VESUVIUS
The old Greeks and Romans had but little knowledge of volcanoes. They
only knew the volcanic mountains in the Mediterranean Sea. Here there
are three volcanic regions:--one in the neighborhood of Naples; one
including Sicily and the neighboring islands, and the other that of
the Grecian Archipelago.
Some idea can be had of these three regions from a map of the
Mediterranean shown in Fig. 12. The principal volcanoes are Vesuvius,
Etna, Stromboli, and Vulcano, a mountain, by the way, that gave its
name to all volcanic mountains. In this chapter we will describe the
volcano of Vesuvius, the most active, though by no means the largest
of the volcanoes of the Mediterranean.
But, before doing this, it will be well first to describe briefly the
volcanic districts surrounding Vesuvius.
As shown in Fig. 13, this district includes Vesuvius, Procida, and
Ischia.
[Illustration: FIG. 12. THE MEDITERRANEAN]
Ischia is a small island measuring about five miles from east to west,
and three miles from north to south. There were such terrific volcanic
eruptions on this island long before the Christian Era, that several
Greek colonies were forced to abandon it. A colony established long
afterwards, about 380 B. C., by the king of Syracuse also
had to depart. Strabo, the Grecian geographer (born about 63 B.
C.), states that, according to tradition, terrific earthquakes
occurred on the island a little before his time, and its principal
mountain threw out large quantities of molten rock, which flowed into
the sea. At the time of this eruption there were earthquake waves in
the sea, the waters of which slowly receded, leaving large portions
of the bottom uncovered, and rushing, afterwards, violently over
the land, caused great destruction. It was during this disturbance,
so Strabo asserts, that the island of Procida was formed by being
violently torn from Ischia.
[Illustration: FIG. 13. THE VOLCANIC DISTRICT AROUND VESUVIUS]
The Phlegræan Fields was a name given by the ancients to some of the
lowlands in the neighborhood of Naples; they were believed to be under
the special protection of the Roman gods. When the frequent earthquake
shocks shook these fields, the Roman people believed that conflicts
were taking place between their gods and slumbering giants confined in
the regions below the surface.
It is more than probable that Mt. Vesuvius has always been the centre
of these volcanic disturbances. Long before the Christian Era,
however, Vesuvius, or Somma, the name given to the old crater that
then occupied the summit of the mountain, had been an extinct crater.
Indeed, it had been so quiet that the people who lived on its slopes
did not appear to know they were living on the slopes of a slumbering
volcano. Their knowledge of volcanic mountains must have been very
limited, for this mountain with the huge pit at its summit had all
the appearance of a volcanic crater. When they climbed to the top of
the mountain, which, of course, they frequently did to look after the
vineyards they were cultivating on the slopes, and looked down into
the deep pit from the rocks on its edge, they could see at the bottom
of a great central pit three miles in diameter, a lake, with room here
and there to enable one to walk along its borders. The walls of the
precipice were covered with luxuriant vines.
When we say that none of the people even suspected that Vesuvius had
ever been in a state of eruption, we must except some of their learned
men. For both Diodorus Siculus, a native of Sicily, who lived about
10 B. C., and wrote an Universal History, containing some
forty volumes, of which only about one-third remain, and Strabo, the
Geographer, pointed out in a general manner, that Vesuvius, and much
of the surrounding country, looked as if it had been eaten by fire.
Then, too, a Roman philosopher who lived between A. D. 1 and
A. D. 64, spoke of Vesuvius being "a channel for the eternal
fire!"
Let us now endeavor to obtain some idea of the appearance of this
region a short time before A. D. 79, when Vesuvius burst
forth in a terrific eruption. The slopes of the mountain were covered
with the rich vegetation that characterizes this part of Italy.
When most volcanic ashes and lava have been exposed for some time to
the atmosphere they make a very fertile soil. Now, this soil on the
slopes of Vesuvius made the vineyards that covered the mountain slopes
and the fields for miles around its base, bear very plentifully,
so that the people lived very comfortably. Here and there on the
slopes of the mountain large towns like Herculaneum and Pompeii had
long been established, while, in the distance, was the large city of
Naples. Besides these there were numerous populous towns and villages
scattered here and there over the plain or on the lower mountain slope.
You have all probably read of the Roman gladiator, Spartacus.
Spartacus was a Thracian by birth, and while a shepherd had been taken
prisoner by the Romans and sold to a trainer of gladiators at Capua.
Chaffing under the tyranny of the Romans, who forced him to fight in
the arena with men and beasts, he revolted against his masters, and
with a band of some seventy followers, fled to a mountain fastness in
the crater of Vesuvius. Proud Rome sent a few men to recapture him,
with scourges for his punishment, but they were beaten by Spartacus.
Every day dissatisfied men like himself escaped from the Romans and
joined his ranks. Rome sent a larger body of men against Spartacus,
but they also were beaten. At last, recognizing the gravity of the
position, the Roman Prætor, Clodius, was sent against Spartacus with
an army of some three thousand men. Clodius caught Spartacus in the
crater and guarded the only space by which it seemed possible for
Spartacus to escape. Using the vines that covered the precipitous
walls of the crater, Spartacus did escape, and falling unexpectedly
on the armies of Clodius, routed them. After this victory, Spartacus
with an army of over 100,000 men overran southern Italy, and sacked
many of the cities of the Roman Campania. During this time Spartacus
defeated one Roman army after another, until finally, in the year 71
B. C., Crassus was sent against him and vainly endeavored
to conquer him. Being unsuccessful, Crassus urged the Roman Senate
to recall Lucullis from Asia and Pompey from Spain, and finally poor
Spartacus was cut down in a fight he made against Crassus and Lucullis.
But let us come to the great eruption of Vesuvius in A. D.
79. The people living on the slopes of Vesuvius were not without
plenty of warnings of the dreadful catastrophe that was coming. As
early as A. D. 63 there was a great earthquake that shook the
country far beyond Naples. In Pompeii, then a flourishing city, the
Temple of Isis was so much damaged that it had to be rebuilt.
Even if the earthquake shocks had not foretold the coming eruption,
there were other signs. The height of water in the wells decreased.
Springs that had never before been known to fail, dried up completely.
These changes, as we well know, were due to the red hot lava being
slowly forced up from great depths into the tube connected with the
crater.
The earthquake shocks continued at irregular intervals for sixteen
years, until, on the 25th of August, A. D. 79, about one
o'clock in the afternoon, Vesuvius burst forth in the terrible
eruption that destroyed the towns of Pompeii and Herculaneum. Pompeii
was a seaport town situated near the mouth of the River Sarno,
about fifteen miles southeast of Naples. It was a beautiful place,
containing many splendid temples. Its people for the greater part
lived luxuriously, for Pompeii was the summer resort of the richer
people of Naples, some of whom lived there during the hottest months
of the year.
Herculaneum, the other town, was nearer Naples, only five miles from
the city. It was also, like Pompeii, a beautiful town, and contained
many splendid buildings. In each town there were magnificent baths and
a large theatre. The inhabitants spent so much of their time in the
open air, or in the baths, that it was not necessary for them to build
very large houses. The houses, however, were well built, and though
generally consisting of practically a single story, were provided with
all the luxuries that great wealth could command.
On August 25th, A. D. 79, severe earthquake shocks again
visited this part of the world and Vesuvius suddenly threw up from
its crater an immense column of black smoke, which, rising high in
the air, spread out in the form of a huge mushroom, or, perhaps, more
like the umbrella pine tree of the neighborhood. Rapidly spreading on
all sides, the smoke soon completely shut out the light of the sun,
and wrapped the earth in an inky darkness, except for a red glare from
columns of molten rock that rushed out of the crater.
From the dark cloud immense quantities of red hot stones, pumice, and
volcanic ashes descended on the earth. At the same time there fell
a deluge of rain, caused by the sudden condensation of the enormous
amount of water vapor that was thrown out from the crater during the
eruption. Fortunately, very few of the people were killed in either of
the cities of Pompeii and Herculaneum, although some bodies were found
in the ruins. Most of the people escaped through the darkness and
gloom, continuing to flee from the city for at least three days.
Both cities were covered so deep with ashes or mud that the tops of
the tallest buildings were no longer visible. Pompeii was buried by
showers of ashes or volcanic cinders, and Herculaneum mainly by vast
floods of aqueous lava.
So completely were these cities covered that their very existence was
at last forgotten. It is true that Titus, who was then Emperor of
Rome, endeavored to clear away the ashes and rebuild Pompeii, but the
task was so great that he finally abandoned it.
During the year 1592, the architect Fontana, while superintending the
building of an aqueduct, came across some ancient buildings. At a much
later date, in 1713, some workmen, while digging a well in the village
of Portici, uncovered three marvellously beautiful marble statues. In
the year 1738, the same well was dug deeper, when traces of the old
theatre of Herculaneum were discovered. Some effort was then made to
excavate the city and many of the public buildings and private houses
were uncovered, and statues, mosaics, wall paintings, and charred
manuscripts of papyrus were found. A few of these have been unrolled
and deciphered, but owing to the difficulty of doing this, without
destroying them, the greatest number still remain unread.
In 1860, the Italian Government began a systematic excavation of the
buried cities, and now both Pompeii and Herculaneum are thrown open to
the sunlight so that one can walk through the old streets, and look
into the houses, in which, before A. D. 79, the people lived
so happily.
Many interesting stories are told about the discoveries that were
made during the government excavations. The skeleton of one of the
inhabitants was found grasping a money bag. He might have escaped,
but had gone back to get his money. He got it, but remained with it.
In another place, the skeletons of a number of people were found in
an underground room or cellar of a house, where were also found some
mouldy bread and empty water flasks. Instead of leaving the city,
which they might have done, they had retreated to the underground
room for safety, but the fine volcanic dust drifted in and suffocated
them.
The younger Pliny, the historian, has given an excellent account of
some features of this great eruption. It appears that his uncle was
stationed with the Roman fleet, in the Bay of Naples, at the time of
the eruption. He describes the dark cloud of ashes that was formed
over Vesuvius. He refers to the rapidity with which it spread, and
to the showers of ashes, cinders, and stones that it rained down on
the earth. His uncle, the elder Pliny, landed on the coast, and was
afterwards killed by a cloud of sulphurous vapor that swept down the
side of the mountain.
The following letter from the younger Pliny, describing his flight
with his mother from Misenum, is quoted from Dana's "Characteristics
of Volcanoes."
"It was now seven o'clock [on the morning of August 25th],
but the light was still faint and doubtful. The surrounding
buildings had been badly shaken, and although we were in
an open spot [a little yard between his uncle's house and
the sea], the space was so small that the danger of a
catastrophe from falling walls was great and certain. Not
till then did we make up our minds to go from the town....
When we were free from the buildings we stopped. There we
saw many wonders and endured many terrors. The vehicles we
had ordered to be brought out kept running backward and
forward, though on level ground; and even when blocked
with stones they would not keep still. Besides this, we
saw the sea sucked down and, as it were, driven back by
the earthquake. There can be no doubt that the shore had
advanced on the sea, and many marine animals were left high
and dry. On the other side was a dark and dreadful cloud,
which was broken by zigzag and rapidly vibrating flashes of
fire, and yawning showed long shapes of flame. These were
like lightning, only of greater extent....
"Pretty soon the cloud began to descend over the earth
and cover the sea. It enfolded Capreæ and hid also the
promontory of Misenum." ... The flight was continued.
"Ashes now fell, yet still in small amount. I looked
back. A thick mist was close at our heels, which followed
us, spreading out over the country, like an inundation."
... Turning from the roar in order to avoid the fleeing,
terror-stricken throng, they rested. "Hardly had we sat
down when night was over us--not such a night as when there
is no moon and clouds cover the sky, but such darkness as
one finds in close-shut rooms. One heard the screams of
women, the fretting cries of babes, and shouts of men....
"Little by little it grew light again. We did not think
it the light of day, but a proof that the fire was coming
nearer. It was indeed fire, but it stopped afar off; and
then there was darkness again, and again a rain of ashes,
abundant and heavy, and again we rose and shook them off,
else we had been covered and even crushed by the weight....
At last the murky vapor rolled away, in disappearing smoke
or fog. Soon the real daylight appeared; the sun shone out,
of a lurid hue, to be sure, as in an eclipse. The whole
world which met our frightened eyes was transformed. It was
covered with ashes white as snow."
Young Pliny and his mother returned to Misenum, and survived the
perils to which they were exposed.
It was during this eruption that a large part of the old crater was
blown off the mountain by the tremendous force at work.
There have been many eruptions of Vesuvius since the great eruption
of A. D. 79. One of these occurred during the reign of Severus,
A. D. 203. It was during this eruption that an additional part of the
old crater of Somma was blown away.
Another great eruption occurred A. D. 472. Then great
quantities of volcanic dust were thrown up into the air, and falling,
covered practically all parts of Europe, producing darkening of the
sun and great fear as far as the city of Constantinople.
But what was perhaps a still greater eruption occurred during December
of 1631. This eruption spread great quantities of ashes over the
country for hundreds of miles around, and great streams of mud rushed
down the slopes of the mountain. Buccini gives the following account
of this eruption:
"The crater was five miles in circumference, and about
1,000 paces deep. Its sides were covered with brushwood,
and at the bottom there was a plain on which cattle grazed.
In the woody parts wild boars frequently harbored. In one
part of the plain, covered with ashes, were three small
pools, one filled with hot but bitter water; another with
water saltier than the sea, and a third with water that
was hot but tasteless. But at length these forests and
grassy plains were consumed, being suddenly blown into the
air and their ashes scattered to the winds. In December,
1631, seven streams of lava poured at once from the crater
and overflowed several villages, on its flanks, and at the
foot of the mountain. Reisna, partly built over the ancient
city of Herculaneum, was consumed by the fiery torrent.
Great floods of mud were as destructive as lava. This is
no unusual occurrence during these catastrophes for such
is the violence of the rains produced by the evolution of
aqueous vapors that torrents of water descend the cone and
become charged with impalpable volcanic dust, and rolling
among ashes, acquire sufficient consistency to deserve the
ordinary appellation of aqueous lava."
Of course, you will understand that we have given only a few of
the most notable of the eruptions of Mt. Vesuvius. Since the yea
A. D. 1500 there have been no less than fifty-six recorded
eruptions, that of the year 1857 being especially violent.
Omitting these eruptions we at last come to the great recent eruption
of 1872.
Fortunately, the eruption of 1872, as well as still more recent
eruptions that have occurred, have been more accurately described than
have most volcanic eruptions, for the Italian Government, recognizing
the value to the natives of Italy of a knowledge of what was going on
at the crater of Vesuvius, has maintained for the past thirty years
an observatory on the western part of the mountain. This observatory
has been placed in charge of Prof. Luigi Palmieri, a well-known
student of volcanoes and earthquakes. At this place records are kept
of the behavior of the volcano, of all earthquake disturbances, as
well as other phenomena. At the same time, by the use of photography,
excellent pictures have been obtained showing the appearance of the
sky during an eruption.
Vesuvius had been in a quiet state from November, 1848, to the year
1871, when small quantities of lava flowed continuously for several
months. Again, early in 1872, other quiet eruptions of lava continued
for weeks at a time. Finally, on April 26th, of that year, a violent
explosive eruption occurred. The following account has been taken from
Palmieri's report, entitled, "The Eruption of Vesuvius in 1872."
On April 23d the recording earthquake instruments, the seismographs,
were greatly affected. On the evening of the 24th lava streams flowed
down the cone in various directions. These streams were continued
on the 25th and the 26th, so that on the night of the 26th the
observatory lay between two streams of molten lava that threw out so
much heat that the glass windows in the observatory were cracked,
and a scorching smell was quite perceptible in the rooms. The cone
of the mountain was deeply fissured, lava escaping freely from all
the fissures, so that the molten rock appeared to ooze from over its
entire surface, or as Palmieri expressed it, "Vesuvius sweated fire."
This great cracking or fissuring of the cone was accompanied by the
opening of two large craters at the summit, that discharged, with a
great noise, immense clouds of steam, dust, lapilli, and volcanic
bombs. These latter are very curious and consist of masses of soft
lava that are thrown high into the air by the outrushing columns of
steam. Being rotated or spun, as they rise in the air, they assume a
spherical shape. Some of these volcanic bombs were thrown to a height
estimated by Palmieri to have been nearly 4,000 feet above the top of
the mountain. When the height of a projectile is known, the velocity
with which it left the opening from which it was projected or thrown
can be estimated, so that the volcanic bombs must have left the crater
at a velocity of about 600 feet per second.
On the 27th, in the evening, the lava streams ceased flowing, but the
dust and lapilli continued to fall during the 28th and the 29th. On
the 30th the detonations decreased and by the 1st of May the eruption
was entirely over.
Palmieri calculated that the quantity of molten rock thrown out during
this eruption was sufficient to cover an area of about 1.8 square
miles to an average depth of about thirteen feet.
As we can see from the above descriptions, the volcanic activity of
Vesuvius is characterized by long periods of rest followed by periods
of activity. The periods of rest are measured by years, and often by
centuries; the periods of activity by days or hours.
But Vesuvius was not to have a long period of rest after its eruption
of 1872. On the contrary, shortly after the great disaster of
Martinique in 1906, it again became active, and on the 5th of April,
1906, began throwing large blocks of lava out of its central cone, and
on the next day began to throw out large streams of lava, which, on
April 7th, destroyed a village in the neighborhood. At the same time
rumbling sounds were heard, and violent earthquake shocks shattered
the windows of the houses.
Professor Matteucci, the present director of the Vesuvius Observatory,
made the following report on April the 8th.
"The eruption of Vesuvius has assumed extraordinary
proportions. Yesterday and last night the activity of the
crater was terrific, and is increasing. The neighborhood
of the observatory is completely covered with lava.
Incandescent rocks are being thrown up by the thousands, to
a height of 2,400 feet or even 3,000 feet, and falling back
form a large cone. Another stream of lava has appeared....
The noise of the explosion and of the rocks striking
together is deafening. The ground is shaken by strong and
continuous seismic movements, and the seismic instruments
[instruments employed to record the time, direction, and
intensity of earthquake movements] threaten to break. It
will probably be necessary to abandon the observatory,
which is very much exposed to the shocks. The telegraph is
interrupted, and it is believed the Funicular railroad has
been destroyed."
On April 9th Matteucci made the following report:
"The explosive activity of Vesuvius, which was so great
yesterday, and was accompanied by very powerful electric
discharges, diminished yesterday afternoon. During the
night the expulsion of rocks ceased, but the emission of
sand increased, completely enveloping me and forming a
red mass from six to ten centimeters deep, which carried
desolation into these elevated regions. Masses of sand
gliding along the earth, created complete darkness until
seven o'clock. Several blocks of stone broke windows in the
observatory. Last night the earthquake shocks were stronger
and more frequent than yesterday, and displaced the seismic
apparatus. Yesterday afternoon and this morning, torrents
of sand fell."
On April 10th Matteucci sent the following report:
"Last night was calm, except for a few explosions of
considerable force from time to time. At four o'clock this
morning the explosions became more violent. The seismic
instruments recorded strong disturbances."
The eruption of Vesuvius of 1906 was especially noted for the great
quantities of sand and ashes thrown out of the crater. The amount
of sand that fell on the roof of the market house at Monti Olivetto
was so great that the roof fell in. In this eruption there were some
six lava streams that poured down the mountain. The most formidable
of these was that which descended towards Torre Annunziata. Here it
stopped just short of the wall of the cemetery outside of the town.
During this eruption of Vesuvius, as in previous eruptions, clouds of
volcanic dust collected in the air, shutting off the light of the sun.
Naples was in a state of semi-darkness. The roofs of the houses were
covered to a depth of several inches with an exceedingly fine reddish
dust. In some places this dust had drifted into heaps fully a yard in
depth.