3. Dio History of Rome 66.21-23
In Campania some frightening and astonishing events occurred. A great fire suddenly flared up at the very end of the summer. Mt. Vesuvius, which stands near the sea below Naples, has in it inexhaustible fountains of fire. Once it had a symmetrical cone, and the fire leapt up from the center. The burning was confined to that area, and even now the outer parts of the mountain are untouched by fire. As a result, since the outer portions are not burned, while the center is continually growing brittle and turning to ash, the heights around the center are as high as ever, but the whole fiery portion of the mountain has been consumed over time, and has settled into a hollow. Thus the entire mountain resembles an amphitheater (if we may compare great things to small). Its heights support both trees and vines in abundance, but the crater is given over to the fire and sends up smoke by day and flame by night. In fact, it gives the impression that a great deal of all kinds of incense is being burned inside. This is the normal state of affairs, though with variations of degree. Often the mountain throws up ashes, as well, whenever there is extensive settling in the interior, and even discharges stones with a violent blast of air. It also rumbles and roars, as its vents are not obstructed but are open and free.
Such is Vesuvius, and these phenomena occur there year in year out. But all the occurrences that had taken place there in the past, however impressive, because unusual, they may have seemed to observers, nevertheless would be reckoned trivial in comparison with what now happened, even if they had all happened simultaneously. What happened was this.
Numbers of huge men appeared, but bigger than any human, more like the Giants in paintings. They were seen on the mountain, in the surrounding countryside, and in the cities, wandering over the earth day and night, and also journeying through the air. Then came a terrible dryness, and sudden violent earthquakes, so that the whole plain seethed and the heights leaped into the air. There were frequent rumblings, some underground, sounding like thunder, others on the surface, making a bellowing sound. The sea joined in the roar, and the sky added its peal. Then suddenly a dreadful crash was heard, as if mountains were collapsing in on themselves. First huge stones flew up as high as the mountain top, then came a great quantity of fire and endless smoke, so that the air was darkened and the sun entirely hidden, as if eclipsed. Thus day turned into night and darkness came out of the light. Some thought that the Giants were rising again in revolt (for many of their forms could still be discerned in the smoke, and a sound as of trumpets was heard), others believed that the whole universe was being resolved into chaos or fire. People fled, some from their houses into the streets, others from outside indoors, some from the sea to the land, others from the land to the sea. In their panic people regarded any place where they were not, as safer than where they were. All the while an inconceivable quantity of ash was being blown out; it covered both sea and land and filled all the air. Wherever it went it did a great deal of damage, especially to men and farms and sheep, and it destroyed all fish and bird life. Furthermore, it buried two entire cities, Herculaneum and Pompeii; in the latter the people were seated in the theater.
So much ash was there that some of it reached Africa and Syria and Egypt. It also appeared in Rome, filling the air overhead and darkening the sun. In Rome the fear lasted for many days, as people did not know what had happened and could not explain it. In fact, they too thought that the world was being turned upside down, that the sun was disappearing into the earth and the earth being lifted up into the sky. The ash did the Romans no great harm at the time, though later it brought them a terrible pestilence.