Shallow crustal velocity structures revealed by active source tomography and fault activities of the Mianning–Xichang segment of the Anninghe fault zone, Southwest China
The Anninghe fault is a large left-lateral strike-slip fault in southwestern China. It has controlled deposition and magmatic activities since the Proterozoic, and seismic activity occurs frequently. The Mianning−Xichang segment of the Anninghe fault is a seismic gap that has been locked by high str...
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| Format: | Article |
| Language: | English |
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Science Press
2022-02-01
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| Series: | Earth and Planetary Physics |
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| Online Access: | http://www.eppcgs.org/article/doi/10.26464/epp2022010?pageType=en |
| _version_ | 1811296423664156672 |
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| author | XiHui Shao HuaJian Yao Ying Liu HongFeng Yang BaoFeng Tian LiHua Fang |
| author_facet | XiHui Shao HuaJian Yao Ying Liu HongFeng Yang BaoFeng Tian LiHua Fang |
| author_sort | XiHui Shao |
| collection | DOAJ |
| description | The Anninghe fault is a large left-lateral strike-slip fault in southwestern China. It has controlled deposition and magmatic activities since the Proterozoic, and seismic activity occurs frequently. The Mianning−Xichang segment of the Anninghe fault is a seismic gap that has been locked by high stress. Many studies suggest that this segment has great potential for large earthquakes (magnitude >7). We obtained three vertical velocity profiles of the Anninghe fault (between Mianning and Xichang) based on the inversion of P-wave first arrival times. The travel time data were picked from seismograms generated by methane gaseous sources and recorded by three linearly distributed across-fault dense arrays. The inversion results show that the P-wave velocity structures at depths of 0−2 km corresponds well with the local lithology. The Quaternary sediments have low seismic velocities, whereas the igneous rocks, metamorphic rocks, and bedrock have high seismic velocities. We then further discuss the fault activities of the two fault branches of the Anninghe fault in the study region based on small earthquakes (magnitudes between \begin{document}$ {M}_{L} $\end{document} 0.5 and \begin{document}$ {M}_{L} $\end{document} 2.5) detected by the Xichang array. The eastern fault branch is more active than the western branch and that the fault activities in the eastern branch are different in the northern and southern segments at the border of 28°21′N. The high-resolution models obtained are essential for future earthquake rupture simulations and hazard assessments of the Anninghe fault zone. Future studies of velocity models at greater depths may further explain the complex fault activities in the study region. |
| first_indexed | 2024-04-13T05:48:18Z |
| format | Article |
| id | doaj.art-276043ae85ee42179e3305390ffe2aac |
| institution | Directory Open Access Journal |
| issn | 2096-3955 |
| language | English |
| last_indexed | 2024-04-13T05:48:18Z |
| publishDate | 2022-02-01 |
| publisher | Science Press |
| record_format | Article |
| series | Earth and Planetary Physics |
| spelling | doaj.art-276043ae85ee42179e3305390ffe2aac2022-12-22T02:59:52ZengScience PressEarth and Planetary Physics2096-39552022-02-016220421210.26464/epp2022010RA282-shaoxihuiShallow crustal velocity structures revealed by active source tomography and fault activities of the Mianning–Xichang segment of the Anninghe fault zone, Southwest ChinaXiHui Shao0HuaJian Yao1Ying Liu2HongFeng Yang3BaoFeng Tian4LiHua Fang5Laboratory of Seismology and Physics of Earth’s Interior, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, ChinaLaboratory of Seismology and Physics of Earth’s Interior, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, ChinaLaboratory of Seismology and Physics of Earth’s Interior, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, ChinaEarth System Science Programme, Faculty of Science, The Chinese University of Hong Kong, Hong Kong 999077, ChinaInstitute of Geophysics, China Earthquake Administration, Beijing 100089, ChinaInstitute of Geophysics, China Earthquake Administration, Beijing 100089, ChinaThe Anninghe fault is a large left-lateral strike-slip fault in southwestern China. It has controlled deposition and magmatic activities since the Proterozoic, and seismic activity occurs frequently. The Mianning−Xichang segment of the Anninghe fault is a seismic gap that has been locked by high stress. Many studies suggest that this segment has great potential for large earthquakes (magnitude >7). We obtained three vertical velocity profiles of the Anninghe fault (between Mianning and Xichang) based on the inversion of P-wave first arrival times. The travel time data were picked from seismograms generated by methane gaseous sources and recorded by three linearly distributed across-fault dense arrays. The inversion results show that the P-wave velocity structures at depths of 0−2 km corresponds well with the local lithology. The Quaternary sediments have low seismic velocities, whereas the igneous rocks, metamorphic rocks, and bedrock have high seismic velocities. We then further discuss the fault activities of the two fault branches of the Anninghe fault in the study region based on small earthquakes (magnitudes between \begin{document}$ {M}_{L} $\end{document} 0.5 and \begin{document}$ {M}_{L} $\end{document} 2.5) detected by the Xichang array. The eastern fault branch is more active than the western branch and that the fault activities in the eastern branch are different in the northern and southern segments at the border of 28°21′N. The high-resolution models obtained are essential for future earthquake rupture simulations and hazard assessments of the Anninghe fault zone. Future studies of velocity models at greater depths may further explain the complex fault activities in the study region.http://www.eppcgs.org/article/doi/10.26464/epp2022010?pageType=enanninghe fault zoneshallow crustp-wave velocitymethane gaseous sourcefault activity |
| spellingShingle | XiHui Shao HuaJian Yao Ying Liu HongFeng Yang BaoFeng Tian LiHua Fang Shallow crustal velocity structures revealed by active source tomography and fault activities of the Mianning–Xichang segment of the Anninghe fault zone, Southwest China Earth and Planetary Physics anninghe fault zone shallow crust p-wave velocity methane gaseous source fault activity |
| title | Shallow crustal velocity structures revealed by active source tomography and fault activities of the Mianning–Xichang segment of the Anninghe fault zone, Southwest China |
| title_full | Shallow crustal velocity structures revealed by active source tomography and fault activities of the Mianning–Xichang segment of the Anninghe fault zone, Southwest China |
| title_fullStr | Shallow crustal velocity structures revealed by active source tomography and fault activities of the Mianning–Xichang segment of the Anninghe fault zone, Southwest China |
| title_full_unstemmed | Shallow crustal velocity structures revealed by active source tomography and fault activities of the Mianning–Xichang segment of the Anninghe fault zone, Southwest China |
| title_short | Shallow crustal velocity structures revealed by active source tomography and fault activities of the Mianning–Xichang segment of the Anninghe fault zone, Southwest China |
| title_sort | shallow crustal velocity structures revealed by active source tomography and fault activities of the mianning xichang segment of the anninghe fault zone southwest china |
| topic | anninghe fault zone shallow crust p-wave velocity methane gaseous source fault activity |
| url | http://www.eppcgs.org/article/doi/10.26464/epp2022010?pageType=en |
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