THE ENVIRONMENTAL AND GEOMORPHOLOGICAL CONTEXT OF THE VOLCANO
The region surrounding an active volcano is subject to very rapid changes ingeomorphology and environmental conditions. A new cone can be built up in a matter of months or a few years during periods of frequent lava flow eruptions, only to be destroyed by a violent Plinian explosive eruption and caldera collapse after centuries of dormancy. This intermittent pattern of activity is characteristic of the evolution of Vesuvius volcano, which suddenly terminated a long dormant period with catastrophic consequences in AD 79. This chapter reviews the volcanic history of Vesuvius, and presents a reconstruction of the AD 79 eruption, based on modern volcanological studies of the deposits in Pompeii, Herculaneum and numerous other sites in Campania, where the so-called “Pompeii pumice” is exposed at the surface. The effects of the eruption were truly prodigious. In addition to the death of thousands of inhabitants and total loss of two important Roman cities, the landscape of Campania was totally transformed. A deposit ranging in thickness from a meter to tens of meters was laid over all the farms and agricultural lands surrounding Vesuvius, and the advance of pyroclastic flows into the Bay of Naples pushed out the coastline several hundred meters and obliterated all ports south of Naples.