Asymmetric Bilateral Rupture of the 2021 Mw 7.4 Maduo Earthquake in China and Association with Seismogenic Fault Structures

Abstract

Different frequency contents of seismic waveforms may reveal different earthquake rupture features, which could shed light on understanding the seismic rupture and its association with seismogenic fault structures. Here, we applied finite-fault inversions and compressive-sensing backprojection analyses to study the rupture process of the 2021 Mw 7.4 Maduo, China earthquake, using seismic data in different frequency ranges. Our results unveil an asymmetric west-to-east bilateral rupture of this earthquake, that is, the westward rupture hosted less coseismic slip and less energy radiations than the eastward one. The westward rupture may encounter a structural complexity, suppressing the propagation of the seismic rupture and radiating higher-frequency energy. Instead, the eastward rupture passed across a relatively continuous fault geometry and possibly reached super-shear velocities locally. The fault bifurcation at the eastern end may arrest the seismic rupture and facilitate its termination. We infer that asymmetric rupture features of the 2021 Maduo earthquake are associated with complex fault structures resulting from deformations caused by the northeastward growth of the Tibetan plateau.