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We use Sentinel‐1 and ALOS‐2 Interferometric Synthetic Aperture Radar (InSAR), and Global Navigation Satellite System (GNSS) data to investigate the mechanisms of coseismic and postseismic deformation due to the 2021 M7.4 Maduo (China) earthquake. We present a refined coseismic slip model constrained by the rupture trace and precisely located aftershocks. The InSAR time series corrected for the atmospheric and decorrelation noise reveal postseismic line of sight displacements up to ∼0.1 m. The displacements are discontinuous along the fault trace, indicating shallow afterslip and velocity‐strengthening friction in the top 2–3 km of the upper crust. The magnitude of shallow afterslip is however insufficient to compensate for the coseismic slip deficit, implying substantial off‐fault yielding. The observed surface deformation does not exhibit obvious features that could be attributed to poroelastic effects. We developed a fully coupled model that accounts for both stress‐driven creep on a deep localized shear zone and viscoelastic relaxation in the bulk of the lower crust. The mid‐ to near‐field data can be reasonably well explained by deep afterslip and/or non‐Maxwellian visco‐elasticity. Our results suggest a power‐law stress exponent of ∼4–4.5 assuming a power‐law rheology, and transient and steady‐state viscosities of 1018 and 1019 Pa s, respectively, assuming a bi‐viscous (Burgers) rheology. However, a good fit to the GNSS data cannot be achieved assuming the bulk viscoelastic relaxation alone, and requires a contribution of deep afterlip and/or a localized shear zone extending through much of the lower crust. Plain Language Summary: A large earthquake occurred in the north‐east Tibetan Plateau (Qinghai Province, China) on 21 May 2021. We use data collected by orbiting satellites to measure subtle (millimeter to centimeter‐scale) displacements of the Earth's surface that occurred in 1 year following the Maduo earthquake. The observed rates and spatial patterns of surface displacements are used to infer the mechanisms of stress relaxation and mechanical properties of rocks at depth. We find evidence of continued slip on the fault that produced the Maduo earthquake, both near the surface, and below the seismogenic zone. Our results suggest that major faults that cut through the Tibetan Plateau are associated with deep roots that extend into the lower crust. The observed shallow slip is insufficient to compensate for the near‐surface slip deficit that accrued during the earthquake. This suggests that some amount of the near‐surface coseismic shear was distributed over a wider zone around the earthquake rupture. Key Points: We present a new method for modeling geometrically complex ruptures in heterogeneous media using distributed point sourcesPostseismic deformation is best explained by models that include a deep shear zone below the earthquake ruptureUp to ∼0.2 m of shallow afterslip occurred within 1 year after the earthquake, insufficient to compensate for the coseismic shallow slip deficit [ABSTRACT FROM AUTHOR]

The 2015 M7.2 Sarez (Pamir) earthquake occurred at the north‐west margin of the Tibetan Plateau. We use Sentinel‐1 and ALOS‐2 Synthetic Aperture Radar and Global Navigation Satellite System data to investigate coseismic and postseismic deformation due to the Sarez earthquake. Kinematic inversions show that the earthquake ruptured a ∼80 km long, sub‐vertical fault producing the maximum surface offset of 3–4 m on the south‐west and central fault segments. In contrast, the largest postseismic displacements are observed at the north‐east end of the earthquake rupture, predominantly on the west (hanging wall) side of the fault with an average rate of 20–30 mm/yr in the satellite line of sight. We use the derived coseismic and postseismic slip models to investigate mechanisms of time‐dependent relaxation, stress transfer and possible triggering relationships between the Sarez earthquake and a sequence of strong M6+ events that occurred within ∼100 km of the 2015 earthquake. We find that the near‐field postseismic displacements are best explained by shallow afterslip driven by the coseismic stress changes. The data also allow some contribution from poroelastic rebound, but do not show a clear signature of viscoelastic relaxation in the lower crust and upper mantle during the observation period, suggesting a lower bound on the effective viscosity of ∼1019 Pa s. A pair of M6+ events that occurred within 100 km and several months of the 2015 mainshock have experienced near‐zero and in some cases negative static Coulomb stress changes, suggesting either delayed dynamic triggering, or no relation to the mainshock. Plain Language Summary: Large earthquakes are often followed by slow deformation that results from redistribution and relaxation of coseismic stress changes in the host rocks. The patterns and rates of postseismic deformation can be used to learn about the properties of rocks at depth. We analyzed surface deformation that occurred during and after a major (magnitude 7.2) earthquake that occurred in the Pamir orogen at the north‐west margin of Tibet. We used radar imagery from satellites of the European and Japanese space agencies, as well as data from the Global Navigational Satellite System to measure subtle (centimeter‐scale) displacements of the Earth's surface that occurred within 100 km from the earthquake epicenter. A combination of coseismic and postseismic displacement data reveals that the earthquake rupture split into two branches as it was propagating from south‐west to north‐east. We found evidence of slow aseismic creep ("afterslip") at the north‐east end of the earthquake rupture. In contrast, we do not observe a broad pattern of displacements expected from enhanced viscous flow in the lower crust and/or upper mantle. The lack of the respective signal argues for a relatively strong "ductile" portion of the Tibetan lithosphere. Key Points: Near‐field postseismic deformation is dominated by shallow afterslip and poroelastic relaxation at the NE end of the earthquake ruptureData do not show a clear signal expected of viscoelastic relaxation, indicating effective viscosity of the lower crust >1019 Pa sWe investigate triggering relationships between the M7.2 and subsequent M6+ events that occurred within 1 year and 100 km of the mainshock [ABSTRACT FROM AUTHOR]

The 2021 Maduo earthquake ruptured a 150 km‐long left‐lateral fault in the northeast Tibet. We used Synthetic Aperture Radar data collected by the Sentinel‐1A/B satellites within days of the earthquake to derive a finite fault model and investigate the details of slip distribution with depth. We generated coseismic interferograms and pixel offsets from different look directions corresponding to the ascending and descending satellite orbits. At the eastern end the rupture bifurcated into two sub‐parallel strands, with larger slip on the northern strand. Inversions of coseismic displacements show maximum slip to the east of the epicenter. The averaged coseismic slip has a peak at depth of 3–4 km, similar to slip distributions of a number of shallow strike‐slip earthquakes. Postseismic observations over several weeks following the Maduo earthquake reveal surface slip with amplitude up to 0.1 m that at least partially eliminated the coseismic slip deficit in the uppermost crust. Plain Language Summary: A large earthquake occurred in a remote area of north‐east Tibet (Qinghai Province, China) on May 21, 2021. The earthquake produced a 150 km‐long rupture with surface offsets up to several meters. We used data collected by orbiting satellites to map motions of the Earth's surface that occurred during and shortly after the earthquake. The measured surface displacements were used to constrain the rupture geometry and slip distribution at depth. Best‐fitting models suggest that rupture occurred on a sub‐vertical fault steeply dipping to the north, with most of slip occurring to the east of the earthquake epicenter. The maximum coseismic slip occurred in the uppermost crust, in the depth interval of 3–4 km below the Earth's surface. A decrease in the fault offsets toward the Earth's surface is likely caused by an increased frictional resistance of the shallow layer to rapid coseismic slip. Satellite observations made in the first month after the earthquake reveal that the shallow part of the fault is slowly catching up with a deeper part to make up for the difference in the amount of slip produced during the earthquake. Key Points: We use Sentinel‐1 Synthetic Aperture Radar data to derive a finite fault model for the 2021 M7.4 Maduo (Qinghai, China) earthquakeThe along‐strike averaged coseismic slip has a maximum at depth of 3–4 km, with an amplitude of ∼2.5 mUp to 0.1 m of afterslip occurred on the fault trace in the first month following the earthquake [ABSTRACT FROM AUTHOR]