Numerical simulation on the mechanism of the Madoi, Qinghai Ms7. 4 earthquake constrained by InSAR deformation

The Madoi M(S)7.4 earthquake occurred in Qinghai Province on 22 May 2021, which caused serious damage on the surface. In this work, using the interferometric synthetic aperture radar (InSAR) technology, coseismic surface deformation in ascending and descending directions of Sentinel-1, east-west and vertical directions were obtained, and the segmented structure of earthquake rupture surface was delineated. Constrained by the observed surface deformation from InSAR, a 3D viscoelastic finite element model considering the rupture characteristics of the Madoi earthquake was constructed. Then the 3D coseismic deformation and stress field of the Madoi earthquake were simulated. Results show that the Madoi earthquake is a typical left-lateral strike-slip faulting, in which the fault slip in the east is relatively large. The aftershocks of the Madoi earthquake are all distributed in the area where the Coulomb stress variation is negative, which indicates that the Madoi earthquake has fully released the accumulated strain on the fault and the occurrence of aftershocks in the future will spread towards the southwest and northeast. The occurrence of the Madoi earthquake has formed several stress enhancement areas, which indicates that the Madoi event has greatly increased the possibility of sliding of some other fault zones. The projection of Coulomb stress variation caused by the 2010 Yushu M7.3 earthquake on the main rupture surface of the Madoi earthquake is positive, which permits to speculate that the Yushu earthquake may have promoted the Madoi shock. This study can provide a quantitative reference for the judgment of aftershocks and possible surface damage following big earthquakes.