Abstract
The ENE striking Longmu Co fault and the North Altyn Tagh left-lateral slip fault have led to the complex regional structure in the northwestern Tibetan Plateau, resulting in a series of normal faulting and strike slip faulting earthquakes. Using both the ascending and descending Sentinel-1A/B radar images, we depict the coseismic deformation caused by the 2020 Yutian Mw 6.4 earthquake with a peak subsidence of ~ 20 cm. We determine the seismogenic fault geometry by applying the Bayesian approach with a Markov Chain Monte Carlo sampling method, which can better characterize the posterior probability density functions of the source model parameters. The estimation results reveal that the earthquake is a normal faulting event with a moderate strike slip component. Based on the optimal fault geometry model, we extend the fault plane and invert for the distributed coseismic slip model. The optimal slip model shows that the coseismic slip is mainly concentrated at shallow depths of 3–10 km with a maximum slip of ~ 1.0 m. Our preferred geodetic coseismic model exhibits no surface rupture, which may likely be due to the shallow slip deficit in the uppermost crust. We calculate the combined loading effect of the Coulomb failure stress changes induced by the coseismic dislocations and postseismic viscoelastic relaxation of the 2008 Mw 7.1, 2012 Mw 6.4 and 2014 Mw 6.9 Yutian events. Our study demonstrates that the three preceding major Yutian shocks were insufficient to trigger the 2020 Yutian earthquake, which we consider perhaps reflects the natural release of elastic strain accumulated mainly through localized tectonic movement. We attribute the 2020 Yutian event to the release of extensional stress in a stepover zone controlled by the Longmu Co and the North Altyn Tagh sinistral strike slip fault systems. The seismic risk in the southwest end of the North Altyn Tagh fault has been elevated by the Yutian earthquake sequences, which require future attention.
Highlights
Over the past two decades, a series of moderate-sized and strong earthquakes have occurred at the boundary surrounding area of the Bayan Har block in the central and northern Tibetan Plateau, which has become the most active block in the plateau, significantly increasing the seismicity around the block (Elliott et al 2010; Lin et al 2011; Ren et al 2013; Wu et al 2014)
Our study demonstrates that the two preceding major Yutian shocks were insufficient to trigger the 2020 Yutian earthquake, which we consider perhaps reflects the natural release of elastic strain accumulated mainly through localized tectonic movement
Constrained by the near-field ascending and descending Sentiel-1A/B radar images, we presented the Interferometric Synthetic Aperture Radar (InSAR) coseismic deformation of the 2020 Mw 6.4 Yutian earthquake, which provided the opportunity to probe the seismic activity and tectonic context of the triple junction area in the northwestern Tibetan Plateau
Summary
Over the past two decades, a series of moderate-sized and strong earthquakes have occurred at the boundary surrounding area of the Bayan Har block in the central and northern Tibetan Plateau, which has become the most active block in the plateau, significantly increasing the seismicity around the block (Elliott et al 2010; Lin et al 2011; Ren et al 2013; Wu et al 2014). The determination of the source parameters and coseismic slip distribution of the 2020 Ms 6.4 Yutian event is crucial to enhance our understanding of the seismogenic fault and the dynamic mechanism of the local regional tectonic evolution, and will contribute to elevate the potentially seismic hazard in the triple junction area of the North Altyn Tagh, Karakax, and Longmu Co fault systems. The tectonic background of a series of the clustered Yutian earthquake sequences in the northwestern Tibetan Plateau is discussed
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
