Such was the scene by day—awful, melancholy, dismal—but at night it assumed a character of indescribable sublimity. The large cauldron, in place of its bloody glare, now glowed with intense brilliancy, and the surface sparkled with shifting points of dazzling light, occasioned by the jets in constant play. The broad canopy of clouds above the pit, which seemed to rest on a column of wreaths and curling heaps of lighted vapour, and the amphitheatre of rocks around the lower depths, were brightly illuminated from the boiling lavas, while a lurid red tinged the distant parts of the inclosing walls and threw their cavernous recesses into deeper shades of darkness. Over this scene of restless fires and fiery vapours, the heavens by contrast seemed unnaturally black, with only here and there a star, like a dim point of light.
A paroxysmal eruption is generally announced by the intensification of the phenomena above described. Slight earthquakes are felt in the neighbourhood of the volcano, and follow each other in more rapid succession and with greater violence as the catastrophe draws near. A deep noise like the rolling of thunder, or like the roar of distant artillery, is heard under the ground; the white steam from the crater ascends in denser clouds, which soon acquire a darker tinge; and now the bottom of the crater suddenly bursts with a terrific crash, and with the rapidity of lightning, an immense column of black smoke shoots up into the air, and, expanding at its upper end into a broad horizontal canopy, assumes a shape which has been compared with that of the Italian pine, the graceful tree of the South. As the column of smoke spreads over the sky, it obscures the light of the sun and changes day into night. Along with the smoke, showers of glowing lava are cast high up into the air, and, rising like rockets, either fall back into the crater or rattle down the declivity of the cone.
At night the scene assumes a character of matchless grandeur, when the column of smoke—or, more properly speaking, of scoriæ, vapour, and impalpable dust—is illuminated by the vivid light of the lava glowing in the crater beneath. It then appears as an immense pillar of fire, rising with steady majesty in the midst of the uproar of all the elements, and ever and anon traversed by flashes of still greater brilliancy from the masses of liquid lava hurled forth by the volcano.
The detonations which accompany an eruption are sometimes heard as single crashes, at others as a rolling thunder or as a continuous roaring. They are frequently audible at an astonishing distance, over areas of many thousand square miles, and with such violence that they may be supposed to proceed from the immediate neighbourhood. Thus, during the eruption of Cosiguina in Nicaragua, which took place in the year 1834, the detonations were heard as loud as a thunderstorm in the neighbourhood of Kingston in Jamaica, and even at Santa Fé de Bogota, which is a thousand miles distant from the volcano. With the increase of steam generated during an eruption, the quantity of ejected scoriæ likewise increases in an astonishing manner, so that the volcano’s mouth resembles a constantly discharging mine of the most gigantic dimensions.
The stones and ashes projected during a volcanic eruption vary considerably in size, from blocks twelve or fifteen feet in diameter to the finest dust. Both their immense quantity, and the force with which they are hurled into the air, show the utter insignificance of the strength displayed by the most formidable engines invented by man when compared with elementary power. Huge blocks are shot forth, as from the cannon’s mouth, to a perpendicular elevation of 6,000 feet, and La Condamine relates that in 1533 Cotopaxi hurled stones of eight feet in diameter in an oblique direction to the distance of seven miles. The lighter scoriæ, carried far away by the winds, not seldom bury whole provinces under a deluge of sand and ashes; and their disastrous effects, spreading over an immense area, are frequently greater than those of the lava-streams, whose destructive power is necessarily confined to a narrower space. To cite but a few examples, the rain of sand and ashes which in 1812 menaced the Island of St. Vincent with the fate of Pompeii soon buried every trace of vegetation, and the affrighted planters and negroes fled to the town. But here also the black sand, along with many larger stones, fell rattling like hail upon the roofs of the houses, while at the same time a tremendous subterranean thunder increased the horrors of the scene. Even Barbadoes, though eighty miles from St. Vincent’s, was covered with ashes. A black cloud, approaching from the sea, brought with it such pitchy darkness that in the rooms it was impossible to distinguish the windows, and a white pocket-handkerchief could not be seen at a distance of five inches.
The fall of ashes caused in April 1815 by the eruption of the Temboro, in Sumbawa, not only devastated the greater part of the island, but extended in a westerly direction to Java, and to the north, as far as Celebes, with such an intensity that it became perfectly dark at noon. The roofs of houses at the distance of forty miles were broken in by the weight of the ashes that fell upon them. To the west of Sumatra the surface of the sea was covered two feet deep with a layer of floating pumice or scoriæ, through which ships with difficulty forced their way.
By the terrific eruption of Cosiguina in the Gulf of Fonseca, in Central America, in 1835, all the ground within a radius of twenty-five miles was loaded with scoriæ and ashes to the depth of ten feet and upwards, while the lightest and finest ash was carried by the winds to places more than 700 miles distant. Eight leagues to the southward of the crater the ashes covered the ground to the depth of three yards and a half, destroying the woods and dwellings. Thousands of cattle perished, their bodies being in many instances one mass of scorched flesh. Deer and other wild animals sought the towns for protection; birds and beasts were found suffocated in the ashes, and the neighbouring streams were strewed with dead fish.
When we consider the amazing quantity of stones and ashes ejected in these and similar instances by volcanic power, we cannot wonder that considerable mountains have frequently been piled up by one single eruption. Thus in the Bay of Baiæ near Naples, Monte Nuovo, a hill 440 feet high, and with a base of more than a mile and a half in circumference, formed, in less than twelve hours, on September 29, 1538; and a few days gave birth to Monte Minardo, near Bronte, on the slopes of Etna, which rises to the still more considerable height of 700 feet. It would be curious to calculate how many thousands of workmen, and what length of time, man would need to raise mounds like these, produced by an almost instantaneous effort of nature.
In other cases the expansive power of the elastic vapours, which cast up these prodigious masses from the bowels of the earth, is such as to blow to pieces the volcanic cone through which it seeks its vent.
In Quito there is an ancient tradition that Capac Urcu, which means ‘the chief,’ was once the highest volcano near the equator, being higher than Chimborazo, but at the beginning of the fifteenth century a prodigious eruption took place which broke it down. The fragments of trachyte, says Mr. Boussingault, which once formed the conical summit of this celebrated mountain, are at this day spread over the plain. On August 11, 1772, the Pepandajan, in Java, formerly one of the highest mountains of the island, broke out in eruption; the inhabitants of the country around prepared for flight, but, before they could escape, the greater part of its summit was shivered to pieces and covered the neighbourhood with its ruins, so that in the upper part of the Gurat valley forty villages were completely buried. During the dreadful eruption of 1815, the Temboro, in Sumbawa, is said to have lost at least one-third of its height from the explosion of its summit, and similar instances are mentioned as having occurred among the volcanoes of Japan.