Mount Doom bursts into flame
Event Type: Environment/Disease
Age: 3rd Age - The Stewards
2954 Mount Doom bursts into flame again.
The Return of the King, LoTR Appendix B, The Tale of Years: The Third Age
Turgon followed Túrin, but of his time it is chiefly remembered that two years ere his death, Sauron arose again, and declared himself openly; and he re-entered Mordor long prepared for him. Then the Barad-dûr was raised once more, and Mount Doom burst into flame, and the last of the folk of Ithilien fled far away.
The Return of the King, LoTR Appendix A, Annals of the Kings and Rulers: Gondor and the Heirs of Anárion: The Stewards
[Boromir says: ] `Smoke rises once more from Orodruin that we call Mount Doom.’
The Fellowship of the Ring, LoTR Book 2, Ch 2, The Council of Elrond