Long records of paleoearthquakes along the Xorkoli section of the Altyn Tagh fault

Long records of paleoearthquakes are essential for understanding earthquake recurrence behavior of active faults and evaluating regional seismic hazard.The Altyn Tagh fault, one of the longest strike-slip faults in the world, is a research focus among seismic geologists.The authors documented a long paleoseismic record along the Xorkoli section of central Altyn Tagh fault.Eight or probably nine earthquakes were identified based on event evidence in the forms of open fissures, folds, unconformities, and upward fault terminations, with ages of AD1598 (1491~1740), AD796 (676~926), 668 (732~590) BC, 956 (1206~716) BC, 1301 (1369~1235) BC, 2105 (2232~1987) BC, 2664 (2731~2601) BC, 2818 (2878~2742) BC and 3411 (3521~3205) BC respectively.The mean recurrence interval is 620±410 a with a coefficient of variation of 0.67, indicating that earthquake recurrence is weakly periodic.Synthesis of paleoseismic sites from the central Altyn Tagh fault indicates that not all earthquakes ruptured to the eastern end of the Xorkoli section, within the Aksay restraining bend.Given the 420 a elapsed time since the most recent event, a large surface-rupturing earthquake could occur at any time along the central section.