The 1940 Vrancea earthquake, also known as the 1940 Bucharest earthquake, (Romanian: Cutremurul din 1940) occurred on Sunday, 10 November 1940, in Romania, at 03:39 (local time), when the majority of the population was at home.

The 1940 earthquake registered a magnitude of 7.7 on the moment magnitude scale, being the strongest earthquake recorded in the 20th century in Romania. Its epicenter lay in the Vrancea zone at a depth of about 133 km. The area of maximum intensity for this earthquake was 80,000 km2 and macroseismic effects were felt over an area of more than 2,000,000 km2. Effects were reported to the north as far away as Saint Petersburg, over 1,300 km away, with estimated seismic intensities of IV–V (MCS degrees), to the south, as far as Greece, to the east, up to the Kharkov–Moscow line, with estimated intensities of V–VI (MCS degrees), in the west, as far as Belgrade, Budapest and Warsaw.