资源环境科技发展态势分析平台

The slip rate and its spatial variations of the Kunlun fault (KLF) play important roles in the tectonic evolution of the northeastern Tibetan Plateau. Here the slip rate of the Tuosuo Lake (TL) segment of the KLF, which remains controversial from various geological observations, is investigated with a dense Global Positioning System observation profile. With a viscoelastic earthquake-cycle deformation model, the slip rate of the TL segment is estimated to be 5.5 +/- 0.7 mm/a, in comparison with an overestimated value of 9.2 +/- 1.1 mm/a from an elastic model. Combined with previous results, we infer that the slip rate of the KLF likely decreases gradually from the TL segment toward the eastern tip, rather than remaining uniform along the fault or decreasing rapidly within the easternmost 150 km. The estimated lower crust viscosity (similar to 10(18) Pa.s) agrees with values inferred from postseismic studies, which suggests a weak ductile lower crust in this region.

Plain Language Summary The Kunlun fault (KLF) is one of the major left-lateral strike-slip faults on the Tibetan Plateau and accommodates a significant portion of the plateau's eastward motion. The slip rate and its spatial variations along the KLF play important roles in understanding the associated tectonic evolution, crustal deformation, and seismic activity. However, how the slip rate varies along the fault remains controversial. Here a dense Global Positioning System velocity profile across the Tuosuo Lake segment is used to probe the slip rate of the eastern KLF. The results inferred from a viscoelastic earthquake-cycle deformation model suggest that the slip rate of the KLF decreases gradually from the Tuosuo Lake segment toward its eastern tip, rather than remaining uniform along the fault or decreasing rapidly within the easternmost 150km of the fault as inferred previously from different observations. Our results also highlight the viscoelastic relaxation effect during the earthquake cycle.