Vesuvius

For the robot of the same name, see Vesuvius (robot).

Vesuvius was a volcano located in Italy. In 79AD, Vesuvius erupted, destroying the Roman city of Pompeii. Two incarnations of the Doctor, the seventh and the tenth, were present during the eruption, though both managed to avoid encountering each other. (BFA: The Fires of Vulcan, DW: The Fires of Pompeii)

In an alternate timeline, Vesuvius took much longer to erupt, and the people of Pompeii evacuated in their boats. (PDA: The Algebra of Ice)

The rocklike Pyroviles used a hollowed-out chamber within the mountain as part of their plan to terraform the Earth into a rocky wasteland to replace their lost homeworld, Pyrovillia. The Pyroviles used the energy from the volcano to power their operations, which had the effect of cancelling out the eruption. This presented the Doctor with a moral dilemma: by stopping the Pyroviles he would trigger the eruption. He would have to allow Pompeii to be destroyed in order to save the world. With the support of his companion, Donna Noble, the Doctor triggered the eruption. The explosion was as powerful as 24 nuclear bombs and cracked open a rift in time which lasted for a second due to the sheer force of the blast. The rift's effects rippled backward in time, allowing the people of Pompeii to see the future. The eruption also destroyed the Pyroviles. Although almost all of the residents of Pompeii perished, one family was saved by the Doctor. (DW: The Fires of Pompeii)

Captain Jack Harkness claimed to have used the eruption as part of one of his cons against the Time Agency, though he would never stay for "Volcano Day". (DW: The Doctor Dances)