The San Francisco Calamity

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It may seem strange that so dangerous a neighborhood should be
inhabited. But so it is. Though Pompeii, Herculaneum and Stabiae lie
buried beneath the mud and ashes belched out of the mouth of Vesuvius,
the villages of Portici and Revina, Torre del Greco and Torre del
Annunziata have taken their place, and a large population, cheerful
and prosperous, flourishes around the disturbed mountain and over the
district of which it is the somewhat untrustworthy safety-valve.

It is thus that man, in his eagerness to cultivate all available parts
of the earth, dares the most frightful perils and ventures into the most
threatening situations, seeking to snatch the means of life from
the very jaws of death. The danger is soon forgotten, the need of
cultivation of the ground is ever pressing, and no threats of peril seem
capable of restraining the activity of man for many years. Though the
proposition of abandoning the Island of Martinique has been seriously
considered, the chances are that, before many years have passed, a
cheerful and busy population will be at work again on the flanks of Mont
Pelee.


MOUNT ETNA


On the eastern coast of the Island of Sicily, and not far from the
sea, rises in solitary grandeur Mount Etna, the largest and highest of
European volcanoes. Its height above the level of the sea is a little
over 10,870 feet, considerably above the limit of perpetual snow.
It accordingly presents the striking phenomenon of volcanic vapors
ascending from a snow-clad summit. The base of the mountain is
eighty-seven miles in circumference, and nearly circular; but there is
a wide additional extent all around overspread by its lava. The lower
portions of the mountain are exceedingly fertile, and richly adorned
with corn-fields, vineyards, olive-groves and orchards. Above this
region are extensive forests, chiefly of oak, chestnut, and pine, with
here and there clumps of cork-trees and beech. In this forest region are
grassy glades, which afford rich pasture to numerous flocks. Above the
forest lies a volcanic desert, covered with black lava and slag. Out of
this region, which is comparatively flat rises the principal cone, about
1,100 feet in height, having on its summit the crater, whence sulphurous
vapors are continually evolved.

The great height of Etna has exerted a remarkable influence on its
general conformation: for the volcanic forces have rarely been of
sufficient energy to throw the lava quite up to the crater at the
summit. The consequence has been, that numerous subsidiary craters and
cones have been formed all around the flanks of the mountain, so that it
has become rather a cluster of volcanoes than a single volcanic cone.

The eruptions of this mountain have been numerous, records of them
extending back to several centuries before the Christian era, while
unrecorded ones doubtless took place much further back. After the
beginning of the Christian era, and more especially after the breaking
forth of Vesuvius in 79 A. D., Etna enjoyed longer intervals of repose.
Its eruptions since that time have nevertheless been numerous--more
especially during the intervals when Vesuvius was inactive--there being
a sort of alternation between the periods of great activity of the two
mountains; although there are not a few instances of their having been
both in action at the same time.


SIMILARITY IN ETNA'S ERUPTIONS


There is a great similarity in the character of the eruptions of Etna.
Earthquakes presage the outburst, loud explosions follow, rifts and
bocche del fuoco open in the sides of the mountain; smoke, sand, ashes
and scoriae are discharged, the action localizes itself in one or more
craters, cinders are thrown up and accumulate around the crater and
cone, ultimately lava rises and frequently breaks down one side of the
cone where the resistance is least; then the eruption is at an end.

Smyth says: "The symptoms which precede an eruption are generally
irregular clouds of smoke, ferilli or volcanic lightnings, hollow
intonations and local earthquakes that often alarm the surrounding
country as far as Messina, and have given the whole province the name
of Val Demone, as being the abode of infernal spirits. These agitations
increase until the vast cauldron becomes surcharged with the fused
minerals, when, if the convulsion is not sufficiently powerful to force
them from the great crater (which, from its great altitude and the
weight of the candent matter, requires an uncommon effort), they explode
through that part of the side which offers the least resistance with a
grand and terrific effect, throwing red-hot stones and flakes of fire to
an incredible height, and spreading ignited cinders and ashes in every
direction."

After the eruption of ashes, lava frequently follows, sometimes rising
to the top of the cone of cinders, at others disrupting it on the least
resisting side. When the lava has reached the base of the cone it begins
to flow down the mountain, and, being then in a very fluid state, it
moves with great velocity. As it cools, the sides and surface begin to
harden, its velocity decreases, and after several days it moves only
a few yards an hour. The internal portions, however, part slowly with
their heat, and months after the eruption clouds of steam arise from the
black and externally cold lava-beds after rain; which, having penetrated
through the cracks, has found its way to the heated mass within.


THE ERUPTION OF 1669


The most memorable of the eruptions of Etna was that which elevated the
double cone of Monte Rossi and destroyed a large part of the city
of Catania. It happened in the year 1669, and was preceded by an
earthquake, which overthrew the town of Nicolosi, situated ten miles
inland from Catania, and about twenty miles from the top of Etna. The
eruption began with the sudden opening of an enormous fissure, extending
from a little way above Nicolosi to within about a mile of the top of
the principal cone, its length being twelve miles, its average breadth
six feet, its depth unknown.

We have a more detailed account of this eruption than of any preceding
one, as it was observed by men of science from various countries. The
account from which we select is that of Alfonso Borelli, Professor of
Mathematics in Catania.

From the fissure above mentioned, he says, there came a bright light.
Six mouths opened in a line with it and emitted vast columns of smoke,
accompanied by loud bellowings which could be heard forty miles off.
Towards the close of the day a crater opened about a mile below the
others, which ejected red-hot stones to a considerable distance, and
afterward sand and ashes which covered the country for a distance of
sixty miles. The new crater soon vomited forth a torrent of lava which
presented a front of two miles; it encircled Monpilieri, and afterward
flowed towards Belpasso, a town of 8,000 inhabitants, which was speedily
destroyed. Seven mouths of fire opened around the new crater, and
in three days united with it, forming one large crater 800 feet in
diameter. All this time the torrent of lava continued to descend, it
destroying the town of Mascalucia on the 23d of March. On the same day
the crater cast up great quantities of sand, ashes and scoriae, and
formed above itself the great double-coned hill now called Monte Rossi,
from the red color of the ashes of which it is mainly composed.


VILLAGES AND CITIES BURIED


On the 25th very violent earthquakes occurred, and the cone above the
great central crater was shaken down into the crater for the fifth time
since the first century A. D. The original current of lava divided
into three streams, one of which destroyed San Pietro, the second
Camporotondo, and the third the lands about Mascalucia and afterward the
village of Misterbianco. Fourteen villages were altogether destroyed,
and the lava flowed toward Catania. At Albanelli, two miles from the
city, it undermined a hill covered with cornfields and carried it
forward a considerable distance. A vineyard was also seen to be floating
on its fiery surface. When the lava reached the walls of Catania, it
accumulated without progression until it rose to the top of the wall, 60
feet in height, and it then fell over in a fiery cascade and overwhelmed
a part of the city. Another portion of the same stream threw down 120
feet of the wall and flowed into the city.

On the 23d of April the lava reached the sea, which it entered as a
stream 600 yards broad and 40 feet deep. The stream had moved at the
rate of thirteen miles in twenty days, but as it cooled it moved
less quickly, and during the last twenty-three days of its course, it
advanced only two miles. On reaching the sea the water, of course,
began to boil violently, and clouds of steam arose, carrying with them
particles of scoriae. Towards the end of April the stream on the west
side of Catania, which had appeared to be consolidated, again burst
forth, and flowed into the garden of the Benedictine Monastery of San
Niccola, and then branched off into the city. Attempts were made to
build walls to arrest its progress.

An attempt of another kind was made by a gentleman of Catania, named
Pappalardo, who took fifty men with him, having previously provided them
with skins for protection from the intense heat and with crowbars to
effect an opening in the lava. They pierced the solid outer crust of
solidified lava, and a rivulet of the molten interior immediately gushed
out and flowed in the direction of Paterno, whereupon 500 men of that
town, alarmed for its safety, took up arms and caused Pappalardo and his
men to desist. The lava did not altogether stop for four months, and two
years after it had ceased to flow it was found to be red hot beneath the
surface. Even eight years after the eruption quantities of steam escaped
from the lava after a shower of rain.


THE STONES EJECTED


The stones which were ejected from the crater during this eruption
were often of considerable magnitude, and Borelli calculated that the
diameter of one which he saw was 50 feet; it was thrown to a distance
of a mile, and as it fell it penetrated the earth to a depth of 23 feet.
The volume of lava emitted during the eruption amounted to many millions
of cubic feet. Ferara considers that the length of the stream was at
least fifteen miles, while its average width was between two and three
miles, so that it covered at least forty square miles of surface.

Among the towns overflowed by this great eruption was Mompilieri.
Thirty-five years afterward, in 1704, an excavation was made on the site
of the principal church of this place, and at the depth of thirty-five
feet the workmen came upon the gate, which was adorned with three
statues. From under an arch which had been formed by the lava, one
of these statues, with a bell and some coins, were extracted in good
preservation. This fact is remarkable; for in a subsequent eruption,
which happened in 1766, a hill about fifty feet in height, being
surrounded on either side by two streams of lava, was in a quarter of
an hour swept along by the current. The latter event may be explained by
supposing that the hill in question was cavernous in its structure,
and that the lava, penetrating into the cavities, forced asunder their
walls, and so detached the superincumbent mass from its supports.

It is not by its streams of fire alone that Etna ravages the valleys and
plains at its base. It sometimes also deluges them with great floods of
water. On the 2d of March, 1755, two streams of lava, issuing from the
highest crater, were at once precipitated on an enormous mass of very
deep snow, which then clothed the summit. These fiery currents ran
through the snow to a distance of three miles, melting it as they
flowed. The consequence was, that a tremendous torrent of water rushed
down the sides of the mountain, carrying with it vast quantities of
sand, volcanic cinders and blocks of lava, with which it overspread the
flanks of the mountain and the plains beneath, which it devastated in
its course.

The volume of water was estimated at 16,000,000 cubic feet, it forming
a channel two miles broad and in some places thirty-four feet deep,
and flowing at the rate of two-thirds of a mile in a minute. All the
winter's snow on the mountain could not have yielded such a flood,
and Lyell considered that it melted older layers of ice which had been
preserved under a covering of volcanic dust.


ETNA IN 1819


Another great eruption took place in 1819, which presented some
peculiarities. Near the point whence the highest stream of lava
issued in 1811, there were opened three large mouths, which, with loud
explosions, threw up hot cinders and sand, illuminated by a strong glare
from beneath. Shortly afterwards there was opened, a little lower down,
another mouth, from which a similar eruption took place; and still
farther down there soon appeared a fifth, whence there flowed a torrent
of lava which rapidly spread itself over the Val del Bove. During the
first forty-eight hours it flowed nearly four miles, when it received a
great accession. The three original mouths became united into one large
crater, from which, as well as from the other two mouths below, there
poured forth a vastly augmented torrent of lava, which rushed with great
impetuosity down the same valley.

During its progress over this gentle slope, it acquired the usual crust
of hardened slag. It directed its course towards that point at which Val
del Bove opens into the narrow ravine beneath it--there being between
the two a deep and almost perpendicular precipice. Arrived at this
point, the lava-torrent leaped over the precipice in a vast cascade, and
with a thundering noise, arising chiefly from the crashing and breaking
up of the solid crust, which was in a great measure pounded to atoms by
the fall; it throwing up such vast clouds of dust as to awaken an alarm
that a fresh eruption had begun at this place, which is within the
wooded region.

A very violent eruption, which lasted more than nine months, commenced
on the 21st of August, 1852. It was first witnessed by a party of
English tourists, who were ascending the mountain from Nicolosi in order
to see the sunrise from the summit. As they approached the Casa Inglesi
the crater commenced to give forth ashes and flames of fire. In a narrow
defile they were met by a violent hurricane, which overthrew both the
mules and their riders, and urged them toward the precipices of the Val
del Bove. They sheltered themselves beneath some masses of lava, when
suddenly an earthquake shook the mountain, and their mules in terror
fled away. As day approached they returned on foot to Nicolosi,
fortunately without having sustained injury. In the course of the night
many bocche del fuoco (small lava vents) opened in that part of the Val
del Bove called the Bazo di Trifoglietto, a great fissure opened at the
base of the Giannicola Grande, and a crater was thrown up from which for
seventeen days showers of sand and scoriae were ejected.


EFFECT OF THE ERUPTION


During the next day a quantity of lava flowed down the Val del
Bove, branching off so that one stream advanced to the foot of Monte
Finocchio, and the other to Monte Calanna. Afterwards it flowed towards
Zaffarana, and devastated a large tract of wooded region. Four days
later a second crater was formed near the first, from which lava was
emitted, together with sand and scoriae, which caused cones to arise
around the craters. The lava moved but slowly, and towards the end of
August it came to a stand, only a quarter of a mile from Zaffarana.

On the second of September, Gemellaro ascended Monte Finocchio in the
Val del Bove in order to witness the outburst. He states that the hill
was violently agitated, like a ship at sea. The surface of the Val
del Bove appeared like a molten lake; scoriae were thrown up from the
craters to a great height, and loud explosions were heard at frequent
intervals. The eruption continued to increase in violence. On October
6 two new mouths opened in the Val del Bove, emitting lava which flowed
towards the valley of Calanna, and fell over the Salto della Giumenta,
a precipice nearly 200 feet deep. The noise which it produced was like
that of a clash of metallic masses. The eruption continued with abated
violence during the early months of 1853, and it did not finally cease
till May 27. The entire mass of lava ejected is estimated to have been
equal to an area six miles long by two miles broad, with an average
depth of about twelve feet.

This eruption was one of the grandest of all the known eruptions of
Etna. During its outflow more than 2,000,000,000 cubic feet of molten
lava was spread out over a space of three square miles. There have been
several eruptions since its date, but none of marked prominence, though
the mountain is rarely quiescent for any lengthened period.


THE LIPARI VOLCANOES


South-eastward of Ischia, between Calabria and Sicily, the Lipari
Islands arrest attention for the volcanic phenomena they present. On
one of these is Mount Vulcano, or Volcano, from which all this class of
mountains is named. At present the best known of the Lipari volcanoes
is Stromboli, which consists of a single mountain, having a very obtuse
conical form. It has on one side of it several small craters, of which
only one is at present in a state of activity.

The total height of the mountain is about 2000 feet, and the principal
crater is situated at about two-thirds of the height. Stromboli is one
of the most active volcanoes in the world. It is mentioned as being in
a state of activity by several writers before the Christian era, and the
commencement of its operations extends into the past beyond the limits
of tradition. Since history began its action has never wholly ceased,
although it may have varied in intensity from time to time.

It has been observed that the violence of its eruptive force has a
certain dependence on the weather--being always most intense when the
barometer is lowest. From the position of the crater, it is possible to
ascend the mountain and look down upon it from above. Even when viewed
in this manner, it presents a very striking appearance. While there is
an uninterrupted continuance of small explosions, there is a frequent
succession of more violent eruptions, at intervals varying in length
from seven to fifteen minutes.


HOFFMAN AT STROMBOLI


Several eminent observers have approached quite close to the crater,
and examined it narrowly. One of these was M. Hoffman, who visited it in
1828.

This eminent geologist, while having his legs held by his companions,
stretched his head over the precipice, and, looking right down into the
mouth of one of the vents of the crater immediately under him, watched
the play of liquid lava within it. Its surface resembled molten silver,
and was constantly rising and falling at regular intervals. A bubble of
white vapor rose and escaped, with a decrepitating noise, at each ascent
of the lava--tossing up red-hot fragments of scoria, which continued
dancing up and down with a sort of rhythmic play upon the surface.
At intervals of fifteen minutes or so, there was a pause in these
movements. Then followed a loud report, while the ground trembled, and
there rose to the surface of the lava an immense bubble of vapor. This,
bursting with a crackling noise, threw out to the height of about 1200
feet large quantities of red-hot stones and scoriae, which, describing
parabolic curves, fell in a fiery, shower all around. After another
brief repose, the more moderate action was resumed as before.

Lipari, a neighboring volcano, was formerly more active than Stromboli,
though for centuries past it has been in a state of complete quiescence.
The Island of Volcano lies south of Lipari. Its crater was active before
the Christian era, and still emits sulphurous and other vapors. At
present its main office is to serve as a sulphur mine. Thus the peak
which gives title to all fire-breathing mountains has become a servant
to man. So are the mighty fallen!



CHAPTER XXIII.

Skaptar Jokull and Hecla, the Great Icelandic Volcanoes.


The far-northern island of Iceland, on the verge of the frozen Arctic
realm, is one of the most volcanic countries in the world, whether we
regard the number of volcanoes concentrated in so small a space, or the
extraordinary violence of their eruptions. Of volcanic mountains there
are no less than twenty which have been active during historical times.
Skaptar in the north, and Hecla in the south, being much the best known.
In all, twenty-three eruptions are on record.

Iceland's volcanoes rival Mount Aetna in height and magnitude, their
action has been more continuous and intense, and the range of volcanic
products is far greater than in Sicily. The latter island, indeed, is
not one-tenth of volcanic origin, while the whole of Iceland is due
to the work of subterranean forces. It is entirely made up of volcanic
rocks, and has seemingly been built up during the ages from the depths
of the seas. It is reported, indeed, that a new island, the work
of volcanic forces, appeared opposite Mount Hecla in 1563; but this
statement is open to doubt.


VOLCANOES IN ICELAND


The eruptions of the volcanoes in Iceland have been amongst the most
terrible of those carefully recorded. The cold climate of the island
and the height of the mountains produce vast quantities of snow and ice,
which cover the volcanoes and fill up the cracks and valleys in their
sides. When, therefore, an eruption commences, the intense heat of the
boiling lava, and of the steam which rushes forth from the crater, makes
the whole mountain hot, and vast masses of ice, great fields of snow,
and deluges of water roll down the hill-sides into the plains. The lava
pours from the top and from cracks in the side of the mountain, or is
ejected hundreds of feet, to fall amongst the ice and snow; and the
great masses of red-hot stone cast forth, accompanied by cinders and
fine ashes, splash into the roaring torrent, which tears up rocks in its
course and devastates the surrounding country for miles.


DREADFUL FLOODS


An eruption of Kotlugja, in 1860, was accompanied by dreadful floods. It
began with a number of earthquakes, which shook the surrounding country.
Then a dark columnar cloud of vapor was seen to rise by day from the
mountain, and by night balls of fire (volcanic bombs) and red-hot
cinders to the height of 24,000 feet (nearly five miles), which were
seen at a distance of 180 miles. Deluges of water rushed from the
heights, bearing along whole fields of ice and rocky fragments of every
size, some vomited from the volcano, but in great part torn from the
flanks of the mountain itself and carried to the sea, there to add
considerably to the coastline after devastating the intervening country.
The fountain of volcanic bombs consisted of masses of lava, containing
gases which exploded and produced a loud sound, which was said to have
been heard at a distance of 100 miles. The size of the bombs, and the
height to which they must have reached, were very great. But the most
remarkable of the historical eruptions in Iceland were those of Skaptar
Jokull in 1783, and of Hecla in 1845. Of these an extended description
is worthy of being given.

Of these two memorable eruptions, that of Skaptar Jokull began on the
11th of June, 1783. It was preceded by a long series of earthquakes,
which had become exceedingly violent immediately before the eruption. On
the 8th, volcanic vapors were emitted from the summit of the mountain,
and on the 11th immense torrents of lava began to be poured forth from
numerous mouths. These torrents united to form a large stream, which,
flowing down into the river Skapta, not only dried it up, but completely
filled the vast gorge through which the river had held its course. This
gorge, 200 feet in breadth, and from 400 to 600 feet in depth, the lava
filled so entirely as to overflow to a considerable extent the fields
on either side. On issuing from this ravine, the lava flowed into a deep
lake which lay in the course of the river. Here it was arrested for a
while; but it ultimately filled the bed of the lake altogether--either
drying up its waters, or chasing them before it into the lower part of
the river's course. Still forced onward by the accumulation of molten
lava from behind, the stream resumed its advance, till it reached
some ancient volcanic rocks which were full of caverns. Into these it
entered, and where it could not eat its way by melting the old rock,
it forced a passage by shivering the solid mass and throwing its broken
fragments into the air to a height of 150 feet.


A TORRENT OF LAVA


On the 18th of June there opened above the first mouth a second of large
dimensions, whence poured another immense torrent of lava, which flowed
with great rapidity over the solidified surface of the first stream, and
ultimately combined with it to form a more formidable main current. When
this fresh stream reached the fiery lake, which had filled the lower
portion of the valley of the Skapta, a portion of it was forced up the
channel of that river towards the foot of the hill whence it takes its
rise. After pursuing its course for several days, the main body of this
stream reached the edge of a great waterfall called Stapafoss, which
plunged into a deep abyss. Displacing the water, the lava here leaped
over the precipice, and formed a great cataract of fire. After this, it
filled the channel of the river, though extending itself in breadth far
beyond it, and followed it until it reached the sea.