An earthquake struck Turkey's eastern Erzincan Province at 1:57:23 a.m. on 27 December 1939 local time with a moment magnitude (Mw ) of 7.8 and maximum Mercalli intensity of XII (Extreme).

Surface rupturing, with a horizontal displacement of up to 3.7 meters, occurred in a 360 km long segment of the North Anatolian Fault Zone.

[5][6] The earthquake was the most severe natural loss of life in Turkey in the 20th century, with 32,968 dead,[6] and some 100,000 injured.

[14][better source needed] It resulted in a tsunami with heights of 1–3 m (3.3–9.8 ft) that hit the Black sea coast.

[15] Coulomb stress transfer from the 1939 earthquake promoted westward-progressing ruptures along the North Anatolian Fault.

[18][19] The total destruction of the earthquake prompted Turkey to adopt seismic building regulations.