On August 24 and 25, 79AD, Mt. Vesuvius erupted with a thermal energy a hundred thousand times greater than the Hiroshima bomb, killing approximately 16,000 of the areas 20,000 residents in Herculaneum and Pompeii.
The volcano erupted again in 1631, six times in the 18th century, eight times in the 19th century (notably in 1872), and in 1906, 1929, and 1944. There has been no eruption since 1944, and none of the post-79 eruptions were as large or destructive as the Pompeian one.
Today, this area is the most densely populated volcanic region in the world with a population of 3,000,000.