this deposits because was upwind.

After the end of this phase, when the deposi-

tion of the gray pumice was already initiated,

occurred the first dramatic episode of the erup-

tion with the emplacement of a hot PDC

(EU2/3pf). The first PDC, due to a partial col-

lapse of the eruptive column, engulfed the city

of Herculaneum depositing a layer up to 1.5 m

thick, with building remains (roof tiles, columns,

and woods from the edifices; Figure 6). It likely

killed the inhabitants that were grouped on the

seashore (Sigurdsson et al., 1985; Gurioli et al.,

2002). The temperature of the flow was in the

order of 380 °C (Cioni et al. 2004) to 500 °C

(Mastrolorenzo et al. 2001) at Herculaneum.

This same PDC hit the villae in the Terzigno ar-

ea but did not reach Pompeii.

The emplacement of the first PDC was more

or less coincident with a change in composition

of the erupted magma (EU2/3pf). From that

moment onwards the reestablished sustained

eruption column, up to 32 km high, caused the

deposition of the grey pumice fallout bed. Dur-

ing this phase there were at least 4 partial col-

lapse of the column generating PDCs (EU3pf).

The pumice was deposited to the South-East,

(Fig.7, 8) and the PDC spread mostly to the

West, South and South East. These PDCs hit al-

so Oplonti and the country villas (Villae Rusti-

cae) at the foot of the volcano like the one in the

proximity of Boscoreale called Villa Regina.

Figure 5. Eruption deposits at Pompeii outside

Porta Nolana, resting directly on the Roman road.

Photo: Giacomelli and Scandone.

Figure 6. Deposits of the early pyroclastic density

currents at Herculaneum in the tunnel in the wall

facing the excavations. They were responsible for

the deaths inside the arcades. Photo Giacomelli

and Scandone.

The first PDC (EU3pf1) left a deposit 1 m

tick in Herculaneum, the following (EUpf2) is

up to 7 m thick in Herculaneum. The first 3 PDC

reached only the North Western periphery of

Pompeii leaving a thin ash deposit 2- to 7 cm

thick (Gurioli et al., 2007). The last one EU3pf,

generated by the final collapse of the eruption

column, left a deposit 4 to 30 cm thick at Pom-

peii.

The rapid withdrawal of magma from the

shallow reservoir, as often occurs during large

explosive eruption, caused a drop of pressure

within the magmatic system and the failure of

the rocks overlaying the magma chamber, as

signaled by the seismic activity reported by

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

Pliny the Younger, in the night between 24 and

25, i.e. during the entire EU3 phase, and increas-

ing at the end of this phase.

Figure 7. The correlation of the Eruption Units with

the sequence of the pyroclastic deposits in the ar-

chaeological excavations at Casa della Venere (regio

II, insula II), Pompeii. Source: modified after Gurioli

et al., 2007.

The failure of the rocks surrounding the

magma chamber, along with the surrounding

hydrothermal system, possibly caused some ear-

ly explosive interaction of magma and water

characterizing the following eruptive phases. It

is not clear if these early collapses and interac-

tion were also responsible of the column col-

lapses.

After a brief restoration of an eruption col-

umn (EU4f), the climactic phase of the eruption

occurred. The eruptive phase was heralded by

the occurrence of the most energetic, probably

lasting several minutes, seismic events reported

by Pliny the Younger early in the morning of 25.

The highly energetic seismic events were ac-

companied by the withdrawal of the sea that also

lasted minutes followed by a Tsunami. Soon af-

ter, the most powerful PDC (EU4pf) was report-

ed to engulf all the surroundings of the volcano

finally sealing the fate of Herculaneum and

Pompeii where it overpassed the city walls and

destroyed all the buildings laying above the lay-

ers of pumices (Sigurdsson et al., 1982; Cioni et

al., 2002; Gurioli et al., 2007) and extended till

Stabiae (where it left a more than 50 cm thick

deposit) and the Surrentine peninsula (Figure 9).

Two other PDC (EU5 and EU6) are mostly

found in the areas more proximal to the volcano.

The second one has abundant lithics of car-

bonate rocks and rocks forming the upper part of

the volcano (Cioni et al., 1992; the debris flow

deposit of Sigurdsson et al., 1985).

Figure 8. Distribution of the isopachs (lines of equal

thickness) of the deposits of the pumice air fall (in

cm). Blu for white pumices; Red for grey pumices.

Source: modified after Sigurdsson et al., 1985.

Finally, there was the emplacement of 2 other

PDC (EU7 and Eu8) which left an ash deposit in

Pompeii. The last one is rich in accretionary la-

pilli (pisolites) indicating abundant presence of

steam vapor in the eruptive cloud (phreatomag-

matic explosions). Overall the two phases EU2

and EU3 left a deposit of pumice 2.5 to 5 m

thick in Pompeii (Figure 8).

According to Macedonio et al., 1988, the two

phases of pumice fall lasted for 19 hours basing

on the estimate on the cumulative erupted mass

divided by of the mass eruption rate estimated

by the height of the eruption column (Carey and

Sigurdsson, 1985). However, the phases of col-

umn collapse and emplacement of intra-plinian

PDCs are not considered in this estimate of du-

ration. There is no possibility of estimating the

duration of the PDC phases basing on the thick-

ness of their deposits (Figure 9). According to

Sigurdsson et al., 1985, 19 hours was the total

duration of the eruption.

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

Figure 9. Isopachs of the cumulative thickness of the

pyroclastic density currents (in cm). Yellow maximum

extent of the deposits. Source: modified after Gurioli

et al., 2007.

4. The seismic activity before and

during the eruption of 79AD

On 5 February of 62 AD a devasting earth-

quake struck Pompeii and Herculaneum causing

widespread destruction. There is a longtime dis-

cussion on the date of this event due to the dif-

ferent dating provided by Seneca and Tacitus.

(63 AD) Seneca Naturales Questiones 6, 1,

An earthquake occurred on 5 February under

the consulship of Regulus and Verginius, which

caused widespread destruction and fear in

Campania, never safe from this occurrence,

(62 AD) Tacitus. Annals. 15, 22, Under the

same consuls the Gymnasium (of Naples) was

struck by a lightning and was burned, and the

same image of Nero melted. The famous city of

Campania, Pompeii was in large part destroyed

by an earthquake.

The majority of authors seems to prefer the

date of 62 AD.

Whichever was the date, the damages were

widespread at Pompeii and Herculaneum and mi-

nor at Nuceria and Naples. The extensive repara-

tions were still underway before the 79 AD at

Pompeii and Herculaneum. An inscription for the

restoration of a temple of Magna Mater at Hercu-

laneum is referred to Vespasianus in 76 AD.

Other testimonies are found in Pompeii like

an epigraph attesting the restoration of the tem-

ple of Isis, or bas-relief showing the effects of

the event (Figure 10).

Figure 10. Evidences of the 62 AD earthquake.

(top) Epigraph of Vespasianus (76 AD) for the

restoration of the temple of Magna Mater at Her-

culaneum (Napoli Museo Archeologico Na-

zionale); (Middle) Bas-relief in the house of

Cecilio Giocondo in Pompeii with the effects of

the earthquake (Exhibition in Rome, Scuderie del

Quirinale, 2019); (bottom) Epigraph for the resto-

ration of the Temple of Isis at Pompeii in the

name of the private citizen Popidius Celsinus

(Napoli Museo Archeologico Nazionale). Photos:

Giacomelli and Scandone.

The earthquake of 62 AD attracted most of

the interest of the researchers in the attempt to

understand the occurrence of precursors and

their effect on the cities of Pompeii and Hercu-

laneum (Boschi et al., 1995; Cubellis and Mar-

turano, 2002, 2006, 2013; Ruggeri et al., 2018).

One more earthquake probably struck the area in

64 AD causing damages at Naples as reported

by Tacitus.

Lesser attention has been devoted to the

seismicity occurring during the eruption (Boschi

et al., 1995; Cubellis and Marturano, 2006).

Pliny the Younger reports in his first letter

that for several days before (the eruption) the

earth had been shaken, but this fact did not cause

fear because this was a feature commonly ob-

served in Campania" (praecesserat per multos

dies tremor terrae, minus formidolosus quia

Campaniae solitus). It is difficult in the excava-

tions of Pompeii to understand if the repair

works, still underway, were in relation with the

earthquake of 62 or the damages caused by a

precursory earthquake swarm. Some rush inter-

ventions seem to precede the eruption by a little,

like a pole sustaining a jamb at Villa Regina, ex-

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

tensive repair works visible in many houses of

Pompeii, as to its water distribution network

(Figure 11).

Figure 11. A pole that supports a jamb at Villa Regi-

na. Photo: Giacomelli and Scandone.

As reported in the second letter of Pliny, dur-

ing the night of the first day of the eruption, the

houses of Misenum where shaken by earth-

quakes that caused much panic. Pliny the

Younger and his mother escaped in the open

heading northwards from the town of Misenum

and as soon as they had passed beyond the build-

ings, the most important and long-lasting earth-

quake crisis occurred shortly after day-break.

The seismic intensity they felt at Misenum was

such that wheeled charts on flat land were shak-

en back and forth even if chocks were placed

against the wheels. Sigurdsson et al. (1985) un-

derscore that in this same moment “Pliny the

Younger gives a vivid description of the prelude

to a tsunami… accompanying the earthquakes,

where the sea surges back upon itself “as though

forced back by the tremors of the earth” leaving

marine animals stranded”.

At the same time in his first letter, referring

to his uncle in Stabiae, by this time the courtyard

leading to the room he occupied was so full of

ashes and pumice-stones mingled together, and

covered to such a depth, that if he had delayed

any longer in the bedchamber there would have

been no means of escape. So, my uncle was

aroused, and came out and joined Pomponianus

[…] for the buildings were beginning to shake

with the repeated and intensely severe shocks of

earthquake and seemed to be rocking to and fro

as though they had been torn from their founda-

tions.

The cause of this earthquake swarm has been

understood only recently in the course of another

eruption occurred at Mt St Helens in 1980

(Scandone and Malone, 1985; Scandone and

Giacomelli, 2001). Often, during explosive erup-

tions there is an increase with time of magma

discharge rate (Figure 12).

Figure 12. Evolution with time of eruptive parameters

during the eruption of St. Helens in 1980. (top) In-

crease of the eruption rate; the closed squares indicate

the eruption rate estimated by the height of the erup-

tive column. (Bottom) Time-depth distribution of

earthquakes hypocenters during the eruption; note the

downward migration with time. Source: Scandone

and Giacomelli, 2001.

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

The discharge may be so high that the eruptive

column may not remain sustained and collapse to

the ground forming pyroclastic density currents.

At the same time the rapid discharge of magma

causes a sudden decompression in the magma

chamber with the failure of the rocks surrounding

it (Figure 13). The earthquakes resulting from this

syn-eruptive process are so much stronger as the

higher the eruption rate and the size of the cham-

ber (higher decompression rate and larger rock

mass involved in rock faulting).

High magnitude, shallow earthquakes have

been observed during several explosive erup-

tions in the last 100 years. Three main categories

of eruption-related earthquakes can be classified

as: i) induced by explosive plinian to sub-plinian

events, unrelated to caldera collapse; ii) incre-

mental calderas collapses related to mafic vol-

canic systems in which magma is laterally

drained from a shallow reservoirs; iii) Cata-

strophic caldera collapses induced by large vol-

ume explosive eruptions.

Examples of the category (I) are the 1914

Sakurajima eruption, Japan where an earthquake

M=7.1 occurred right after the main explosive

phase (Abe, 1992), the Nabro 2011 eruption (Er-

itrea) where earthquake up to M=5.8 to 5.8 oc-

curred during and immediately after the event

(Goitom et al., 2014). Example of category (ii)

are represented by the caldera formation of Fer-

nandina caldera (Galapagos - Ecuador) in 1968

where 8 earthquakes with M>5 occurred (Filson

et al., 1973) and very recently at Bardarbunga

2014-15 eruption (Iceland) where 18 earth-

quakes with magnitude comprised between

Mw=5.5 and Mw=5.8 occurred (Gudmundsson et

al., 2016). Examples of category (iii) are the cal-

dera collapse related Novarupta/Katmai erup-

tion, Alaska, 1912, where the main collapse of

Mount Katmai (5.5 km3 caldera volume) was

marked by the occurrence of a seismic crisis

which included a formidable sequence of M=

6.3, 7.0, 6.8 and 6.6 events (Abe, 1992). Syn-

eruptive seismicity is thus always present during

and immediately after explosive, plinian-type

events, but it is significantly augmented if a cal-

dera formation is involved and if the caldera col-

lapse occurs in a catastrophic manner rather than

in an incremental manner.

The eruption of Pinatubo is another well doc-

umented example of a large-scale explosive

event. The eruption began with a series of Plini-

an events at 13.09 of June 14th 1991, and culmi-

nated with a climactic phase at 13.42 of June

15th, terminating at 22.30 of the 15th (Wolfe and

Hoblitt, 1996). The erupted volume was in the

order of 5 km3 similar to that of Vesuvius 79 AD.

The earthquakes started to be felt after 15.39 of

June 15th. The national Earthquake Information

Center (NEIC) reported 29 events with a body

wave mb≥4.5 and 6 with a body wave magnitude

mb≥5; the largest magnitude was of 5.7. The

earthquakes were felt at a rate of 1 per minute at a

distance of 35 km from the volcano. On 16, the

rate of occurrence was of 150 earthquakes per

hour, with magnitudes ≥2.0 and rapidly decayed

on the following week (Mori et al., 1996).

The event produced also a small caldera, but

the volume of the structure is largely accounted

by lithic material which was erupted in large

volume during the last lithic-rich PDC.

Figure 13. Distribution of earthquakes occurred dur-

ing and after the eruptions of a) St Helens (USA) in

1980; b) Pinatubo Philippine , 1991. The dotted lines

indicate the location of the magma chamber. Source:

modified after Scandone and Acocella, 2007.

We can try to estimate the magnitude of the

earthquakes occurring during the eruption of 79

AD basing on the Intensity at different localities.

There are five epigraphs documenting the repa-

ration works made after the eruption of 79 AD

(Boschi et al., 1995) (Figure 14). Four are dedi-

cated to Emperor Titus between 80 and 81 AD,

and one to Emperor Domitianus. The first refers

to the restoration of edifices in Naples because

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

of earthquakes. It is an inscription in black stone

presently at the National Archeological Museum

of Naples (Renna, 1992).

The second one refers the reparation of a

clock in Sorrentum, destroyed by earthquakes,

currently at the Museum Correale of Sorrento.

The third one reports the restoration of a temple

in the proximity of Nola (Sampaolo, 1986). This

same author reports also another epigraph, from

Nola, now lost (CIL X, 1264), relative to the res-

toration of the collapsed Theater. The fourth,

dubious one, refers of generic damages at Saler-

no (Paci, 1991) The fifth inscription reported by

Johannowsky (1986) was found at Nocera (the

roman Nuceria Alfaterna) and is attributed to

Domitianus in the year 82 AD, even if his name

was cancelled for the Damnatio memoriae. It

pertains to the restoration of the Theater, col-

lapsed for the earthquakes.

It is interesting to note that, at difference

from those referring to the earthquake (terremo-

tu) of 62 AD, all these inscriptions make refer-

ence to earthquakes (terremotibus) possibly in-

dicating the many ones occurring, not only be-

fore but also during the eruption and not, as pre-

viously thought, also to the earthquake of 62.

We may estimate a Macroseseismic Magni-

tude from the Intensity, by applying the Bakun

and Wentworth’s (1997) relation for Ii (Intensi-

ty) and Ri (distance from the source) hypothesiz-

ing the epicenter below the Vesuvius

M = (Ii +1.72+0.0212 Ri)/1.4

Where Ii is the Intensity at place i and Ri is

the distance from the epicenter. However, for

shallow earthquakes, the values so estimated

may provide value in excess of 1 degree (Cubel-

lis and Marturano, 2002).

In Table 1 we report all the localities where it

is possible to make an estimate of the Intensity,

their distance from Vesuvius and the Macro-

seismic Magnitude corrected for the effect of

shallow depth.

There is a substantial convergence toward

corrected values between 5.3 and 6.28 with a

mean of 5.89 remarkably similar to the maxi-

mum magnitude of the earthquakes occurred at

Pinatubo. It must also be stressed that the result

so obtained is due to the cumulative effects of all

the seismic swarm occurred during the eruption.

Figure 14. Epigraphs pertaining to the earth-

quakes of 79 AD. A) Titus, restoration of a clock

in Sorrento (Museo Correale, Sorrento) (photo by

Giacomelli and Scandone), b) Titus restoration of

edifices in Naples (Museo Archeologico Na-

zionale, Napoli), (Photo by Sergio Izzo) c) Frag-

ments of an epigraph attributed to Titus in Saler-

no, (modified after Paci, 1991). d) Reproduction

of the epigraph of Domitianus for the restoration

of the Theater of Nuceria Alfaterna (after Joan-

nowski, 1986).

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

We can draw the isoseismal map obtained by

the macroseismic observations (Figure 15) and

compare them with the isoseismal map made by

Cubellis and Marturano (2002) for a 3.7-4.1

magnitude earthquakes occurred at Vesuvius in

1999. Although it is not entirely correct, a rough

estimate is obtained by increasing their isoseis-

mal lines of 4-5 degrees to fit the observed in-

tensities at the mentioned places.

We can observe that Pompeii and Herculane-

um are well within the Intensity IX-X isoseism

and must have suffered extensive damages not

only for the effects of the eruption, but also for

the earthquakes that, at Pompeii, resulted more

damaging because of the load of the pumices on

the roofs. We also stress that the earthquakes,

occurred during the eruption of 79 AD, are by

far larger than that occurred in 62 AD, with ef-

fects observed at a larger distance.

Place

stance Di

from

Vesuvius

(km)

Intensity

eismic Macros

Magnitude

Corrected

d)ctecorren(u

Source

Naples

13.9

VIII

.156

(7.15)

,CIL

1883

Nola

14.2

VIII

.166

16)(7.

, Joannhowski

1986

ceraNo

14.2

VIII

.166

(7.16)

et Boschi

al.,1995

oSorrent

.522

VIII

.286

(7.28)

Boschi et

al.,1995

Salerno

34.8

VII

.45

(6.4)

Paci,

1991

umMisen

29.27

VII

.35

(6.3)

Pliny

e Youngerth

Stabiae

15.92

VIII-VII

.85

(6.8)

Pliny

the Younger

Table 1. Localities where it is possible to make an estimate of the Intensity and Macroseismic Magnitude cor-

rected for the effect of shallow depth.

Figure 15. Isoseismal map for the earthquakes of 79 AD estimated by the actual intensities (left); drawn accord-

ing to the damages observed, modifying the isoseismal map of Cubellis and Marturano, 2002 (right).

17 Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

5. The Victims of the Eruption

De Carolis et al., 1996 made a detailed inven-

tory of the victims found within the city of Pom-

pei basing on the excavation reports made since

1748. This study was used by Luongo et al.,

2003, and Giacomelli et al., 2003, to infer the

possible causes of death during the eruption. De

Carolis and Patricelli, 2013, have extended the

inventory to the places outside Pompeii compris-

ing Herculaneum, Oplontis, the port area of

Pompeii and Stabiae.

Although it is not possible a detailed posi-

tioning of the human remains within the volcan-

ic deposit, it is possible to make a rough distinc-

tion between the bodies found within the pumice

deposits and those found embedded in the ash of

the PDCs. In Pompeii, and in the immediate sur-

rounding areas, there is evidence that a substan-

tial number of people were found above the

pumice layer and within the ash of the PDCs.

In 1863, the archeologist Giuseppe Fiorelli

devised a method to obtain the cast of the vic-

tims found in the ashes above the pumices,

where the percolation of human tissues with

time left a void in the ash that preserved the

form of the body. By injecting liquid gypsum

into the void, it was possible to obtain the image

of the dead (Figure 16).

The cast of the body of the victims permitted

to crystallize the last moments of life of the fugi-

tives of Pompeii. This procedure was not possi-

ble for the dead in the pumice or wherever the

lack of pumices below the bodies, did not allow

the slow percolation of human tissues and the

preservation of the form of the body in the ash.

Figure 16. One of the first cast made by Fiorelli at

Pompeii, in 1863 in the vicolo degli Scheletri,

now in the house of Sirico. Photo: Giacomelli and

Scandone.

A detailed study of the findings was made for

a few outcrops, including those called Casa dello

Stabiano in Pompeii where the casts of the vic-

tim are found above the pumice layer and the

PDC unit EU3pf and possibly buried within

EU4Pf (Luongo et al., 2003; Santacroce, 2018)

(Figure 17)

Photographs from the time of the excavation

in the 1960s, in the nearby outcrop called Orto dei

Fuggiaschi (Figure 18), suggest that the casts of

the victims, before being removed from their

original position, were at the same stratigraphic

level as many other found in the ashes above the

pumices, like the bodies in the courtyard of the

Casa del Criptoportico.

Figure 17. The casts of victims in Casa dello Sta-

biano at Pompei from above and the side; they

rest directly over the first PDC reaching Pompeii

above the pumice fall deposit. Note also the

change of color of pumice from white to grey.

Photo: Giacomelli and Scandone.

In the past, there was no such attention to a

stratigraphic excavation that could position the

victims at a particular stratigraphic level, and af-

ter the casts were made, they were always re-

moved from their original position.

Unfortunately, such practice is still in use

nowadays, even if attempt to define the strati-

graphic position is performed when volcanolo-

gists are present at the excavations.

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

The number of victims remains uncertain

even for the use, until the middle of 1800 of

throwing the bones with the excavated material.

The majority of the victims found in the pum-

ices are within houses, often men with children

and women, some pregnant, and only a few are

found outside suggesting that they were compelled

to remain indoor. Many of the bodies have broken

bones suggesting collapse of the houses. Victims

found in the ash have often the so-called boxer

posture common for the victims in hot pyroclastic

flows because caused by the muscle contraction

for heat (Figure 19). The total number of victims is

1800.

Figure 18. The digging of the cast at the so-called Or-

to dei Fuggiaschi at Pompeii in 1961 from a RAI

movie of the time. The casts are at the same strati-

graphic level of those of Casa dello Stabiano. Source:

RAI.

Figure 19. Comparison of victims found in pyro-

clastic flows. (Up) casts of victims of Pompeii.

(photo by Giacomelli and Scandone), (Bottom)

Victims in the eruption of Merapi Volcano in In-

donesia (after Schiffman, 2011), and at Mt Lam-

ington in Papua New Guinea (after Taylor, 1958).

All have the typical posture of the boxer due to

the contraction of muscle for the heat.

To these, it must be added an unspecified num-

ber of human remains of the order 100, not directly

described in excavation reports but simply indicat-

ed as findings of human bones, so that the total

number of found victims ascend to 1900.

In Table 2, we provide a resume of the

detailed tables of De Carolis et al., 1998, and De

Carolis and Patricelli, 2013, summarizing the

findings at Pompeii and outside.

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

yitLocal

within es Bodi

the Pumice

housesinside

Bodies within

the Pumice

outside houses

s within Bodie

the ashes

houses inside

hin Bodies wit

the ashes

houses outside

Totals

Pompeii

345

334

316

1044

uburbsPompei s

170

Boscoreale

tiScafa

Terzigno

AnnunziataTorre

Herculaneum

311

493

aStabi

101

reCastellamma

oGragnan

eAntonio Abat S.

Totals

8001

Table 2. The findings at Pompeii and outside regarding bodies within the Pumice inside houses, bodies within

the Pumice outside houses, Bodies within the ashes inside houses, Bodies within the ashes outside houses

6. The damages and the survivors

The eruption and the associated earthquakes

caused widespread destruction at Pompeii, Her-

culaneum, Oplontis, Stabiae and in all the vesu-

vian territory. Extensive damages were pro-

duced, after the eruption, by numerous mud-

flows caused by the mobilization of loose ashes

by rainstorms (Lirer et al., 2001). Some of them

are still visible in Torre Annunziata (Figure 20).

Besides the effects of the PDC, all the area to the

South east of the volcano was covered by a loose

sheet, up to 3 m thick, of pumices extending

well into the steep slopes of the Sorrentine pen-

insula. Rapid erosional processes driven by steep

slopes subsequently reworked the soft and loose

pyroclastic material leading to tens of metres of

valley filling, alluvial fan growth, and fan delta

formation (Cinque and Robustelli, 2009). Some

of these events, occurred immediately after the

eruption, eventually buried Roman villas in S.

Antonio Abate and Positano and lasted up to 120

years after the eruption (Cinque and Robustelli,

2009).

The earthquakes hit areas which had not been

affected seriously by the PDC like Naples, Nola

and Nuceria causing extensive damages that

were repaired in the following years as attested

by the numerous epigraphs. As at Pompeii, at

Stabiae, Sorrento and Salernum, the earthquakes

effect was aggravated by the blanket of pyro-

clastic deposit that had accumulated on the roofs

of the edifices. Still years later, during Adrian

empire, the reopening of the road between Nuce-

ria and the restored Stabia, was possible only by

building walls that prevented the sliding of pum-

ices (Renna, 1992).

Figure 20. Deposits of lahar (mudflows) topping

the grey pumice and a roman wall. Photo: Gia-

comelli and Scandone.

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

Immediately after the eruption, the emperor

Titus, as attested by Suetonius, nominated two

ex-consuls (Curatores restituendae Campaniae)

to superintend the repairs works and the legal

question arising for the deaths of so many citi-

zens.

The disaster left a great impression on the

contemporaries which transpire in the works of

poets and in the mention of historians.

We recall the poet Martial which first men-

tions the cities of Pompei and Herculaneum

Here is the Vesuvius, once green with shady

vineyards, here a precious grape was over-

flowing the tubs; Bacchus loved these leaps

more than the hills of Nisa, on this mountain

the Satyrs in the past dissolved their dances;

this, of Sparta more pleasing, was the seat of

Venus (Pompeii), this was the place renowned

for the name of Hercules (Herculaneum). Now

everything lies submerged in flames and in

sad lapillus: now they would not want the

gods that they had been allowed to exercise so

much power here.

The restoring of Naples and surrounding

places is recalled in the work Silvae by the Nea-

politan poet Statius (probably composed be-

tween 89 and 96 AD). In Silvae III, 5, address-

ing to his wife Claudia:

The Vesuvian peak, the tempest of fire from

that ominous height, have not so utterly cowed

and drained our cities of men. They still stand

strong in their sons. Westward the halls of

Dicarcheus (Pozzuoli) that arose at Phoebus’

ordinance, the haven and the shore that wel-

comes all the world northward the towers that

rival the expanse of imperial Rome, the towers

that Capys filled with his Teucrian pilgrims.

And there too is our own Parthenope (Naples),

that can scarce shelter her own people, and

has scant room for settlers. […] it be your

pleasure to repair to steaming Baiae’s allur-

ing beach, or to the haunted shrine of the in-

spired Sibyl. The cape that bears upon it for

monument the Trojan’s oar or the flowing

vineyards of Bacchus-haunted Gaurus and the

homes of the Teleboae, where the Pharus, to

guide anxious mariners, uplifts a beacon

bright as the nomad Queen of night; or to

those Surrentine ridges, dear to sturdy Lyae-

us, that Pollius, my friend, honours above all

with his dwelling place; to the healing waters

of Inarime (Ischia) or to Stabiae reborn

(Translated by Slater, 1908).

How many were the survivors of the eruption

that may have left Pompeii and Herculaneum be-

fore or even during the eruptions? The answer is

not simple because we do not know the exact

number of inhabitants before the eruption to

compare with that of the deaths. What should be

taken in mind is that these cities had suffered

from the effects of the earthquakes of 62 and 64

and possibly several other before the eruption.

The city of Pompeii was the site of repairing

works and many of the houses were not inhabit-

ed and many temples were still to be repaired,

and the same water distribution system was not

working (Dickman, 2005).

Probably the estimate of 15000-20000 people

(the capacity of the amphitheater) living only in

Pompeii is an overestimate. We believe that, at

most, such estimate of 15000-20000, should be

addressed to the all population living in the Ve-

suvian suburbs, which compares, for example,

with a population of 40000 living in the same

area in 1631. As often has been the case during

volcanic eruptions, the precursory seismicity is

so relevant that even people not knowing any-

thing of volcanoes flee the site at the first signs

of unrest, as was the case during the Vesuvius

eruption of 1631 (Braccini, 1632). The victims

are those too scared to take any decision or pre-

vented by minors or disabled relatives. We be-

lieve that the approximately 1900 bodies found,

and perhaps as many as another 1000 in the un-

earthed territory, may represent the maximum

number of people that died during the eruption

(4000 during the 1631) which ascend to a per-

centage ranging between 15 and 19% of the total

population which compare with the 10% loss

during the 1631 eruption.

As for the refuges, an important clue where

they escaped, has been recently provided by the

fundamental work of Steve L. Tuck (2019). He

examined the known names of the inhabitants of

Pompei and Herculaneum and accurately com-

pared with those of the surrounding cities where

those names were not present before the 79 AD.

The not surprising result is that the inhabitants

of Herculaneum and Pompeii found refuge

mostly at Puteoli, Neapolis, Cumae, and Ostia,

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

all to the north of the destroyed towns. A pre-

dominance of names coming from Pompeii was

found at Cumae and Puteoli, whereas in Nea-

polis there was evidence of families from both

cities. It should be recalled that in Neapolis there

was an area called Regio Herculanensis. Sup-

porting evidence for a sudden increase of the

population at Neapolis, Puteoli and Cuma is also

the building of new infrastructures and temples

in the period after the eruption, in many cases

with the imperial support (Tuck, 2019).

We suggest that the flight to the cities to the

north of the volcano was driven by the extensive

damages made by the airfall deposit to the

South-East, which required a longer recovering

time because of the loss of arable land, and the

frequent landslides and mud flow affecting the

entire Sorrento and Salerno area.

They went to the North also because it was

the path, they followed the most before the erup-

tion, and in any case the one that most rapidly

led away from Vesuvius. To the east, towards

the Apennines, they were at that time places of

difficult access.

7. Discussion and Conclusions

In order to assess the timing of the destruc-

tion of the vesuvian suburbs it is necessary to

correlate the deposition of the eruption products

with the known time of the travel of Pliny the

Elder and the occurrences observed by Pliny the

Younger at Misenum. Such timing has been

proposed by Sheridan et al., 1981, Sigurdsson et

al., 1982, Macedonio et al., 1988, Scandone and

Giacomelli, 2000, Giacomelli and Scandone,

2002, among the others. Here we draw a differ-

ent scenario based on the Letters of Pliny, the

succession of events proposed by Cioni et al.,

2002, Gurioli et al., 2002, 2005, 2007, the suc-

cession of earthquakes felt at Misenum and Sta-

biae, the distribution of victims in all the vesuvi-

an district.

An important point, not previously fully un-

derlined, is the early destruction of Herculaneum

by the arrival of EU2/3pf at the end of the phase

of white pumice fall deposition. We believe that

this dramatic event was witnessed by Pliny the

Elder during his travel to the devasted region

(Figure 21).

Already ashes were beginning to fall upon the

ships, hotter and in thicker showers as they

approached more nearly […] while their way

was barred by the sudden shoaling of the sea

bottom and the litter of the mountain on the

shore (iam vadum subitum, ruinaque montis

litora obstantia).

As it has already been pointed out by Ric-

ciardi (2009), the term ruina montis was used by

the Romans to indicate the quarrying operation

when landslides were caused by the disruption

of galleries. We believe that the shoaling and the

litter of the mountain are the evidence of the first

PDC engulfing all the southern side of the vol-

cano, where possibly was also located Rectina

Villa, and that the Elder may have observed such

occurrence and the consequent death of all the

inhabitants living at Herculaneum.

Other have suggested that the shoal may have

been caused by the pumice on the sea, but they

must have been even more abundant toward Sta-

biae where they were blown by the stratospheric

winds.

Figure 21. Dead found in the arcades of the beach

of Herculaneum and the boat turned over on the

beach of Herculaneum. Photo: Giacomelli and

Scandone.

With the favor of the wind, Pliny the Elder

may have reached Stabiae in a short while. Ac-

tually, we believe that he was compelled to land

in Stabiae because of the wind. Many authors

suppose that the distribution of the air fall de-

posit suggests a North-Western wind blowing

also at sea level. We recall that the direction of

air-fall deposits is governed by the Jet Stream at

the tropopause (about 10 km asl); this does not

imply the same wind at sea level. A somehow

more significant information about the wind di-

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

rection in the lower part of the troposphere is of-

fered by the dispersal direction of the basal ash

fall deposit. The ash is clearly dispersed east-

ward indicating that in the early morning of 24,

the wind in the first 5 km was blowing from

west to east. If the same wind direction was pre-

sent at sea level it would have further facilitated

the travel of Pliny the Elder from Misenum to-

wards the Rectina’s villa and later on would

have made almost impossible for the Stabians to

flee via sea. However, during large explosive

eruption with a sustained eruption column, a

strong air influx, necessary to maintain the

buoyancy of the column, occurs at the base of

the volcano. The Plinian eruption is likely to

have caused strong hurricane winds toward the

volcano and the ships travelling toward Pompei

may have been engulfed in this storm.

This scenario is confirmed by the variation of

the thickness of the air-fall pumice (Sigurdsson

et al., 1985) (Figure 22, bottom) which shows a

relative thinning toward the volcano with respect

to Pompeii, justified by the blowing of strong

winds toward the volcano up to a distance of at

least 10-12 km Thus the pumices were partly re-

cycled with the eruption column and their depo-

sition was hindered.

A possible occasional pause, at the moment

of the first eruption collapse, may have permit-

ted to Pliny the Elder to seek refuge in the near-

est safe anchorage of Stabiae, in a moment when

it was possible to see also the place in the pause

of the pumice fall. This has occurred approxi-

mately 7-9 hours after the beginning of the erup-

tion. We are compelled to suggest that the be-

ginning of the eruption has not occurred at 1 pm

as observed by the Pliny at Misenum, but some

hours before as already suggested by Sigurdsson

et al., 1982, 1985.

The timing of the travel is strongly con-

strained by the time necessary to Pliny the Elder

to reach a high place where observe the eruption

at Misenum, to go back to the naval base, order

the preparation of the quadriremes and the time

necessary to reach Stabiae. This last part could

have lasted more than 7.3 and 5.5 hours at an

average speed of 3-4 knots. So, a conservative

estimate of the time needed to arrive to Stabiae

is between 11-9 hours.

Figure 22. Mechanism of deposition from a Plinian

eruption column. The deposits are dispersed by the

jet stream, but the deposition in the proximal areas is

governed by the low-level winds rushing toward the

volcano with a relative thinning of the deposit (drawn

by the authors). In the lower part is shown the thick-

ness of the deposit of the Plinian fall of the 79 AD

eruption. Source: Sigurdsson et al., 1985.

The beginning hour depends on the exact

date of the eruption, if in Summer or Autumn,

because we infer that the arrival at Stabiae oc-

curs shortly before sunset. On 24 October, at this

latitude the sunset occurs at 6:17 pm and dawn is

at 7:31 am. On 24 August, the sunset occurs at

7.50 pm and dawn is at 6:20 am. The start of the

eruption is possibly between 9 and 10 in the

morning.

The night was troubled by earthquake shock

of increasing violence that occurred mostly dur-

ing the eruption of the grey pumice and the em-

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

placement of the four EU3pf. By this time all the

inhabitants living to the west of Pompei may

have already died as a consequence of the earlier

PDCs.

Only those inside the houses at Pompei and

its suburbs, and Stabiae were still living, pro-

tected by the distance from the volcano, the wall

of the city, and the shelter, barricaded inside the

houses (Figure 23).

However, the increasing collapses of the

roofs loaded by pumice and the terrifying in-

creasing earthquakes compelled these inhabit-

ants, that had otherwise survived the first phase

of the eruption, to attempt fleeing from the safe

refuge of the houses.

This scenario is also suggested by the behav-

ior of Pliny the Elder at a greater distance from

the volcano:

But by this time the courtyard leading to the

room he occupied was so full of ashes and

pumice-stones mingled together, and covered

to such a depth, that if he had delayed any

longer in the bedchamber there would have

been no means of escape. […]. They held a

consultation whether they should remain in-

doors or wander forth in the open; for the

buildings were beginning to shake with the re-

peated and intensely severe shocks of earth-

quake and seemed to be rocking to and fro as

though they had been torn from their founda-

tions. Outside again there was danger to be

apprehended from the pumice-stones, though

these were light and nearly burnt through, and

thus, after weighing the two perils, the latter

course was determined upon. […]. They

placed pillows on their heads and secured

them with cloths, as a precaution against the

falling bodies. Elsewhere the day had dawned

by this time, but there it was still night, and

the darkness was blacker and thicker than any

ordinary night.

So, they left the houses because of earth-

quakes during the fall of the pumice. If the dura-

tion of the grey pumice fall, lasted 10 hours

(Macedonio et al., 1988), the end of the EU3

phase would occur at 6 am (if a summer date is

considered) or 1 hour and half earlier if the Au-

tumn date is considered. In both cases, to fit

Pliny the Younger timing (one hour after sun-

rise), we must hypothesize a longer duration for

the EU3 phase, justified by the duration of the

EU3pf events.

Figure 23. The entrance to the Efebo House was

blocked by a pole that prevented the pumice from

breaking through the door. Photo: Giacomelli and

Scandone.

At Misenum, shortly one hour after the dawn,

Pliny the Younger reports the occurrence of the

strongest and long-lasting seismic events along

with the occurrence of a Tsunami.

We saw the sea drawn back upon itself, and,

as it were, repelled by the quaking of the earth

[…] the black, fearsome cloud of fiery vapour

burst into long, twisting, zigzag flames and

gaped asunder, the flames resembling light-

ning flashes, only they were of greater size.

[…].

Soon afterwards the cloud descended upon the

earth and covered the whole bay; it encir-

cled Capri and hid it from sight, and we could

no longer see the promontory of Misenum.

At this same moment, Pliny the Elder was en-

gulfed by the hot avalanche reaching Stabiae and

the western Sorrentine peninsula.

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

At Pompeii, people made the same choice, at

the same moment as Pliny the Elder. We specu-

late that, the temporary decline of eruptive activ-

ity (cessation of the pumice fallout) combined

with the occurrence of the strongest, caldera-

forming, seismic events (M=5.8-6.2), likely

caused the simultaneous and widespread col-

lapse of edifices. It was this sudden and frighten-

ing event which eventually induced the survivals

to flee their shelters seeking safety outside. They

had however to make the travel above the depos-

it of EU3pfi and EU3pf, that offered a difficult

path to the presumed safety despite the still hot

deposit above meters of non-consolidated pum-

ices. Unfortunately, at that point, they were

swept away by the arrival of the EU4pf which

occurred after a brief pumice fall of grey pumice

and when the caldera collapse reached the sur-

face activating a massive release of pyroclastic

material from multiple vents.

Our reconstruction finds a striking similarity

with what happened during the only plinian-type

eruption of Vesuvius for which we have a de-

tailed historical account: the 1631 eruption.

The reconstruction of the eruption made us-

ing deposit stratigraphy and the historical chron-

icles enabled Rosi et al. (1993) to highlight the

occurrence of two main climactic eruptive phas-

es: the plinian phase initiated in the morning of

16 December associated to the emplacement of a

pumice fallout and the pyroclastic flow phase

which occurred in the morning of 17 December.

The two eruption phases were separated by

hours of less energetic explosive activity and the

occurrence of short-lived earthquakes. The sec-

ond climactic phase was shortly preceded by the

occurrence of a 5’-long, highly energetic earth-

quake along with a widespread withdrawal of

sea in the gulf of Napoli (tsunami). The earth-

quake culminated with the sinking of the cone

which was witnessed by people in Napoli (Brac-

cini, 1631), the formation of a 1200m diameter

caldera and the emission of PDCs (Carafa,

1632). Both the 79 and the 1631 eruptions pro-

duced a climax of the hazard and the largest

number of victims as a result of earthquakes and

PDC’s produced in connection with the caldera

collapse (Orlandi, 1632).

The occurrence of the most energetic seismic

crisis in coincidence with caldera collapse in-

duced by plinian eruption is in turn in excellent

agreement with what have been observed in sim-

ilar events around the World in the past 100yrs.

As it regards the tsunami origin of both 79 and

1631, they share the same characteristics and

appear to be generated from slumping of sea-

floor sediments in the gulf of Napoli mobilized

by the same caldera-forming earthquake as also

suggested by Sigurdsson et al. (1985).

It is certainly surprising that more than 1000

peoples had survived for so long within the

houses of the city of Pompeii in a truly dramatic

atmosphere, during the night, under the shower

of pumice lapilli with lightnings and earthquakes

rocking the edifices. Only the increasing vio-

lence of the earthquakes drove part of them out-

side the houses in search of a difficult safety.

The progressive increase of the violence had

been signaled by the increasing size of the pumice

and lithics falling on the city, but this knowledge

was only recognized 2000 years later.

We can end this note by citing the words of

Braccini (1632) during the eruption of 1631

Perituri non recipunt consilia (Those that are to

die do not accept advise); we hope that these

events may serve as a warning for the future.

Acknowledgements

We acknowledge the thoughtful reviews by anony-

mous reviewers. We thank Carlo Doglioni for point-

ing out the problem of cooperation between volcan-

ologists and archaeologists from which originated the

present work.

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Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

Appendix

Letters of Pliny the Younger (Epistulae VI,

16, 20)

The first letter and the Fate of Pliny the Elder

My uncle was stationed at Misenum, where he

was in active command of the fleet, with full

powers. On the 24th of August, about the sev-

enth hour, my mother drew his attention to the

fact that a cloud of unusual size and shape had

made its appearance. He had been out in the

sun, followed by a cold bath, and after a light

meal he was lying down and reading. Yet he

called for his sandals and climbed up to a spot

from which he could command a good view of

the curious phenomenon. Those who were look-

ing at the cloud from some distance could not

make out from which mountain it was rising – it

was afterwards discovered to have been Mount

Vesuvius – but in likeness and form it more

closely resembled a pine-tree than anything

else, for what corresponded to the trunk was of

great length and height, and then spread out in-

to a number of branches, the reason being, I

imagine, that while the vapour was fresh, the

cloud was borne upwards, but when the vapour

became wasted, it lost its motion, or even be-

came dissipated by its own weight, and spread

out laterally. At times it looked white, and at

other times dirty and spotted, according to the

quantity of earth and cinders that were shot up

[…]. He ordered a Liburnian galley to be got

ready […]. He was just leaving the house when

he received a written message from Rectina, the

wife of Tascus, who was terrified at the peril

threatening her - for her villa lay just beneath

the mountain, and there were no means of es-

cape save by shipboard – begging him to save

her from her perilous position. So, he changed

his plans, and carried out with the greatest for-

titude the task, which he had started as a schol-

arly inquiry.

He had the galleys launched and went on board

himself, in the hope of succouring, not only

Rectina, but many others, for there were a

number of people living along the shore owing

to its delightful situation. He hastened, there-

fore, towards the place whence others were

fleeing, and steering a direct course, kept the

helm straight for the point of danger, so utterly

devoid of fear that every movement of the loom-

ing portent and every change in its appearance

he described and had noted down by his secre-

tary, as soon as his eyes detected it. Already

ashes were beginning to fall upon the ships,

hotter and in thicker showers as they ap-

proached more nearly, with pumice-stones and

black flints, charred and cracked by the heat of

the flames, while their way was barred by the

sudden shoaling of the sea bottom and the litter

of the mountain on the shore. He hesitated for a

moment whether to turn back, and then, when

the helmsman warned him to do so, he ex-

claimed, “Fortune favours the bold; try to

reach Pomponianus”. The latter was at Stabi-

ae, separated by the whole width of the bay, for

the sea there pours in upon a gently rounded

and curving shore. Although the danger was

not yet close upon him, it was none the less

clearly seen, and it travelled quickly as it came

nearer, so Pomponianus had got his baggage

together on shipboard, and had determined up-

on flight, and was waiting for the wind which

was blowing on shore to fall. My uncle sailed in

with the wind fair behind him, and embraced

Pomponianus, who was in a state of fright,

comforting and cheering him at the same time.

[…]. [Figure 3].

In the meantime, broad sheets of flame, which

rose high in the air, were breaking out in a

number of places on Mount Vesuvius and light-

ing up the sky, and the glare and brightness

seemed all the more striking owing to the dark-

ness of the night. My uncle, in order to allay the

fear of his companions, kept declaring that the

country people in their terror had left their fires

burning, and that the conflagration they saw

arose from the blazing and empty villas. Then

he betook himself to rest and enjoyed a very

deep sleep […]. But by this time the courtyard

leading to the room he occupied was so full of

ashes and pumice-stones mingled together, and

covered to such a depth, that if he had delayed

any longer in the bedchamber there would have

been no means of escape. So, my uncle was

aroused, and came out and joined Pompon-

ianus and the rest who had been keeping watch.

They held a consultation whether they should

remain indoors or wander forth in the open; for

the buildings were beginning to shake with the

repeated and intensely severe shocks of earth-

quake and seemed to be rocking to and from as

though they had been torn from their founda-

tions. Outside again there was danger to be

apprehended from the pumice-stones, though

these were light and nearly burnt through, and

thus, after weighing the two perils, the latter

course was determined upon. With my uncle it

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

was a choice of reasons which prevailed, with

the rest a choice of fears.

They placed pillows on their heads and secured

them with cloths, as a precaution against the

falling bodies. Elsewhere the day had dawned

by this time, but there it was still night, and the

darkness was blacker and thicker than any or-

dinary night. This, however, they relieved as

best they could by a number of torches and oth-

er kinds of lights. They decided to make their

way to the shore, and to see from the nearest

point whether the sea would enable them to put

out, but it was still running high and contrary.

A sheet was spread on the ground, and on this

my uncle lay, and twice he called for a draught

of cold water, which he drank. Then the flames,

and the smell of sulphur which gave warning of

them, scattered the others in flight and roused

him. Leaning on two slaves, he rose to his feet

and immediately fell down again, owing, as I

think, to his breathing being obstructed by the

thickness of the fumes and congestion of the

stomach, that organ being naturally weak and

narrow, and subject to inflammation. When

daylight returned – two days after the last day

he had seen – his body was found untouched,

uninjured, and covered, dressed just as he had

been in life. The corpse suggested a person

asleep rather than a dead man.

The second letter and the behavior of Pliny

the Younger at Misenum.

After my uncle had set out, I employed the re-

mainder of the time with my studies, for I had

stayed behind for that very purpose. Afterwards

I had a bath, dined, and then took a brief and

restless sleep. For many days previous there

had been slight shocks of earthquake, which

were not particularly alarming, because they

are common enough in Campania. But on that

night the shocks were so intense that every-

thing, round us, seemed not only to be dis-

turbed, but to be tottering to its fall. My mother

rushed into my bedchamber, just as I myself

was getting up in order to arouse her if she was

still sleeping. We sat down in the courtyard of

the house, which was of smallish size and lay

between the sea and the buildings […]. It was

now the first hour of the day, but the light was

still faint and weak. The buildings all round us

were beginning to totter, and, though we were

in the open, the courtyard was so narrow that

we were greatly afraid, and indeed sure of be-

ing overwhelmed by their fall. So that decided

us to leave the town. We were followed by a

distracted crowd, which, when in a panic, al-

ways prefers someone else’s judgment to its

own as the most prudent course to adopt, and

when we set out these people came crowding in

masses upon us, and pressed, and urged us

forward. We came to a halt when we had

passed beyond the buildings and underwent

there many wonderful experiences and terrors.

For although the ground was perfectly level,

the vehicles which we had ordered to be

brought with us began to sway to and from, and

though they were wedged with stones, we could

not keep them still in their places. Moreover,

we saw the sea drawn back upon itself, and, as

it were, repelled by the quaking of the earth.

The shore certainly was greatly widened, and

many marine creatures were stranded on the

dry sands. On the other side, the black, fear-

some cloud of fiery vapour burst into long,

twisting, zigzag flames and gaped asunder, the

flames resembling lightning flashes, only they

were of greater size. […].

Soon afterwards the cloud descended upon the

earth and covered the whole bay; it encircled

Capri and hid it from sight, and we could no

longer see the promontory of Misenum. […].

Then the ashes began to fall, but not thickly: I

looked back, and a dense blackness was rolling

up behind us, which spread itself over the

ground and followed like a torrent. "Let us turn

aside," I said, "while we can still see, lest we be

thrown down in the road and trampled on in

the darkness by the thronging crowd." We were

considering what to do, when the blackness of

night overtook us, not that of a moonless or

cloudy night, but the blackness of pent-up plac-

es which never see the light. […].

A gleam of light now appeared, which seemed

to us not so much daylight as a token of the ap-

proaching fire. The latter remained at a dis-

tance, but the darkness came on again, and the

ashes once more fell thickly and heavily. We

had to keep rising and shaking the latter off us,

or we should have been buried by them and

crushed by their weight. […]. At length the

blackness became less dense and dissipated as

it were into smoke and cloud; then came the re-

al light of day, and the sun shone out, but as

blood red as it appears at its setting. Our still

trembling eyes saw that everything had been

transformed, and covered with a deep layer of

ashes, like snow. Making our way back to Mi-

senum, we refreshed our bodies as best we

could, and passed an anxious, troubled night,

hovering between hope and fear. But our fears

Roberto Scandone, Lisetta Giacomelli, Mauro Rosi

were uppermost, for the shocks of earthquake

still continued, and several persons, driven

frantic by dreadful prophecies, made sport of

their own calamities and those of others. For

our own part, though we had already passed

through perils, and expected still more to come,

we had no idea even then of leaving the town

until we got news of my uncle.

ResearchGate has not been able to resolve any citations for this publication.

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