Ferdinand II of
Bourbon, king of the Two Sicilie from 1830 to 1859, on september 3 1841
gave start to the construction of the Meteorological Vesuviano Observatory , the
first volcanologic observatory of the world. The solemn building was inaugurated
on september 28 1845 and delivered to the director, the famous
physicist Macedonio Melloni, in March 1848. For beyond 150 years the presence of the
Observatory has allowed the meticulous observation of the eruptions and
their premonitory ones, the systematic collection of the products emitted from
the volcano, the planning and the experimentation of new scientific instruments,
so this work made the Vesuvio the volcano best known and better
studied in the world.
The Vesuviano Observatory manages local sismic networks, among those the
Vesuvio, the Flegrei Fields and Ischia, with the scope to watch the Neapolitan
volcanic areas.
The seismic permanent network of the Vesuvio is constituted of ten stations of
survey, nine of which are distributed on the volcano and one is in Nola,
at, approximately, 15 kilometers from the crater.
A digital mobile network , moreover, allows to increase the density of stations
in the central part of the network, in order to improve the precision of
localization of earthquakes and the analysis of the focal mechanisms.
we thank for the kind collaboration, the
great availability and the love for her "Mountain " the lady doctor
Adriana Nave
The volcanic
activity in the vesuvian area is begun, approximately, 300.000 years ago and has
formed in the time the volcanic complex of Somma-Vesuvio, constituted from two
buildings: the Mount Somma and the most recent Vesuvio. The Somma grew for
accumulates of lavic taps and for placed of explosive eruptions of low
energy. The apex of the building, that it could have caught up a height of
approximately 2.000 m., sank after one violent explosive eruption of pliniano
type, approximately 18.000 years ago. As a result of this event was created a
caldera to the top whose shape was modified repeatedly during the successive
pliniane eruptions. In the caldera of the Mount Somma then the Vesuvio has
grown.
Before the 79 A.D., the activity of Somma-Vesuvio has been characterized from 4
eruptions of great energy (pliniane), preceded from periods of rest of several
hundreds of years and from explosive eruptions of little inferior energy
(subpliniane), preceded from periods of rest of some century. After the 79 A.D.,
the Vesuvio has seen the succeeding of frequent eruptions (explosive,
effusive and mixed) and moment of rest also much long, interrupted by
violent explosive eruptions like that subpliniana of the 472. The last
subpliniana eruption, happened in 1631, has been preceded from a period of
lasted rest nearly five centuries.
After 1631 and until 1944, the Vesuvio has been characterized from frequent
eruptions not great energy, but often of remarkable spectacular effect.
The history of the Vesuvio, reconstructed arranging the deducted information
from historical reports and documents with the results of the studies of the
products of the several eruptions, show that the volcano has been characterized
from the alternation between periods of intense activity, in which the culvert
it is open, and long periods to obstructed culvert. During the periods of rest
the magmatic tank is fed from the deep one, changes the chemical composition of
the magma and increases upgrades them explosive. A period of rest is interrupted
from an explosive eruption, as well as more violent the how much longest
has been the rest. This eruption leaves the times the opened culvert, giving to
beginning to a period of activity with frequent eruptions of weak energy.
The last phase of activity lasted three centuries and it has been concluded with
the eruption of the ' 44, that it has marked the beginning of a period of rest,
whose duration is impossible to preview. During this period the volcano has
given only modest signs of life which activities of fumaroles,
mostly to the inside of the crater, and earthquakes of low energy. Its history
indicates that the volcano cannot be considered extinguished and is highly
probable that the quiescence puts into effect them comes sooner or later
interrupted from one new, violent, eruption.
The eruption began on 24 August of the 79 A.D. towards noon. The
first eruptive phase was characterized from strong "freatomagmatiche"
outbreaks. After this phase, magmatic outbreaks were followed until the morning
of the following day, feeding a column constituted mostly from gas, pomici and
ashes that were raised until 30 kilometers. The high part of the column
expanded, assuming the shape of a pine, and was pushed from the twenty towards
south-east. The contained particles in it often fell to the ground, forming a
layer of pomici that to Pompei and Oplonti caught up 2-3 m. of thickness.
Partial collapses of the eruptive column generated piroclastic flows that
noticed to high long speed the flanks of the volcano, caught up and destroyed
Ercolano. The city of Pompei, the much farthest one, did not come caught up and
the greater part of its inhabitants survived. During the last hours of the night
the intensity of the eruptive activity diminished.
At the first hours in the 25 morning, a "freatomagmatica" outbreak
generated piroclastici, turbulent flows - terrible "the base-surge " - that,
travelling at the speed of a hurricane, came down along the slopes of the
volcano, devastated the surrounding areas until distances of 15 kilometers and
caused numerous victims also between the inhabitants of Pompei that were
survivors to the first phase of the eruption. In the course of the day the
outbreaks diminished of intensity and, in evening stopped of all, leaving one
large pall of ashes and pomici on the huge area. The abundant rains, provoked
also from the breaking in in the atmosphere of enormous fine particle and vapor
amounts, mobilized this material, forming dense mud taps that came down from the
flanks of the volcano and of the Appennine relieves along it goes them to them,
ulteriorly having the territory of the vesuvian area.
The eruption of
1631 has been most violent and destructive of the history of the Vesuvio in the
last millenium. After along period of quiescence, approximately 5 centuries,
preceded from one series of premonitory phenomena, which earthquakes and
raisings of the ground, the volcano waked causing the death of approximately
6.000 persons and the devastation of an area nearly 500 km. 2 The eruption began at the 7 in the morning of 16 December, with the
formation of an eruptive column of approximately 15 km., from which they began
to fall pomici and ashes in the area to east of the Vesuvio. At the 10 in the
morning of 17 December, from the central crater generated piroclastici
flows, gas clouds loaded with magma fragments that, sliding to long high
velocity the flanks western and southern of the volcano, they destroyed all that
they met in their way. In the night between the 16 and the 17, and in the
afternoon of the 17, the abundant rains mobilized the incoherent ash cover
causing the formation of mud taps. The taps came down from the flanks of
the volcano, from the slopes of the Appennine to north and the
northeast.
The phase of paroxysm in the eruption lasted three days, provoking an
enormous panic between the population. There were on the roads of Naples public
confessions of sins, accompanied from extraordinary manifestations of penance,
and were organized processions with the statue and the blood of S. Gennaro, so
that the patron appease that divine temper of which the outbreak of the Vesuvio
it seemed the indubitabile sign.
The Count of Monterrey, viceroy of Naples from January of that year, sent
some ships to collect the survivors of Torre del Greco and Torre Annunziata.
After some months, deeply upsetting from the event, it made to affix in Portici
a tablet that it exhorts the descendants not to forget the nature about
the mountain, and to recognize ready the premonitory ones of a volcanic
eruption.
On 18 March of 1944, during the occupation of the allied troops,
began the last eruption of the Vesuvio, that concluded a period of activity
begun in 1914, during which it had been taken place the only modest eruptions
from the central crater .
Between 1914 and 1944, lave and the slag produced from the volcano had filled up
crater, wide 720 m. and deep 600 m., than it had been formed during the previous
eruption of 1906.
A little cone of slag it emerged from the crater.
13-17 March
The little cone of slag it begins to collapse and the sismic activity becomes
more intense. A new slag cone born and collapsed again.
18 March
The eruption begins in the afternoon with slag launch. At the 16,30 a lavic
strained overflowed from the northern part of the crater and catches up the
Valle dell'Inferno at the 22.30. Nearly at the same time an other tap overflows
from the southern part of the crater. At the 23 there was also a spillage
of washes from the western part of the crater: the tap follows the railroad of
the funicular and interrupts the railroad.
19 March
At the 11 the washes flows along the Fosso della Vetrana.
20 March
Between the afternoon and the night, new strained overflowed from the northern
part of the crater. All the effusive activities are accompanied by sismic tremor
with increasing amplitude until half of the day.
21 March
The southern tap arrests at a quota approximately 300 m. on the sea level. In
the night, the northern tap catches up S. Sebastiano and Massa di Somma and is
divided in two coppers that are left over in direction of Cercola, from which in
evening they are distant approximately 1,5 km. S. Sebastiano and Massa di Somma
come evacuate and the 10,000 inhabitants transferred to Portici. Around
the 17, the spectacular fountains of wash begin to form, the last of which hard
approximately 5 hours and catch up a height nearly 1,000 m. Fragments of wash
and ashes moved from the winds in quota, are deposited on the Southeastern
areas of the volcano, between Angri and Pagani. The smaller fragments catch up
distances than beyond 200 km. towards south-east. Slag until a kilogram of
weight catch up the city of Poggiomarino, at approximately 11 km. from the
crater. Great still warm slag amounts are accumulated on the flanks of the Great
Cone. The sismic tremor continues, with maximums of amplitude in coincidence
with the emission of the fountains of wash.
22 March
Towards the 1 p.m. the eruption was in its maximum activity. A column of
gas and ash rises at a 6 Km. of height. Ashes and slag fall on the
south-eastern slope of the volcano. A big seismic tremor accompanies all the
phase, during which the crater becomes wide.
23 March
A series of explosions are caused by the entrance of water in the volcanic duct
and there was a swarm of earthquakes.
29 March
The eruption end. It caused the death of some persons, the collapse
of the roofs and serious damages in S. Sebastiano and Massa di Somma.
For beyond 150 years the presence of the
Observatory has allowed the meticulous observation of the eruptions and
their premonitory ones, the systematic collection of the products emitted from
the volcano, the planning and the experimentation of new scientific instruments,
so this work made the Vesuvio the volcano best known and better
studied in the world.
The eruption began on 24 August of the 79 A.D. towards noon. The
first eruptive phase was characterized from strong "freatomagmatiche"
outbreaks. After this phase, magmatic outbreaks were followed until the morning
of the following day, feeding a column constituted mostly from gas, pomici and
ashes that were raised until 30 kilometers. The high part of the column
expanded, assuming the shape of a pine, and was pushed from the twenty towards
south-east. The contained particles in it often fell to the ground, forming a
layer of pomici that to Pompei and Oplonti caught up 2-3 m. of thickness.
Partial collapses of the eruptive column generated piroclastic flows that
noticed to high long speed the flanks of the volcano, caught up and destroyed
Ercolano. The city of Pompei, the much farthest one, did not come caught up and
the greater part of its inhabitants survived. During the last hours of the night
the intensity of the eruptive activity diminished.
On 18 March of 1944, during the occupation of the allied troops,
began the last eruption of the Vesuvio, that concluded a period of activity
begun in 1914, during which it had been taken place the only modest eruptions
from the central crater .