Dizhi lixue xuebao (Apr 2024)
Late Quateranry paleoseismicity of the Xitieshan-Amunikeshan section of the northern margin fault of the Qaidam Basin
Abstract
Objective The northern margin fault zone of the Qaidam Basin is a regional active fault zone in the northern part of the Qinghai-Tibet Plateau, forming the boundary fault of the northern Qaidam Basin and the Qilian Mountains. Studying its late Quaternary paleoseismic activity is of great significance for understanding the seismic recurrence cycle and seismic hazard of the northern margin fault zone of the Qaidam Basin. Methods Through geological survey, remote sensing interpretation, trench excavation, OSL geological dating, and analysis of paleoseismic events, the paleoseismic events of the northern margin fault of the Qaidam Basin (Xitieshan-Amunikeshan section) were studied. Conclusion The study reveals that the trench profiles exposed five relatively reliable paleoseismic events, with occurrence times of approximately 60 years ago for Event E1, 3.1±0.3 to 3.4±0.3 ka for Event E2, 7.5±0.3 to 8.1±0.3 ka for Event E3, 10.1±0.4 to 11.4±0.4 ka for Event E4, and 12.1±0.4 to 12.8±0.4 ka for Event E5. Using the paleoseismic incremental limiting method, the seismic recurrence cycle of the northern margin fault of the Qaidam Basin (Xitieshan-Amunikeshan section) is estimated to be 2.6 to 3.4 ka. The most recent event departure time for the Amunikeshan section is 60 years ago, and for the Xitieshan section, it is 3.1±0.3 ka, suggesting a higher likelihood of destructive earthquakes in the future for the Xitieshan section compared to the Amunikeshan section of the northern margin fault of the Qaidam Basin. Significance This result can provide a better understanding of the paleoseismic events, recurrence intervals, and other aspects of the northern margin fault of the Qaidam Basin, which has guiding significance for seismic forecasting, prediction, and evaluation of future seismic hazards of this fault.
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