Using space observation techniques to study temporal and spatial characteristics of seismogenic process, occurrence and deformation of the Qinghai Madoi Mw7. 4 earthquake

In order to reveal the characteristics of pre-seismic deformation and co-seismic rupture of the 2021 Qinghai Madoi M(w)7. 4 earthquake, we systematically collect the GNSS data from Qinghai CORS and Crustal Movement Observation Network of China and the SAR data from Sentinel-1 and ALOS-2 satellites, and obtain the dynamic deformation field of the Madoi earthquake by the integrated processing of multi-source data. The pre-seismic GNSS deformation field shows that the Madoi focal area is located at the edge of the high-value region of shear deformation in the north of the earthquake, and sinistral shear strain was accumulated there before the earthquake. The 3-D co-seismic deformation field shows that the KunlunshanPass-Jiangcuo fault has a significant sinistral rupture, and the co-seismic deformation mainly occurs within 100 km from the fault with a maximum horizontal component of 2.4 m. The vertical co-seismic deformation mainly occurs in the vicinity of the fault, and shows alternately positive and negative variation from one side of the fault to the other, which reveals the spatial diversity of dip angles of the ruptured fault. The result of the joint inversion of GNSS and InSAR shows that the rupture of the Madoi earthquake reaches the surface, which is mainly distributed above 15 km depth, with the maximum slip value at about 4 m, and the moment magnitude is about 7.4. The rupture along the fault strike shows an obvious segmental characteristic, and five regions with significant slip values are distributed discontinuously.

Automated summary

In this study, by integrating multiple data sources, the characteristics of pre-seismic deformation and co-seismic rupture of the 2021 Qinghai Madoi earthquake were revealed. The pre-seismic deformation showed accumulated sinistral shear strain in the region before the earthquake, and the co-seismic deformation mainly occurred within 100 km from the fault. The vertical deformation exhibited alternating positive and negative variations. The findings are of great significance for understanding seismic dynamic deformation.