Red River Fault

The Red River Fault, also called the Song Hong Fault, is a major strike slip fault running through Yunnan province in China and on into Vietnam, named for the Red River that flows through its valley. It accommodates the southward movement of continental China and works alongside the Sagaing Fault in Myanmar, which absorbs the northward movement of the Indian plate, causing the land trapped between the two faults to rotate clockwise. The fault was a sinistral, left lateral shear zone until the Miocene epoch, when it reactivated in its present dextral, right lateral strike slip form, and it produced the destructive 1970 Tonghai earthquake and has also been linked to earthquakes near Dali in 1925 and 2021.