The 1977 Vrancea earthquake occurred on 4 March 1977, at 21:22 local time, and was felt throughout the Balkans. It had a magnitude of 7.5, making it the second most powerful earthquake recorded in Romania in the 20th century, after the 10 November 1940 seismic event. The hypocenter was situated in the Vrancea Mountains, the most seismically active part of Romania, at a depth of 85.3 km.

The Socialist Republic of Romania was a Marxist–Leninist one-party socialist state that existed officially in Romania from 1947 to 1989. From 1947 to 1965, the state was known as the Romanian People's Republic. The country was an Eastern Bloc state and a member of the Warsaw Pact with a dominant role for the Romanian Communist Party enshrined in its constitutions. Geographically, RSR was bordered by the Black Sea to the east, the Soviet Union to the north and east, Hungary and Yugoslavia to the west, and Bulgaria to the south.