The 1931 Fuyun earthquake (富蕴地震) occurred on August 10, 1931 at 21:18 UTC. The epicenter was near Fuyun County of northern Xinjiang, China. It was a Mw 8.0 earthquake[4] and had a surface rupture of 171 km[1] with a maximal horizontal displacement of 14 m[5] along the Koktokay-Ertai fault zone (可可托海-二台断裂带).[6] The Koktokay-Ertai fault has a slip rate of 4±2 mm per year.[7] The rupture of this earthquake was caused by right-lateral strike-slip movement with normal component.[8] The rupture is well preserved and becomes one of the main features of the Koktokay National Geopark (可可托海国家地质公园) located in Koktokay.[9]