During the eruption the
uncle of Pliny the Younger (Pliny the Elder), admiral of the roman fleet based
in Misenum, went to the rescue of the people endangered by the eruption and lost
his life. We have no information on the state of Vesuvius immediately after
the eruption of 79. The first account of continuing activity is from Galenus
(c.172 AD) who testifies that "the matter in it (Vesuvius) is still burning". Dio Cassius in 203 AD reports a violent eruption heard in
Capua, some 40
km from the volcano. Two large eruptions occurred in 472 and 512. Marcellinus
Comes reported that, on the 6th of November, 472, "Vesuvius (...) erupted
the burning interiors, caused night during the day and covered all Europe with
fine ash". Information about the eruption of 512 is more detailed.
Cassiodorus,an officer of king Teodoricus, wrote a letter to ask the exemption
of taxes for the people affected by the eruption; in his letter he reports that
"a burnt ash flies in the sky, and, forming ashy clouds, it rains with ash
droplets also in the provinces beyond the sea (...). It is possible to see ash
rivers flowing like liquid, bringing hot sands and (....) the fields grow
suddenly up (the fields are covered with sand) to the top of the trees (.....)
and are ravished by the sudden heat". Several other eruptions are reported
in 685 (Paulus Diaconus), 787 and 968.
In 968, Leo Marsicanus reports in a
chronicle of the
Cassino Monastery that "Mount Vesuvius exploded with
flames and emitted a great amount of gluey and sulphurous matter that formed a
river hurriedly flowing to the sea" . Several authors report other
eruptions in 991, 993 and 999 (see in Alfano, 1924) but they must be regarded as
suspicious because of the belief of the end of the world in 1000 AD.
Leo Marsicanus refers of another eruption on the 27 of January, 1037, that lasted
for six days. The chronicle of the Cassino monastery records an explosive
eruption between 1068 and 1078. The last eruption before a long quiescent period
occurred on the 1st of June, 1139. Several sources refer to it as a strong
explosive eruption (Falcone Beneventano, the Chronicle of the Monastery of Cava
dei Tirreni, John of Salisbury). It lasted eight days and ashes covered Salerno,
Benevento, Capua and Naples. No reliable report of volcanic activity is
available until 1500, when Ambrogio di Nola reports a small explosion. From 1500
until to 1631, no eruption occurred on Vesuvius. Records are good during this
period, and none mention volcanic activity.
The activity between 1631 and 1944
The great eruption of 1631 is the largest explosive eruption of
Mt. Vesuvius since those of 472 and 512 AD. It occurred after 131 years of quiescence. Large trees covered the Gran Cono, the cone within the Somma Caldera, and local people did not remember it being a volcano. The mountain was called "La Montagna di Somma" (the Mountain of Somma, a small town on its northern side). Several months before the beginning of the eruption, people near the volcano felt some earthquakes (Braccini, 1632). They were not particularly scared because earthquakes from the nearby Apennine chain were often felt in the area (a large one had occurred three years before in Apulia, in 1628). The seismic activity became more severe in the few days before the eruption. Nevertheless, the awakening of Vesuvius in 1631 surprised the inhabitants. A strong explosive eruption started in the night between 15 and 16 December of 1631 and its paroxysmal stage lasted two days. Between the great eruption of 1631 and 1944 Vesuvius, is almost always in activity with only brief periods of quiescence not exceeding 7 years. Major eruptions occurred in 1794, 1822, 1834, 1850 e 1872. After 1872 slow lava effusions, lasting several years formed small lava accumulation (lava domes) in the proximity of the crater. One of this, named Colle Umberto, formed between1895 and 1899 in the area between the cone and the Observatory. In 1872, after the eruption, Vesuvius cone had its maximum elevation at 1335 m a.s.l.. In May, 1905, a new eruption began, firstly with slow lava effusions and, since January, 1906, with intermittent explosive activity (strombolian activity). On the 7th of April, 1906 the eruption reached the climax with lava fountains and earthquakes. The eruptive column of ash and gas reached the height of 13000 m. The eruption ends in the last days of April.
During the eruption of 1906 the top of Vesuvius was truncated and formed a vast crater with a diameter of approximately 500 m and a depth
of 250 m. The crater rim was lowered to 1145 m asl at its minimum height. After the eruption there was short period of quiescence followed by a prolonged period of permanent activity since 5 July of 1913. This activity , caracterized by quiet effusion of lava and minor explosion from a small conelet, slowly filled the 80 million m3 crater left by the eruption of 1906. By 28 November of 1926 the crater had been filled up to its lower edge (~1070 m) and from that time on, small lava flows descended along the slopes of the crater. In June 1929 a major lava flow extended outside the Somma caldera rim and reached the village of Terzigno on the eastern slope of the volcano. The lava flow emission was followed by a phase of lava fountaining accompanied by sustained seismic tremor. By 1944 the lava field had almost filled up all the extension of the crater up to the altitude of about 1140-1150 m asl. Only a few remains of the original crater were visible especially on the south-western rim , where was located the highest point of the crater at 1186 m asl. The conelet, built at the center the lava field, had reached an height of ~1260 m asl. On 6 January, 1944 there was an lava flow from the conelet that rapidly reaches the border of the rim and outflows. The small lava flows continues until 26 January outside the rim and until 23 February within it. On that day the activity ends. The eruption of
Mt. Vesuvius of March 1944, is the last eruption occurred at Vesuvius. Since then the volcano has been in a quiescent stage without any major sign of activity.