eruptions, of which the AD 79 one was the most recent. The calderas are aligned in a roughly east-west direction, and all contributed to forming present-day's Somma caldera. The eruptions are named after the tephra deposits produced by them, which in turn are named after the place where the deposits were first identified: 18,300 years ago: the Basal Pumice (Pomici di Base) eruption, VEI 6, the original formation of the Somma caldera. The caldera's formation was asymmetric towards the west. The eruption was followed by a period of much less violent, lava-producing eruptions. 16,000 years ago: the Green Pumice (Pomici Verdoline) eruption, VEI 5. Around 11,000 years ago: the Lagno Amendolare eruption, smaller than the Mercato eruption. 8,000 years ago: the Mercato eruption (Pomici di Mercato) – also known as Pomici Gemelle or Pomici Ottaviano, VEI 6. Around 5,000 years ago: two explosive eruptions smaller than the Avellino eruption. 3,800 years ago (19th century BC): the Avellino eruption (Pomici di Avellino), VEI 6; its vent was apparently west of the current crater and the eruption destroyed several Bronze Age settlements of the Apennine culture, including ancient Afragola. Several carbon dates on wood and bones offer a range of possible dates of about 500 years in the mid-2nd millennium BC. In May 2001, near Nola, Italian archaeologists using the technique of filling every cavity with plaster or substitute compound, recovered some remarkably well-preserved forms of perishable objects, such as fence rails, a bucket and especially in the vicinity, thousands of human footprints pointing into the Apennines to the north. The settlement had huts, pots and goats. The residents had hastily abandoned the village, leaving it to be buried under pumice and ash in much the same way that Pompeii and Herculaneum were later preserved. Pyroclastic surge deposits were distributed to the northwest of the vent, travelling as far as from it, and lie up to deep in the area now occupied by Naples. The volcano then entered a stage of more frequent, but less violent eruptions, until the most recent Plinian eruption, which destroyed Pompeii and Herculaneum. Evidence of these eruptions comes from badly preserved ashfall deposits that have been dubitatively assigned to Either the Somma-Vesuvius complex, or the Phlegrean fields. The last of these may have been in 217 BC. There were earthquakes in Italy during that year and the sun was reported as being dimmed by gray haze or