One effect of this first eruption of Vesuvius was to break down the western wall of the crater and destroy the entire side of the mountain next the sea, leaving as the only remains of the ancient crater a little ridge on the south flank, and that portion, which under the name of Somma, still encircles the present cone.
From the time of its first eruption, the restlessness of Vesuvius has been well observed. The next action occurred in the year 203. In the meantime the sides of the crater had become overgrown with brushwood and forest trees, and the basin itself was a favorite haunt of wild boars. In the year 472 the mountain broke forth with more violence than at either of the former periods. The roaring was simply indescribable. The clouds of ashes spread over the entire adjacent region. Houses toppled down miles away. Scores of people were suffocated. The ashes fell in showers at Constantinople and Tripoli.
Other eruptions followed in 512, 685, and 993. No stream of molten lava issued at any of these. But in 1036, a great eruption took place, during which, we are told, the lava poured forth from fissures in the sides, as well as from the top, and ran in a broad and deep stream into the sea. Thirteen years later another similar outbreak occurred; then ninety years passed without any disturbance.
Of these eruptions, little beyond the bare fact is known. But from the time of the last one referred to, 1139, scientific men have carefully watched each outbreak. In 1198, the neighboring crater of Solfatara Lake was in eruption; in 1302, Ischia, dormant over fourteen hundred years, exhibited wonderful activity. For more than a year earthquakes shook the island, and at length there burst forth a lava stream from the southeast side of the mountain, flowing two miles, to the sea. Many houses were destroyed during the two months’ eruption; and not a few of the inhabitants abandoned the island. But Vesuvius was quiet till 1306. Again it broke forth in 1500. During this time Ætna was in a state of unwonted activity.
The eruption of 1538 broke forth at the foot of the mountain, and was marked by some peculiar features. The plain between Avernus, Monte Barbaro, and the sea, was first raised a little, and many cracks made in it, from some of which water issued. The sea retreated about two hundred paces, leaving many fish on the sands at the disposal of the people of Pozzuoli, a little watering place on the Bay of Baiæ. On the evening of September 29, numerous shocks of earthquake occurred, and about two o’clock in the night an immense fissure opened near the lake and extended toward the town. Smoke, fire, stones, and mud made of ashes, were vomited furiously, the whole process being attended by a terrible roaring, as of continual loudest thunder. Stones and masses of pumice larger than an ox were thrown out. The gulf in the town widened, and not a few houses were broken to pieces, or swallowed up in the chasm.