Short answers, pulled from the story.
Mount Vesuvius erupted after gas-rich magma rose to the surface, sending a column of stone, ash and volcanic gas 33 kilometers into the sky. The drop in pressure as the magma neared the surface let dissolved gases expand explosively, producing the violent, Plinian-style eruption that destroyed Pompeii and Herculaneum.
More than a thousand people are thought to have died when Mount Vesuvius erupted in AD 79, though the exact toll is unknown. By 2003, researchers had recovered around 1,044 body casts and scattered bones from about 100 more victims at Pompeii, plus the remains of roughly 332 people at Herculaneum.
Mount Vesuvius is considered one of the most dangerous volcanoes because roughly three million people live close enough to be affected by an eruption, with at least 600,000 inside the official danger zone. It is classified as a Decade Volcano, and its eruptions, known as Plinian eruptions, tend to be violent and explosive.
Pliny the Elder, commander of the Roman fleet at Misenum, sailed toward Stabiae to rescue his friend Rectina after Mount Vesuvius erupted. He died at Stabiae, and his body was found the next day with no visible injury; modern historians suspect a stroke or heart attack rather than the poisonous gas his nephew blamed.
Mount Vesuvius last erupted in March 1944, an eruption that destroyed the villages of San Sebastiano al Vesuvio, Massa di Somma and Ottaviano. As of July 2024, the Osservatorio Vesuviano classified the volcano at a Green Alert Level, indicating low volcanic activity.
The origin of Mount Vesuvius's name is uncertain, since ancient Campania was home to Greek, Oscan, Latin and Etruscan speakers. Proposed roots include Greek words for unquenchable or hurling violence, and older Indo-European words meaning to shine or burn, or hearth.