It will be seen from the account of the foregoing eruptions that 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 scoriæ are discharged, the action localises 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 breaching 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 in the course of a few days it only moves a few yards in 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.
Of the seventy-eight eruptions described above, it will be noticed that not more than nineteen have been of extreme violence, while the majority have been of a slight and comparatively harmless character.
FOOTNOTES:
[18] Translated by L. E. Upcott, m.a.
[19] "A true and exact relation of the late prodigious earthquake and eruption of Mount Ætna or Monte Gibello; as it came in a letter written to his Majesty from Naples by the Rt. Honble. the Earl of Winchelsea late Ambassadour at Constantinople, who in his return from thence visiting Catania in the Island of Sicily, was an eye-witness of that dreadful spectacle." Published by Authority. Printed by T. Newcomb in the Savoy. 1669.