The 2022 Mw 6.6 Menyuan earthquake: An early-terminated runaway rupture by the complex fault geometry

Xu，Duyuan1,2; Li，Zhengbo1,2; Zhang，Zhenguo1,2; Yu，Houyun1,2; Xu，Jiankuan1,2; Yang，Zhigao3; Chen，Xiaofei1,2

2024-07-15

10.1016/j.epsl.2024.118746

Earth and Planetary Science Letters   影响因子和分区

0012-821X

The 2022 Mw 6.6 Menyuan earthquake, which caused unexpectedly large surface offsets (about 2.6–3.5 m) relative to the moment magnitude of this event, is one of the best-recorded strike-slip events in the northeastern Tibetan plateau. Although previous studies have revealed many kinematic features of this event, the mechanism and rupture dynamic characteristics underlying unexpectedly large surface dislocations need to be clarified. In this study, based on the grid search method, we conducted 61 dynamic rupture simulations considering terrain relief to screen out a preferred dynamic model that fits the geodetic, seismic, and geological observations well. The results show that the average stress drop of the nucleation part is relatively high (11 MPa), which could provide high initial rupture energy and give this event a chance to develop into a large earthquake. However, the rupture propagating eastward is slowed and terminated by two consecutive fault bends of about 10° each, and the westward propagating one might concentrate at a shallow depth (< 3 km) on the south secondary fault after it jumps over the stepover. These results imply that the complex fault geometry (the fault bend and stepover) might terminate the rupture early so that the observed magnitude of this event (Mw 6.6) is smaller than the estimated magnitude (Mw 7.1–7.2) based on the surface offsets. Our study again shows that, due to advances in computational power and observations (coverage and quality), physics-based dynamic rupture simulations have entered an era where it is possible to fit the observed data well, which is vital for further understanding the mechanisms of earthquakes.

Dynamic rupture simulations Earthquake physics Fault geometry effects The 2022 Menyuan earthquake The runaway rupture

SCI ; EI

英语

第一 ; 通讯

20241916057230

Dynamics ; Fault slips ; Geometry

Seismology:484 ; Earthquake Measurements and Analysis:484.1 ; Mathematics:921

GEOSCIENCES

2-s2.0-85192335543

Scopus

1.Guangdong Provincial Key Laboratory of Geophysical High-resolution Imaging Technology,Southern University of Science and Technology,Shenzhen 518055,China
2.Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen 518055,China
3.China Earthquake Networks Center,Beijing 100045,China

Xu，Duyuan,Li，Zhengbo,Zhang，Zhenguo,et al. The 2022 Mw 6.6 Menyuan earthquake: An early-terminated runaway rupture by the complex fault geometry[J]. Earth and Planetary Science Letters,2024,638.

Xu，Duyuan.,Li，Zhengbo.,Zhang，Zhenguo.,Yu，Houyun.,Xu，Jiankuan.,...&Chen，Xiaofei.(2024).The 2022 Mw 6.6 Menyuan earthquake: An early-terminated runaway rupture by the complex fault geometry.Earth and Planetary Science Letters,638.

Xu，Duyuan,et al."The 2022 Mw 6.6 Menyuan earthquake: An early-terminated runaway rupture by the complex fault geometry".Earth and Planetary Science Letters 638(2024).