Abstract
The 2021 Qinghai Maduo MS7.4 earthquake was one of the strongest earthquakes that occurred in the Bayan Har block of the Tibetan Plateau during the past 30 years, which spatially filled in the gap of strong earthquake in the eastern section of the northern block boundary. In this study, the aftershock sequence within 8 days after the mainshock was relocated by double difference algorithm. The results show that the total length of the aftershock zone is approximately 170 km; the mainshock epicenter is located in the center of the aftershock zone, indicating a bilateral rupture. The aftershocks are mainly distributed along NWW direction with an overall strike of 285°. The focal depth profiles indicate that the seismogenic fault is nearly vertical and dips to southwest or northeast in different sections, indicating a complex geometry. There is an aftershock gap located to the southeast of the mainshock epicenter with a scale of approximately 20 km. At the eastern end of the aftershock zone, horsetail-like branch faults show the terminal effect of a large strike-slip fault. There is a NW-trending aftershock zone on the north side of the western section, which may be a branch fault triggered by the mainshock. The location of the aftershock sequence is close to the eastern section of the Kunlun Mountain Pass-Jiangcuo (KMPJ) fault. The sequence overlaps well with surface trace of the KMPJ fault. We speculate that the KMPJ fault is the main seismogenic fault of the MS7.4 Maduo earthquake.
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Acknowledgements
The earthquake bulletin data were from China Earthquake Networks Center and Qinghai Earthquake Agency. The authors sincerely thank the responsible editor and two anonymous reviewers for their constructive comments and suggestions; we are grateful to Prof. Yong Zheng, Prof. Yong ZHANG, Prof. Dun WANG, Prof Zhikun REN, Prof. Tao LI, Associate Prof. Zhimin LI and Associate Prof. Wanpeng FENG for their comments and suggestions in the preparation of the manuscript. We appreciate help from Dr. Ruijia WANG, Prof. Han YUE and Dr. Yijian ZHOU for polishing the language. The relocated aftershock sequence (Maduo_r-eloc.txt) and fault traces (Maduo_fault_trace.txt) can be downloaded from the supplements or website at http://www.chinarraydmc.cn/highlights/queryPage?mid=44&mpid=28. This work was supported by the National Key R&D Program of China (Grant No. 2018YFC1504103), the National Natural Science Foundation of China (Grant No. 41774067), the Special Fund of the Institute of Geophysics, China Earthquake Administration (Grant No. DQJB20X07) and S&T Program of Qinghai Province (Grant No. 2020-ZJ-752).
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Wang, W., Fang, L., Wu, J. et al. Aftershock sequence relocation of the 2021 MS7.4 Maduo Earthquake, Qinghai, China. Sci. China Earth Sci. 64, 1371–1380 (2021). https://doi.org/10.1007/s11430-021-9803-3
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DOI: https://doi.org/10.1007/s11430-021-9803-3