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Science in China Series D: Earth Sciences

, Volume 51, Issue 8, pp 1064–1080 | Cite as

The deformation pattern and fault rate in the Tianshan Mountains inferred from GPS observations

  • ShaoMin Yang
  • Jie Li
  • Qi Wang
Article

Abstract

Based on GPS measurements conducted from 1992 to 2006, we present the current crustal movement velocity field for approximately 400 sites in the Tianshan Mountains and their adjacent areas, and estimate slip rates on the major faults using a 2-D elastic dislocation model. Our studies show slip rates within the range of 1–4 mm/a on the NW-SE trending strike-slip faults (such as Talas-Fergana fault) in the Tianshan Mountains. We also found the slip rates on the approximately WE-SN trending gently-dipping detachment fault vary from 10–13 mm/a for the southwest Tianshan Mountains to 2–5 mm/a for the eastern Tianshan Mountains, and to 6–12 mm/a for the Kyrgrz Tianshan. The GPS velocity field reveals that the total convergence is not uniformly distributed across the Tianshan Mountains, with 80%–90% of the N-S shortening absorbed along the southern and northern edges, and relatively little deformation accommodated within the interior. This first-order feature of strain pattern is explained best by underthrusting of adjacent blocks beneath the Tianshan Mountains along a basal detachment fault. We found the occurrence of historical M7–8 earthquakes somewhere in the locked ramp that connects the creeping and locking segments of the detachment, thereby resulting in elastic strain concentration and accumulation around it. The elastic strain confined in the upper crustal layer above the detachment ultimately releases through infrequent great earthquakes in the Tianshan Mountains, resulting in considerable folding and faulting at their margins. The Tianshan Mountains propagated outward and rose progressively as a wedge-shaped block.

Keywords

Tianshan Mountains GPS slip rates tectonic deformation 

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Copyright information

© Science in China Press and Springer-Verlag GmbH 2008

Authors and Affiliations

  1. 1.Research Center of Space Science and TechnologyChina University of GeosciencesWuhanChina
  2. 2.Institute of SeismologyChina Earthquake AdministrationWuhanChina
  3. 3.Earthquake Administration of Xinjiang Uygur Autonomous RegionUrumqiChina

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