On December 1631 an unexpected eruption happened.
Mount Vesuvius is the only active volcano is Europe on mainland. It destroyed the cities of Pompeii and Herculaneum. Mt. Vesuvius is considered to be one of the most dangerous volcanoes. Scientist has detected a tear in African plate. The slap window" they that causes heat to come up and can cause violent explosions because it build pressure. The last serious eruption was in 1944.
Sites used: http://www.geo.mtu.edu/volcanoes/boris/mirror/mirrored_html/VESUVIO_79.html
http://www.naplesldm.com/oplontis.php
http://decodedpast.com/destruction-herculaneum-vesuvius-claimed-one-victim/7992
http://www.history.com/topics/ancient-history/pompeii
http://www.livescience.com/27871-mount-vesuvius-pompeii.html