Late Quaternary Slip Behavior of the Jinqianghe Fault in the Middle Qilian–Haiyuan Fault Zone, Northeastern Tibetan Plateau

The Qilian–Haiyuan fault zone in the northeastern Tibetan Plateau has been the source of strong earthquakes in the region. In its middle segment, the Jinqianghe fault is an important active fault within the Tianzhu seismic gap; however, little is known about its slip behavior. To present a new horizontal displacement distribution along this fault, we used WorldView-2 stereo pairs and unmanned aerial vehicle-based photogrammetry to construct digital elevation models to obtain a detailed tectono-geomorphic interpretation and geomorphic offsets. The offset marker measurements yielded 135 geomorphic displacements and 8 offset clusters. Radiocarbon dating was used to establish the regional age sequence of the geomorphic units in offset fluvial terraces at four study sites. The displacements and ages linked the offset clusters with the geomorphic unit sequence; the Holocene strike-slip rate of the Jinqianghe fault was estimated to 4.8–5.6 mm/a at ~4–12 ka and 2.9–4.7 mm/a from ~4 ka. Three recent earthquakes (with a recurrence interval of ~1000 years) represent an active seismic period, revealing the potential seismic hazard along this fault because it has not ruptured in the last 1500 years.