Coseismic and Early Postseismic Deformation Due to the 2021 M7.4 Maduo (China)...

Jin, Z., and Y. Fialko (2023), Coseismic and Early Postseismic Deformation Due to the 2021 M7.4 Maduo (China) Earthquake, Geophys. Res. Lett..

The 2021 Maduo earthquake ruptured a 150 km-long left-lateral fault in the northeast Tibet. We used Synthetic Aperture Radar data collected by the Sentinel-1A/B satellites within days of the earthquake to derive a finite fault model and investigate the details of slip distribution with depth. We generated coseismic interferograms and pixel offsets from different look directions corresponding to the ascending and descending satellite orbits. At the eastern end the rupture bifurcated into two sub-parallel strands, with larger slip on the northern strand. Inversions of coseismic displacements show maximum slip to the east of the epicenter. The averaged coseismic slip has a peak at depth of 3–4 km, similar to slip distributions of a number of shallow strike-slip earthquakes. Postseismic observations over several weeks following the Maduo earthquake reveal surface slip with amplitude up to 0.1 m that at least partially eliminated the coseismic slip deficit in the uppermost crust. Plain Language Summary A large earthquake occurred in a remote area of north-east Tibet (Qinghai Province, China) on May 21, 2021. The earthquake produced a 150 km-long rupture with surface offsets up to several meters. We used data collected by orbiting satellites to map motions of the Earth's surface that occurred during and shortly after the earthquake. The measured surface displacements were used to constrain the rupture geometry and slip distribution at depth. Best-fitting models suggest that rupture occurred on a sub-vertical fault steeply dipping to the north, with most of slip occurring to the east of the earthquake epicenter. The maximum coseismic slip occurred in the uppermost crust, in the depth interval of 3–4 km below the Earth's surface. A decrease in the fault offsets toward the Earth's surface is likely caused by an increased frictional resistance of the shallow layer to rapid coseismic slip. Satellite observations made in the first month after the earthquake reveal that the shallow part of the fault is slowly catching up with a deeper part to make up for the difference in the amount of slip produced during the earthquake.

Research Program: 
Earth Surface & Interior Program (ESI)