Rheological and tectonic implications of eastern Tibet: Insights from early aftershock sequences driven by afterslip following three 2021–2022 moderate-large events
Creators
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1.
Chengdu University of Technology
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2.
Central South University
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3.
King Abdullah University of Science and Technology
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4.
Massachusetts Institute of Technology
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5.
California Institute of Technology
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6.
China Earthquake Administration
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7.
Tongji University
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8.
Earth Observatory of Singapore
Abstract
Early aftershock sequences and afterslip provide key insights into crust rheology and the triggering mechanisms of seismicity sequences. Three recent moderate-large strike-slip earthquakes in eastern Tibet, including the 2021 Yangbi Mw 6.1, the 2021 Maduo Mw 7.4, and the 2022 Menyuan Mw 6.4 events, provide an ideal opportunity to investigate the driving processes of aftershocks and the regional crustal rheology. In this study, we inverted for the early afterslip and statistically analyzed the spatiotemporal evolution of these three aftershock sequences. Our results reveal a significant spatial complementarity between the relocated aftershocks, coseismic slip and early afterslip, suggesting aftershocks were triggered by afterslip driven by the coseismic stress changes. The depth of the aftershock sequences consistently shallows over time, which we interpret as a transient response of the brittle-ductile transition zone to early postseismic relaxation. For the first time, we quantify the depth-dependent variations of aftershock-derived rheological and frictional parameters along these three strike-slip faults in eastern Tibet. The recurrence times derived from early aftershocks are generally shorter than those estimated from geodetic or geological data, demonstrating that fault loading rates are not constant throughout the seismic cycle. This spatiotemporal comparison between aftershocks, coseismic slip and afterslip allows for the discrimination of different aftershock driving mechanisms. The framework presented here is generalized to other similar tectonic settings, providing a method to identify the dominant aftershock driving mechanism and to constrain the rheological properties, frictional parameters and recurrence times of regular earthquakes.
Copyright and License
© 2025 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/bync/4.0/).
Acknowledgement
We would like to extend our sincere thanks Sigurjón Jónsson, Yuan Gao, Zhuo Xiao, Xiaoning Su, Gaohua Zhu, Dezheng Zhao, Yaozong Zhou, Lei Zhao and Zilong He for their valuable suggestions, data sharing and communications during the development of this work. We acknowledge Crustal Movement Observation Network of China (CMONOC) for providing GNSS data at station QHME (https://data.earthquake.cn/datashare/report.shtml?PAGEID = siteInfo_jizhun). The GNSS postseismic data at station QHMD and H204 are available from Su et al., (2022) and Zhang et al., (2021a), respectively. The three aftershocks catalogues used in this study are respectively available from (Fan et al., 2022; Wang et al., 2021; Yang et al., 2021). The background seismicity catalogues for northeastern Tibet and southeastern Tibet is available from Xiao and Gao (2016) and Zhang et al., (2021b), respectively. Raw InSAR data are freely available (https://browser.dataspace.copernicus.eu/). This work was supported by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project (SKLGP2024Z016), the National Natural Science Foundation of China (No. 42174023), Sichuan Province Science Fund (No. 2024NSFSC0802). The figures were prepared using the Generic Mapping Tools software (https://www.generic-mapping-tools.org/) and the MATLAB software (https://www.mathworks.com/products/matlab.html).
Supplemental Material
Supplementary Data 1 : 1-s2.0-S1569843225004170-mmc1.docx
Contributions
Xiaoge Liu: Writing – review & editing, Writing – original draft, Visualization, Validation, Software, Methodology, Investigation, Funding acquisition, Formal analysis, Data curation, Conceptualization. Wenbin Xu: Writing – review & editing. William B. Frank: Writing – review & editing, Investigation, Formal analysis. Yijian Zhou: Writing – review & editing, Formal analysis, Data curation. Guoqiang Zhao: Writing – review & editing, Data curation. Lihua Fang: Writing – review & editing, Formal analysis. Hui Huang: Writing – review & editing, Formal analysis. Lijia He: Writing – original draft, Formal analysis. Weijun Gan: Writing – review & editing, Data curation.
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Additional details
Dates
- Available
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2025-08-05Version of record