Historical (Yuan Dynasty) Earthquake on the North Danghe Nanshan Thrust, Western Qilian Shan, China.

Historical archives of earthquake occurrence provide a millennial view of fault system behavior with precision beyond the capability of radiometric dating techniques. Understanding the long historical record of earthquake activity in China presents a great opportunity to develop such an archive. However, the complex distributed nature of faulting here leads to uncertainty and requires matching historic events to the paleoseismic record from fault excavations. We present paleoseismic evidence for the most recent rupture of the north Danghe Nanshan thrust (NDNT) and correlate the age of this event to nearby historical archives. We use high-resolution topography generated from airborne drone photography to measure an average coseismic fault throw of 0.8±0.2 m. Three trenches excavated across these small scarps show shortening of ~1.3 m, consistent with event magnitude of M_w 7.0±0.5 that probably ruptured the entire ~45-km-long northern strand of the eastern NDNT system. Geochronology data and the historical record from Dunhuang and Anxi together indicate that this event likely occurred at A.D. 1289, during the Yuan Dynasty. [ABSTRACT FROM AUTHOR]