Supershear Rupture During the 2021 Mw 7.4 Maduo, China, Earthquake

Combined with the multi-array back-projection and finite-fault joint inversion methods, we investigate the detailed spatiotemporal rupture complexity of the 2021 M-w 7.4 Maduo earthquake using seismic and geodetic data. Our results reveal that this earthquake ruptured bilaterally 170 km long fault segments with a duration of 38 s. The obtained back-projection results, specific aftershock signature of the supershear earthquake, and observations of far-field Love Mach waves consistently validate that this earthquake is a supershear event. Furthermore, by analyzing global large strike-slip earthquakes, we find that the moment-scaled radiated energies of previously well confirmed supershear earthquakes with relatively simple fault geometries are similar to that of the 2021 M-w 7.4 Maduo earthquake, which are significantly smaller than those of subshear strike-slip events. This new finding provides additional supporting evidence to validate the supershear rupture during the 2021 M-w 7.4 Maduo earthquake. Plain Language Summary On 21 May 2021, an M-w 7.4 earthquake ruptured the eastern part of the Bayan Har block in the Tibetan Plateau. To enhance our understanding of the earthquake source physics, we investigate the rupture process of this earthquake with teleseismic and regional broadband seismic, strongmotion, and InSAR observations. The combined analysis of multi-array back-projection imaging and finite-fault joint inversion reveal that the rupture of this earthquake propagated bilaterally towards both the west and the east. The estimated rupture length and duration are 170 km and 38 s, respectively. The obtained back-projection results and specific aftershock signature of the supershear earthquake together with the observations of Love Mach waves consistently suggest that this earthquake is a supershear event. Furthermore, the analysis of the 2021 M-w 7.4 Maduo earthquake and previous global large strike-slip earthquakes shows that supershear events with relatively simple fault geometries have significantly smaller moment-scaled radiated energies than those of subshear strike-slip events. This newly interesting finding can give a fresh perspective to provide additional supporting evidence for validating the potential supershear earthquakes in the future.

Automated summary

Using seismic and geodetic data, the detailed rupture characteristics of the 2021 M-w 7.4 Maduo earthquake were investigated. The results revealed that this earthquake was a supershear event, rupturing bilaterally along a 170 km fault segment. Furthermore, it was found that supershear earthquakes with simpler fault geometries have significantly smaller radiated energies.