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

Abstract

Abstract 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.

Keywords

• Yutian earthquake
• joint inversion
• interferometry
• broadband seismograms
• fault geometry
• rupture process