Mount Erebus

Mount Erebus (pronounced ĕr'ə-bəs) is a geographical location in Ross Island, Antarctica on Earth. Its height is around 12,500 feet. Erebus is the southernmost active volcano on Earth.

Background
Mount Erebus is currently the most active volcano in Antarctica. The summit contains a persistent convecting phonolitic lava lake, one of a very few long-lived lava lakes in the world. Characteristic eruptive activity consists of Strombolian eruptions from the lava lake or from one of several subsidiary vents, all lying within the volcano's inner crater.

First Battle of Earth
During the First Battle of Earth, the Covenant had set up an excavation operation, searching for the Ark Portal. Blue Team, comprised of Spartans -104, -058 and -043, stopped this excavation with the detonation of a HAVOK nuclear weapon, most likely doing significant damage to the mountain, although the nature of their mission gratifies this.