Spatial and temporal distribution of earthquake ruptures in the eastern segment of the Altyn Tagh fault, China

We performed field investigations to reconstruct the paleoearthquake history of eastern segment of the Altyn Tagh fault, NW China. Investigation at the Saohu spring trench and Shibaocheng west trench sites result in the identification three well-resolved earthquakes, designated as events E-1, E-2, and E-3, within the last similar to 7000 years. Radiocarbon dates of detrital charcoal provide constraints on the timing of faulting events. The most recent surface-rupturing earthquake, event E-1 dated between 2720 and 2800 years (a) before present (BP), had a rupture length of similar to 83 km, extending from Hongliuxia to Bagexia, with a coseismic displacement of about 4.5 m. The penultimate event, E-2, occurred between 4180 and 4970 a BP and may have ruptured from Subei to Bagexia with a coseismic displacement of > 7 m. The third youngest event, E-3, occurred approximately 6440-7180 a BP and may have ruptured the whole segment from Subei to Kuantan mountain, with a coseismic displacement of > 10 m. Holocene earthquake recurrence behavior on the eastern segment of the Altyn Tagh fault conforms to a variable slip earthquake model. Together with previous studies of slip rate, the huge displacement deficit along the eastern segment indicates a high earthquake risk for the surrounding region; the fault has the potential to trigger earthquakes of greater than M7.8, or a period of clustered earthquake activity. The displacement deficit could also indicate that sub-faults in the western Qilian Mountains have absorbed more lateral extrusion of the plateau during the Holocene, which would result in a decreasing fault slip rate and weakening of the eastern extension or outward expansion of the Altyn Tagh fault.