Late quaternary slip rate of the east segment of the Yushu fault in the central-eastern Tibetan Plateau

摘要

The Yushu fault is a mainly left-lateral strike slip fault with some normal component within the Ganzi-Yushu fault system in central-eastern Tibetan Plateau. In 2010, the catastrophic Yushu Ms 7.1 earthquake occurred along this fault, causing approximately 3000 casualties and widespread damages; however, the late Quaternary slip rate of this fault was not tightly constrained due to poor research. Based on the interpretation of satellite images, field measurement of the offset of terrace risers, optically stimulated luminescence (OSL) and radiocarbon (C-14) dating of terrace ages, the late Quaternary slip rate of the east segment of the Yushu fault is estimated to be 6.8-8.2 mm/yr. In consideration of the partitioning effect of the Batang fault south of Yushu, the late Quaternary slip rate of the entire Yushu segment is approximately 9-12 mm/yr. Given the characteristic offset of about 6-8 m, the recurrence interval of large earthquakes along the Yushu fault is estimated to be approximately 750-1150 yr. This research provides basic parameters for the long-term seismic hazards assessment of the Yushu area and implies the limited southeastward extrusion rate (similar to 10 mm/yr) of Qiangtang block relative to the Bayan Har block.