Mount Vesuvius erupted in 79 AD, causing the destruction of Pompeii, Herculaneum, Oplontis and much of the surrounding countryside. Vesuvius, a stratovolcano considered by many to be the world’s most dangerous volcano, straddles the African and Eurasian plates. The movement of these plates is for the most part smooth, but when the plates rub against each other, the ground shifts, causing earthquakes. The volcano itself serves as a vent that allows the molten core material from deep in the earth to escape, with often-catastrophic results. Vesuvius is part of an older volcano, Mount Somma. Formed from the collapse of Somma about 17,000 years ago, Vesuvius has a long eruptive history.  Its most recent eruption occurred in 1944, making it the only volcano on the European mainland to have erupted in the last 100 years. Since 79 AD, Vesuvius has erupted almost three dozen times, although only an eruption in 1631 AD claimed as great a loss of life.

The 79 AD eruption gave us the first surviving description of a volcanic eruption. In letters written to a friend years after the event, the Roman statesman Pliny the Younger described the eruption from his vantage point 18 miles across the Bay of Naples, likening the mushroom-shaped plume of ash to one of the pine trees so common in the region. It is in part because of his detailed description that we are able to accurately assess the sequence of events that led to the destruction of the cities of the Vesuvian region. Massive sustained eruptions with similarly high-altitude eruptive columns are called “Plinian” eruptions in his honor.

Vesuvius in 79 AD
Vesuvius' Victims

An excellent source of geologic information about Mt. Vesuvius can be found by visiting the website of the Osservatorio Vesuviano. The observatory, built on the slopes of the volcano, continuously monitors volcanic and seismic activity.