The Xianshuihe Fault is a left-lateral strike-slip fault that runs about 350 kilometres through the eastern Tibetan Plateau in western Sichuan. It helps accommodate the eastward escape of crustal material squeezed out by the collision of India with Asia, slipping horizontally at roughly 10 to 15 millimetres per year, one of the fastest rates in the region.
The fault forms a curving belt of narrow valleys and pull-apart basins near towns such as Kangding and Luhuo, dividing the Sichuan-Yunnan block from the Bayan Har block to the north. Its several segments have each ruptured repeatedly, making it one of the most seismically active faults in mainland China.
Historical records list a long series of damaging earthquakes along the fault, including the 1786 Kangding event whose landslide dam later collapsed and drowned thousands downstream, and the 1973 Luhuo earthquake of magnitude 7.6. The dense modern population of the Kangding corridor keeps the fault a serious hazard today.