Average Slip Rate and Recurrence Interval of Large-Magnitude Earthquakes on the Western Segment of the Strike-Slip Kunlun Fault, Northern Tibet

Abstract

Interpretations of satellite remote sensing images, field and trench excavation investigations, and radiocarbon dates constrain the Holocene slip rate and average recurrence interval of large earthquakes on the western segment of the strike- slip Kunlun fault related with the 2001 M w 7.8 Central Kunlun earthquake, northern Tibet. Streams and gullies developed on the alluvial fans having an average 14 C age of ∼7000 years are sinistrally offset by up to 115 m along the Kunlun fault. This constrains a slip rate of 16.4 mm/yr for the past ∼7000 years. Trenches and 14 C ages reveal that at least four seismic faulting events occurred in the past 6200 years and that the penultimate event prior to the 2001 M w 7.8 earthquake occurred during the past 400 years with an average left-lateral offset of 4–5 m. Coupling the slip rate of 16.4 mm/yr with the average offset of 4–5 m produced by individual large earthquakes, it is estimated that the average recurrence interval of large earthquakes is 300–400 years on the western segment of the Kunlun fault. Our results confirm that the Kunlun fault plays an important role as a major strike-slip fault in accommodating the horizontal eastward extrusion of Tibet.