The 2021 Mw 7.3 Madoi, China Earthquake: Transient Supershear Ruptures on a Presumed Immature Strike-Slip Fault

Chuang Cheng1; Dun Wang1; Qiang Yao1; Lihua Fang2; Shiqing Xu3; Zihao Huang1; Tonghui Liu1; Zhifeng Wang1; Xiaolin Huang1

2023-02-01

10.1029/2022JB024641

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH   Impact Factor & Quartile

2169-9313

2169-9356

We used seismic data recorded at local and teleseismic distances to analyze the May 22, 2021 Mw 7.3 Madoi, China earthquake sequence, which occurred along a low-slip-rate (0.3-1.0 mm/yr) and small-cumulative-displacement (4-5 km) fault & mdash;the Kunlun Mountain Pass-Jiangcuo Fault (KMPJF). We first restored the clipped waveforms recorded at local distances, and obtained more accurate phase arrivals for relocating the earthquake sequence. The relocated earthquakes illuminate a similar to 170 km-long complex northwest-southeast (NW-SE) striking ruptured fault with apparent bifurcated ends at both tips and variations in dip angles along strike. We further performed backprojection analyses to image the rupture process of the mainshock using seismic data recorded at four teleseismic arrays (Europe, Australia and Southeast Asia, Japan, and Alaska). The results show that the earthquake propagated bilaterally in the NW and SE directions with maximum rupture speeds of similar to 4.0 km/s. This observation was further refined by multiple array backprojections onto the fault that was determined by the fine relocations of the earthquake sequence. Synthetic and realistic tests validated the resolutions of the backprojection analyses (within 5-20 km). The fast supershear rupture speeds were only transient but exhibited spatial correlation with the geometric complexities of the KMPJF. This suggests that the transient supershear ruptures are due to the varying geometry of the KMPJF, which is likely an immature fault. Our results suggest that the potential for supershear ruptures along immature strike-slip faults should be emphasized in earthquake hazard assessment.

Madoi earthquake backprojection source process supershear rupture earthquake relocation

SCI

English

NI Journal Papers

Corresponding

National Key R & D Program of China["2018YFC0603500","2021YFC3000702"] ; NSFC["41874062","41922025","42074048"]

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:000933666600001

AMER GEOPHYSICAL UNION

GEOSCIENCES

Web of Science

1.Badong National Observation and Research Station of Geohazards, School of Earth Sciences, China University of Geosciences, Wuhan, China
2.Institute of Geophysics, China Earthquake Administration, Beijing, China
3.Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen, China

Chuang Cheng,Dun Wang,Qiang Yao,et al. The 2021 Mw 7.3 Madoi, China Earthquake: Transient Supershear Ruptures on a Presumed Immature Strike-Slip Fault[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2023,128(2).

Chuang Cheng.,Dun Wang.,Qiang Yao.,Lihua Fang.,Shiqing Xu.,...&Xiaolin Huang.(2023).The 2021 Mw 7.3 Madoi, China Earthquake: Transient Supershear Ruptures on a Presumed Immature Strike-Slip Fault.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,128(2).

Chuang Cheng,et al."The 2021 Mw 7.3 Madoi, China Earthquake: Transient Supershear Ruptures on a Presumed Immature Strike-Slip Fault".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 128.2(2023).