On 21 May 2021 (UTC), an MW 7.4 earthquake jolted the east Bayan Har block in the Tibetan Plateau. The earthquake received widespread attention as it is the largest event in the Tibetan Plateau and its surroundings since the 2008 Wenchuan earthquake, and especially in proximity to the seismic gaps on the east Kunlun fault. Here we use satellite interferometric synthetic aperture radar data and subpixel offset observations along the range directions to characterize the coseismic deformation of the earthquake. Range offset displacements depict clear surface ruptures with a total length of ～170 km involving two possible activated fault segments in the earthquake. Coseismic modeling results indicate that the earthquake was dominated by left-lateral strike-slip motions of up to 7 m within the top 12 km of the crust. The well-resolved slip variations are characterized by five major slip patches along strike and 64％ of shallow slip deficit, suggesting a young seismogenic structure. Spatial–temporal changes of the postseismic deformation are mapped from early 6-day and 24-day InSAR observations, and are well explained by time-dependent afterslip models. Analysis of Global Navigation Satellite System (GNSS) velocity profiles and strain rates suggests that the eastward extrusion of plateau is diffusely distributed across the east Bayan Har block, but exhibits significant lateral heterogeneities, as evidenced by magnetotelluric observations. The block-wide distributed deformation of the east Bayan Har block along with the significant co- and post-seismic stress loadings from the Madoi earthquake imply high seismic risks along regional faults, especially the Tuosuo Lake and Maqên–Maqu segments of the Kunlun fault that are known as seismic gaps.

Shuai Wang;Chuang Song;ShanShan Li;Xing Li

School of Geomatics Science and Technology,Nanjing Tech University,Nanjing 211816,China;COMET,School of Engineering,Newcastle University,Newcastle,NE17RU,UK;Physical Science and Engineering Division,King Abdullah University of Science and Technology,Thuwal,23955,Saudi Arabia

地球与行星物理（英文）

[1]Shuai Wang;Chuang Song;ShanShan Li;Xing Li-.Resolving co- and early post-seismic slip variations of the 2021 MW 7.4 Madoi earthquake in east Bayan Har block with a block-wide distributed deformation mode from satellite synthetic aperture radar data)[J].地球与行星物理（英文）,2022(01):108-122

jolted,postseismic,Tuosuo,Maq,Maqu

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