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EARTHQUAKE ›› 2023, Vol. 43 ›› Issue (4): 169-184.doi: 10.12196/j.issn.1000-3274.2023.04.011

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Research on the Three-Dimensional Deformation along the Maqin-Maqu Section of the East Kunlun Fault zone from InSAR

ZHANG Xia, DONG Yan-fang, HONG Shun-ying   

  1. Institute of Earthquake Forecasting, China Earthquake Administration, Beijing 100036, China
  • Received:2023-04-26 Revised:2023-06-06 Online:2023-10-31 Published:2023-12-29

Abstract: The East Kunlun Fault (EKF) is one of the most active left-lateral strike-slip faults located in the Qinghai-Tibet Plateau, and it is the northern boundary of the Bayan Har Block. The Maqin-Maqu segment of the East Kunlun Fault is a MW5.0 earthquake gap in the past 400 years. Based on PS-InSAR technology, we use Sentinel-1A/B Ascending and Descending SAR data from European Space Agency to obtain the LOS deformation velocity of the Maqin-Maqu segment. Combined with GNSS data, the three-dimensional velocity and fault-parallel velocity under the Eurasian reference frame are derived. Then, the Markov chain Monte Carlo method is used to invert the slipping rate and locking depth of the Maqin-Maqu segment and its surrounding faults. The results indicate that no obvious creep has been observed in the Maqin Maqu section. From west (Animaqing Mountain, 300 km away from the end of the East Kunlun fault) to east, the slipping rate gradually decreases from 4.7 mm/a to 2.3 mm/a. The Maqin-Maqu segment has a locking depth more than 10 km, resulting in sustained strain accumulation and closing to the recurrence. The cumulative seismic moments of both Maqin and Maqu segments reach ~1.00×1020 N·m, equalling to an MW7.3 earthquake. If the two segments rupture simultaneously, the released seismic moment energy is equivalent to an MW7.5 earthquake. The seismic risk of the Maqin-Maqu segment is worth poajing attention to.

Key words: Maqin-Maqu section, InSAR, Three-dimensional deformation, Fault coupling, Slip rate

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