Research on deformation characteristics of the 2021 Qinghai Maduo MS7.4 earthquake through coseismic dislocation inversion

Over the past 70 years, the Qinghai Maduo Ms7.4 earthquake (May 22, 2021) has been the only earthquake with a magnitude of > 7 that has occurred within the Bayan Har Block. To investigate the deformation process of this earthquake, we acquired the Interferometric Synthetic Aperture Radar (InSAR) coseismic deformation field based on Sentinel-1 SAR images, which showed that the maximum line of sight (LOS) displacement was similar to 1 m. By combining this information with the results of our field investigation, the fault slip distributions were obtained by inversion using the single-and double-fault models, wherein the latter model showed better inversion results than that of the former. According to the inversion results, the overall rupture pattern was predominantly left-lateral strike-slip, with a released seismic moment of similar to Mw7.5. Specifically, the principal seismogenic fault had a strike of 283 degrees, dip of 91 degrees, and maximum slip of 4.87 m; the branch fault along the eastern segment of the rupture had a strike of 110 degrees, dip of 94 degrees, and maximum slip of 2 m. Conversely, the results derived from the Global Navigation Satellite System (GNSS) strain rate field before the earthquake indicated that the Maduo earthquake occurred in East Kunlun,which is characterized by the largest maximum shear strain rate. The strain accumulation rate (similar to 2. 5 x 10(-8)/yr) was significantly lower than that of the Xianshuihe fault zone on the southern boundary of the Bayan Har block and the East Kunlun fault zone on its northern boundary. Furthermore, pre-seismic deformation near the seismogenic fault was relatively gentle, showing partial late seismogenic characteristics. (c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.

Automated summary

The Qinghai Maduo Ms7.4 earthquake is the only earthquake with a magnitude of > 7 that has occurred within the Bayan Har Block in the past 70 years. Using InSAR technology and field investigations, researchers obtained the fault slip distributions and found that the earthquake was predominantly left-lateral strike-slip with a seismic moment of similar to Mw7.5. Furthermore, the Maduo earthquake occurred in East Kunlun, characterized by the largest maximum shear strain rate.