Ground Zero is the point of impact of a Leviathan meteor on Tallon IV, mentioned in a scan in the Map Facility room of the Frigate Orpheon in Metroid Prime. Surrounding the site is the Phazon Mines, built and used by Space Pirates for extracting the radioactive substance known as Phazon. The massive impact area is visible through windows in elevator shafts used to connect between floors in the mines.
"Tallon IV Ground Zero area secure. Crater radiation readings normal."