As writen in Tolkien's Silmarillion:
Amon Amarth: "Mount Doom", the name given to Orodruin when its fires awoke again after Sauron's return from Numenor.
Orodruin: 'Mountain of Blazing Fire' in Mordor, in which Sauron forged the Ruling Ring;called also Amon Amarth, 'Mount Doom'.