Vesuvius

Vesuvius (also Vesevus in ancient poets), a volcano rising from the eastern margin of the Bay of Naples in Italy, about 7 m. E.S.E. of Naples, in the midst of a region which has been densely populated by a civilized community for more than twenty-five centuries. Hence the mountain has served as a type for the general popular conception of a volcano, and its history has supplied a large part of the information on which geological theories of volcanic action have been based. The height of the mountain varies from time to time within limits of several hundred feet, according to the effects of successive eruptions, but averages about 4000 ft. above sea-level (in June 1900, 4275 ft., but after the eruption of 1906 considerably less). Vesuvius consists of two distinct portions. On the northern side a lofty semicircular cliff, reaching a height of 3714 ft., half encircles the present active cone, and descends in long slopes towards the plains below. This precipice, known as Monte Somma, forms the wall of an ancient prehistoric crater of vastly greater size than that of the present volcano. The continuation of the same wall round its southern half has been in great measure obliterated by the operations of the modern vent, which has built a younger cone upon it, and is gradually filling up the hollow of the prehistoric crater. At the time of its greatest dimensions the volcano was perhaps twice as high as it is now. By a colossal eruption, of which no historical record remains, the upper half of the cone was blown away. It was around this truncated cone that the early Greek settlers founded their little colonies.

At the beginning of the Christian era, and for many previous centuries, no eruption had been known to take place from the mountain, and the volcanic nature of the locality was perhaps not even suspected by the inhabitants who planted their vineyards along its fertile slopes, and built their numerous villages and towns around its base. The geographer Strabo, however, detected the probable volcanic origin of the cone and drew attention to its cindery and evidently fire-eaten rocks. From his account and other references in classical authors we gather that in the first century of the Christian era, and probably for hundreds of years before that time, the sides of the mountain were richly cultivated, as they are still, the vineyards being of extraordinary fertility. The wine they produce is known as Lacrimae Christi. But towards the top the upward growth of vegetation had not concealed the loose ashes which still remained as evidence of the volcanic nature of the place. On this barren summit lay a wide flat depression, surrounded with rugged walls of rock, which were festooned with wild vines. The present crater-wall of Monte Somma is doubtless a relic of that time. It was in this lofty rock-girt hollow that the gladiator Spartacus was besieged by the praetor Claudius Pulcher; he escaped by twisting ropes of vine branches and descending through unguarded fissures in the crater-rim. A painting found in Pompeii in 1879 represents Vesuvius before the eruption (Notizie degli scan, 1880, pi. vii.).

After centuries of quiescence the volcanic energy began again o manifest itself in a succession of earthquakes, which spread ci larm through Campania. For some sixteen years after 63 t]

hese convulsions continued, doing much damage to the sur- 0:

Dunding towns. At Pompeii, for example, among other de- a astation, the temple of Isis was~ shaken into ruins, and, as an ii iscription records, it was rebuilt from the foundations by the d sunificence of a private citizen. On the 24th of August 79 ri he earthquakes, which had been growing more violent, culmi- 11

ated in a tremendous explosion of Vesuvius. A contemporary t ccount of this event has been preserved in two letters of the tl ounger Pliny to the historian Tacitus. He was staying at ~

lisenum with his uncle, the elder Pliny, who was in command d f the fleet. The latter set out on the afternoon of the 24th to lc ttempt to rescue people at Herculaneum, but came too late, and rent to Stabiae, where he spent the night, and died the following h ~orning, suffocated by the poisonous fumes which were ex- A

aled from the earth. This eruption was attended with great it estruction of life and property. Three towns are known to d ave been destroyedHerculaneum at the western base of the y olcano, Pompeii on the south-east side, and Stabiae, still farther sl outh, on the site of the modern Castellamare. There is no evi- 0

ence that any lava was emitted during this eruption. But the bundant steam given off by the volcano seems to have con- c ensed into copious rain, which, mixing with the light volcanic V

ust and ash, gave rise to torrents of pasty mud, that flowed p own the slopes and overwhelmed houses and villages. Hercu- a ineum is believed to have been destroyed by these water h was, and there is reason to suppose that similar materials a lied the cellars and lower parts of Pompeii. Comparing the si tatements of Pliny with the facts still observable in the district, 0

re perceive that this first recorded eruption of Vesuvius belongs a o that phase of volcanic action known as the paroxysmal, when, c fter a longer or shorter period of comparative tranquillity, a U

olcano rapidly resumes its energy and the partially filled-up ti rater is cleared out by a succession of tremendous explosions. b For nearly fifteen hundred years after the catastrophe of 79 t, Tesuvius remained in a condition of less activity. Occasional g ruptions are mentioned, e.g. in AD. 203, 472 and 685, and nine in c he middle ages down to 1500. None, however, was of equal im- b ortance with the first, and their details are given vaguely by t.

he authors who allude to them. By the end of the 15th century n he mountain had resumed much the same general aspect as it is resented before the eruption described by Pliny. Its crater- n rails, some 5 m. in circumference, were hung with trees and o rushwood, and at their base stretched a wide grassy plain, where attic grazed and the wild boar lurked in the thickets. The ri entral tract was a lower plain, covered with loose ashes and e riarked by a few pools of hot and saline water. At length, 0

,fter a series of earthquakes lasting for six months and gradu- ~

ily increasing in violence, the volcano burst into renewed ~

aroxysmal activity on the 16th of December 1631. Vast p PRINTED If ouds of dust and stones, blown out of the crater and funnel of ie volcano, were hurled into the air and carried for hundreds miles, the finer particles falling to the earth even. in the Adriic and at Constantinople. The clouds of steam condensed to copious torrents, which, mingling with the fine ashes, proiced muddy streams that swept far and wide over the plains, aching even to the foot of the Apennines. Issuing from the tnks of the mountain, several streams of lava flowed down wards the west and south, and reached the sea at twelve or iirteen different points. Though the inhabitants bad been arned by the earlier convulsions of the mountain, so swiftly d destruction come upon them that 18,ooo are said to have St their lives.

Since this great convulsion, which emptied the crater, Vesuvius is never again relapsed into a condition of total quiescence. t intervals, varying from a few weeks or months to a few years, has broken out into eruption, sometimes emitting only steam, ist and scoriae, but frequently also streams of lava. The lars 176667, 1779, 1794, 1822, 1872 and 1906 were marked by ecial activity. The last completely altered the aspect of the me, considerably reducing its height.

The modern cone of the mountain has been built up by suc~ssive discharges of lava and fragmentary materials round a Int of eruption, which lies a little south of the centre of the Tehistoric crater. The southern segment of the ancient cone, iswering to the semicircular wall of Somma on the north side, is been almost concealed, but is still traceable among the younger ~cumulations. The numerous deep ravines which indented the des of the prehistoric volcano, and still form a marked feature I the outer slopes of Somma, have on the south side served channels to guide the currents of lava from the younger)ne. But they are gradually being filled up there and will Ltimately disappear under the sheets of molten rock that from me to time rush into them from above. On one of the ridges Itween these radiating valleys an observatory for watching ie progress of the volcano was established by the Neapolitan)vernment, and is still supported as a national institution. A)ntinuous record of each phase in the volcanic changes has len taken, and some progress has been made in the study of te phenomena of Vesuvius; and in prognosticating the occurnce and probable intensity of eruptions. The foot of the tone reached from Naples by electric railway, and thence a wirepc railway (opened in 1880) carries visitors to within I5o yds. the mouth of the crater.

See John Phillips, Vesuvius (1869); Pompei e in Regione Sollerta dal Vesuvio nell Anno 79 (Naples, 1879); L. Palmieri, Vesuvio ~a sun Storia (Milan, 1880); H. J. Johnstone-Lavis, The Geology Monte Somma and Vesuvius (1884), in Quart. Journ. Geol. ~c. vol. xl. p. 85; J. L. Lobley, Mount Vesuvius (London, 1889); Furchheim, Bibliografia del Vesuv-io (Naples, 1897); T.- McK. ughes, Herculaneurn, in Proc. Camb. Antig. Soc. No. xlviii- 25 (Cambridge, 1908). (A. GE.; P. As.)