Slip Model of the 2020 Yutian (Northwestern Tibetan Plateau) Earthquake Derived From Joint Inversion of InSAR and Teleseismic Data.

Interferometric synthetic aperture radar and teleseismic P‐wave data were combined to investigate the source rupture characteristics of the 2020 Mw 6.3 Yutian, China, earthquake. We first utilized the near‐field displacements together with 29 broadband teleseismic P waveforms to investigate the uniform slip model by using a Bayesian bootstrap optimization nonlinear inversion method to resolve the nucleation point location, origin time and fault geometrical parameters. Based on these results, the kinematic rupture process of the earthquake was inverted. We conclude that the 2020 Yutian earthquake occurred on a west‐dipping blind normal fault with a dip of ∼60° at the junction of Bayan Har block (BHB) and western Kunlun block (WKB). The rupture nucleation point was located at longitude = 82.435°E, latitude = 35.619°N, and a depth of 6.377 km, making it shallower than estimated from other point source inversions. The earthquake started at 21:05:20 UTC on June 25, 2020 and was delayed by ∼2.07 s compared with GeoForschungsZentrum. The rupture lasted for ∼12 s, with a total seismic moment of ∼3.28 × 1018 Nm, corresponding to a moment magnitude of 6.3. The slip was mainly confined between ∼3.0 and 9.0 km in depth and the peak slip was ∼1.40 m, which occurred at a depth of ∼6.377 km. The slip was predominantly normal slip with slight right‐lateral strike‐slip components, which agrees with the southeastward movement of the BHB relative to the WKB. Plain Language Summary: The June 25, 2020 Mw 6.3 Yutian earthquake occurred on a normal fault within the northwestern Tibetan Plateau, a region characterized by EW extension. Because the rough focal mechanism solutions and source locations based on seismic wave data reported by several institutes are different, they cannot be used to create a reliable fault model for inverting the kinematic rupture process of this moderate earthquake. The initial rupture point and origin time, which are the prior information needed for revealing the slip characteristics, are also unclear. To resolve these rupture parameters, both Sentinel‐1 interferometric synthetic aperture radar and teleseismic P‐wave data were collected. We found that the rupture mainly occurred in the shallow part of a ∼60° west‐dipping normal fault, the nucleation point was near the point of maximum slip, and the slip lasted ∼12 s and extended northward and southward. Our research has important significance for understanding earthquake disasters and deformation mechanisms of faults within the northwestern Tibetan Plateau. Key Points: Both interferometric synthetic aperture radar and teleseismic P wave are used to resolving the ambiguity of fault geometryThe rupture nucleation point and origin time were clarified by a Bayesian bootstrap optimization inversion methodRupture process of this earthquake is predominantly normal‐sip with slight right‐lateral strike‐slip components [ABSTRACT FROM AUTHOR]