The Talas-Fergana Fault is the largest active strike-slip fault in the Tien Shan mountains of Central Asia, cutting for roughly 700 kilometres across Kyrgyzstan and neighbouring regions. It is a right-lateral fault that slices diagonally through the ranges, dividing the western and central Tien Shan and controlling the shape of the Fergana Basin.
The fault has an exceptionally long geological history, with cumulative right-lateral offset of well over 100 kilometres visible in displaced rock formations and river valleys. Its present-day slip rate is relatively slow, but its enormous length gives it the potential to host very large earthquakes.
Paleoseismic studies along the fault reveal evidence of past surface-rupturing earthquakes, and its trace passes near populated valleys and vital reservoirs in Kyrgyzstan. Combined with the many thrust faults of the surrounding Tien Shan, it makes this part of Central Asia one of the most seismically active continental interiors on Earth.