Vesuvius, Ital. Vesuvio, only active volcano on the European mainland, S Italy, on the eastern shore of the Bay of Naples, SE of Naples. The height of the main cone changes with each eruption, varying within a few hundred feet of the 4,000-ft (1,219-m) level; in 1969 the height was 4,190 ft (1,277 m). The second summit, Monte Somma (3,770 ft/1,149 m) is a ridge that half encircles the cone and is separated from it by a valley (c.3 mi/5 km long). The sides of Vesuvius are deeply scarred by lava flow, but its lower slopes are extremely fertile, dotted with villages, and covered with vineyards which produce the famous Lachryma Christi wine. The base of the mountain (circumference c.45 mi/70 km) is encircled by a railroad, and a chairlift reaches almost to the rim of the crater (diameter c.2,300 ft/700 m). On the western slope, at 1,995 ft (608 m), there is a seismological observatory (built 1840-45). The outline of Vesuvius forms part of the backdrop of Naples; it is often surmounted by a faint plume of smoke.

The earliest recorded eruption (A.D. 79) was described by Pliny the Younger in two letters to Tacitus; the eruption buried Pompeii, Herculaneum, and Stabiae under cinders, ashes, and mud. Pliny the Elder was killed by the eruption, which he had come to investigate. Frequent eruptions have been recorded since Pompeii was destroyed, notably in 512, in 1631, six times in the 18th cent., eight times in the 19th cent. (notably in 1872), and in 1906, 1929, and 1944. The eruptions vary greatly in severity, but the geological record shows that Vevusius experiences a truly devastating eruption every 2,000-3,000 years.

Active volcano, eastern side of the Bay of Naples, southern Italy. It originated about 200,000 years ago; its current height of 4,198 ft (1,280 m) has varied considerably after each of its major eruptions; in 1900 it was 4,275 ft (1,303 m) high; in 1906, 3,668 ft (1,118 m) high; and in the 1960s, 4,203 ft (1,281 m) high. The cone is half-encircled on the northern side by Mount Somma, part of the wall of a large crater in which the present cone has formed. There have been numerous destructive eruptions; in AD 79 Pompeii and Herculaneum were destroyed, and in 1631 about 3,000 people were killed. The last major eruption occurred in 1944. More than two million people live in the area of Vesuvius, whose fertile slopes are covered with vineyards and orchards.

Learn more about Vesuvius with a free trial on Britannica.com.