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Simultaneous rupture propagation through fault bifurcation of the 2021 Mw7.4 Maduo earthquake
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  • Shengji Wei,
  • Hongyu Zeng,
  • Qibin Shi,
  • Jihong Liu,
  • Heng Luo,
  • Wan-Lin Hu,
  • Yu Li,
  • Weitao Wang,
  • Zhangfeng Ma,
  • Jing Liu-Zeng,
  • Teng Wang
Shengji Wei
Earth Observatory of Singapore

Corresponding Author:[email protected]

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Hongyu Zeng
Asian School of the Environment, Nanyang Technological University
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Qibin Shi
Earth Observatory of Singapore, Nanyang Technological University
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Jihong Liu
Central South University
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Heng Luo
Peking University
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Wan-Lin Hu
Nanyang Technological University
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Yu Li
China Earthquake Networks Center
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Weitao Wang
Institute of Geophysics, China Earthquake Administration
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Zhangfeng Ma
Hohai University
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Jing Liu-Zeng
Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University
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Teng Wang
Peking University
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Abstract

Fault geometric complexity plays a critical role in earthquake rupture dimension. Fault bifurcations are commonly observed in earthquake geology, yet, robust kinematic rupture processes on bifurcated fault branches are largely missing, limiting our understanding of rupture dynamics and seismic hazard. Here, we holistically study the fault geometry and bilateral rupture of the 2021 Mw7.4 Maduo, China earthquake, that shows clear fault bifurcation near its eastern terminal. We integrate space geodesy imaging, back-projection of high-frequency teleseismic array waveforms, multiple point source and finite fault inversions, and constrain in detail the rupture process, in particular, through its fault bifurcation. Our models reveal a stable rupture speed of ~2.5 km/s throughout the entire rupture and a simultaneous rupture through fault branches bifurcated at 20°. The rupture on bifurcated faults radiated more high-frequency waves, especially from the stopping phases. The stopping phase on the southern branch likely stopped the rupture on the northern branch.