The catastrophic eruption of Mount Lamington in Papua New Guinea claims 2,942 lives.

In early January 1951, a series of minor explosions and earthquakes rocked Mount Lamington, a volcano in the Australian-administered Territory of Papua and New Guinea. Prior to the eruption, Mount Lamington was not recognized as a volcano due to the absence of historically recorded eruptions and dense vegetation cover. From January 15, volcanic activity intensified, and tall eruption plumes were generated. The largest eruption occurred on the morning of January 21 when a thick black plume of ash rose 15,000 metres (50,000 ft) into the atmosphere. The eruption collapsed a lava dome and produced a lethal pyroclastic flow that killed 2,942 people. In the years after the eruption, new lava domes formed and collapsed in succession. Activity persisted until July 1956. The eruption is the deadliest natural disaster in Australian history, as the region was under the rule of the Government of Australia.

January 21 is the 21st day of the year in the Gregorian calendar; 344 days remain until the end of the year.