The Red River Fault or Song Hong Fault is a major fault in Yunnan, China and Vietnam which accommodates continental China's (Yangtze Plate) southward movement It is coupled with that of the Sagaing Fault in Burma, which accommodates the Indian plate's northward movement, with the land (Indochina) in between faulted and twisted clockwise. It was responsible for the 1970 Tonghai earthquake.
It is named after the Red River which runs through its rift valley.
Red River is a sinistral strike-slip fault situated at a NW-SE orientation.