Imaging Shallow Velocity Structure of an Inactive Fault by Airgun Seismic Source: A Case Study of Xiliushui Fault in Qiliang Mountain
We observed high-quality waves from a repeatable airgun seismic source recorded by a linear ultra-dense seismic array across the Xiliushui fault zone, one of the inactive faults in the Qilian Mountain, on the northeastern margin of the Tibetan Plateau, China. We used Snell’s law of seismic ray propa...
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2025-01-01
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| author | Manzhong Qin Baichen Wu Yi Wang Xueyi Shang Yuansheng Zhang Xuzhou Liu Xiao Guo Rui Zou Yahong Wang Dianfeng Sun |
| author_facet | Manzhong Qin Baichen Wu Yi Wang Xueyi Shang Yuansheng Zhang Xuzhou Liu Xiao Guo Rui Zou Yahong Wang Dianfeng Sun |
| author_sort | Manzhong Qin |
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| description | We observed high-quality waves from a repeatable airgun seismic source recorded by a linear ultra-dense seismic array across the Xiliushui fault zone, one of the inactive faults in the Qilian Mountain, on the northeastern margin of the Tibetan Plateau, China. We used Snell’s law of seismic ray propagation to determine a simplified ambient velocity model. Based on the flexible and precise spectral element method, we computed broadband synthetic seismograms for a shallow low-velocity fault zone (FZ) to model the direct P-wave travel time delay and incident angle of the wavefield near the FZ. The FZ extent range and boundaries were inverted by apparent travel time delays and amplification patterns across the fault. According to prior information on the properties of the direct P-waves, we could constrain the inverse modeling and conduct a grid search for the fault parameters. The velocity reduction between the FZ and host rock, along with the dip angle of the FZ, were also constrained by the P-wave travel time delay systematic analysis and incoming angle of the P-waves. We found that the Xiliushui fault has a 70~80 m-wide low-velocity fault damage zone in which the P-wave velocity is reduced to ~40% with respect to the host rock. The fault damage zone dips ~35°southwest and extends to ~165 m in depth. The repeatability and environment protection characteristics of the airgun seismic survey and the economic benefits of a limited number of instruments setting are prominent. |
| format | Article |
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| institution | Kabale University |
| issn | 2076-3263 |
| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-53e630727bb2420f90c8566af9f8702c2025-01-24T13:34:10ZengMDPI AGGeosciences2076-32632025-01-011511610.3390/geosciences15010016Imaging Shallow Velocity Structure of an Inactive Fault by Airgun Seismic Source: A Case Study of Xiliushui Fault in Qiliang MountainManzhong Qin0Baichen Wu1Yi Wang2Xueyi Shang3Yuansheng Zhang4Xuzhou Liu5Xiao Guo6Rui Zou7Yahong Wang8Dianfeng Sun9Lanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000, ChinaInstitute of Earthquake Forecasting, China Earthquake Administration, Beijing 100036, ChinaInstitute of Earthquake Forecasting, China Earthquake Administration, Beijing 100036, ChinaSchool of Resources and Safety Engineering, Chongqing University, Chongqing 400044, ChinaLanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000, ChinaLanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000, ChinaLanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000, ChinaLanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000, ChinaLanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000, ChinaLanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000, ChinaWe observed high-quality waves from a repeatable airgun seismic source recorded by a linear ultra-dense seismic array across the Xiliushui fault zone, one of the inactive faults in the Qilian Mountain, on the northeastern margin of the Tibetan Plateau, China. We used Snell’s law of seismic ray propagation to determine a simplified ambient velocity model. Based on the flexible and precise spectral element method, we computed broadband synthetic seismograms for a shallow low-velocity fault zone (FZ) to model the direct P-wave travel time delay and incident angle of the wavefield near the FZ. The FZ extent range and boundaries were inverted by apparent travel time delays and amplification patterns across the fault. According to prior information on the properties of the direct P-waves, we could constrain the inverse modeling and conduct a grid search for the fault parameters. The velocity reduction between the FZ and host rock, along with the dip angle of the FZ, were also constrained by the P-wave travel time delay systematic analysis and incoming angle of the P-waves. We found that the Xiliushui fault has a 70~80 m-wide low-velocity fault damage zone in which the P-wave velocity is reduced to ~40% with respect to the host rock. The fault damage zone dips ~35°southwest and extends to ~165 m in depth. The repeatability and environment protection characteristics of the airgun seismic survey and the economic benefits of a limited number of instruments setting are prominent.https://www.mdpi.com/2076-3263/15/1/16the fault zone seismic phaseairgun seismic sourcefault zone imagingbody waves modelingtravel time inversion |
| spellingShingle | Manzhong Qin Baichen Wu Yi Wang Xueyi Shang Yuansheng Zhang Xuzhou Liu Xiao Guo Rui Zou Yahong Wang Dianfeng Sun Imaging Shallow Velocity Structure of an Inactive Fault by Airgun Seismic Source: A Case Study of Xiliushui Fault in Qiliang Mountain Geosciences the fault zone seismic phase airgun seismic source fault zone imaging body waves modeling travel time inversion |
| title | Imaging Shallow Velocity Structure of an Inactive Fault by Airgun Seismic Source: A Case Study of Xiliushui Fault in Qiliang Mountain |
| title_full | Imaging Shallow Velocity Structure of an Inactive Fault by Airgun Seismic Source: A Case Study of Xiliushui Fault in Qiliang Mountain |
| title_fullStr | Imaging Shallow Velocity Structure of an Inactive Fault by Airgun Seismic Source: A Case Study of Xiliushui Fault in Qiliang Mountain |
| title_full_unstemmed | Imaging Shallow Velocity Structure of an Inactive Fault by Airgun Seismic Source: A Case Study of Xiliushui Fault in Qiliang Mountain |
| title_short | Imaging Shallow Velocity Structure of an Inactive Fault by Airgun Seismic Source: A Case Study of Xiliushui Fault in Qiliang Mountain |
| title_sort | imaging shallow velocity structure of an inactive fault by airgun seismic source a case study of xiliushui fault in qiliang mountain |
| topic | the fault zone seismic phase airgun seismic source fault zone imaging body waves modeling travel time inversion |
| url | https://www.mdpi.com/2076-3263/15/1/16 |
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