The Qilian-Haiyuan fault zone in the northeastern Tibetan Plateau has been the source of strong earthquakes in the region.In its middle segment,the Jinqianghe fault is an important active fault within the Tianzhu seis...The Qilian-Haiyuan fault zone in the northeastern Tibetan Plateau has been the source of strong earthquakes in the region.In its middle segment,the Jinqianghe fault is an important active fault within the Tianzhu seismic gap;however,little is known about its slip behavior.To present a new horizontal displacement distribution along this fault,we used WorldView-2 stereo pairs and unmanned aerial vehicle-based photogrammetry to construct digital elevation models to obtain a detailed tectono-geomorphic interpretation and geomorphic offsets.The offset marker measurements yielded 135 geomorphic displacements and 8 offset clusters.Radiocarbon dating was used to establish the regional age sequence of the geomorphic units in offset fluvial terraces at four study sites.The displacements and ages linked the offset clusters with the geomorphic unit sequence;the Holocene strike-slip rate of the Jinqianghe fault was estimated to 4.8-5.6 mm/a at~4-12 ka and 2.9-4.7 mm/a from~4 ka.Three recent earthquakes(with a recurrence interval of~1000 years)represent an active seismic period,revealing the potential seismic hazard along this fault because it has not ruptured in the last 1500 years.展开更多
On January 21, 2016, a strong earthquake with a magnitude of Ms6.4 occurred at Menyuan, Qinghai Province of China. In almost the same region, there was another strong earthquake happened in 1986, with similar magnitud...On January 21, 2016, a strong earthquake with a magnitude of Ms6.4 occurred at Menyuan, Qinghai Province of China. In almost the same region, there was another strong earthquake happened in 1986, with similar magnitude and focal mechanism. Based on comprehensive analysis of regional active faults, focal mechanism solutions, precise locations of aftershocks, as well as GPS crustal deformation, we inferred that the Lenglongiing active fault dips NE rather than SW as suggested by previous studies. Considering the facts that the 2016 and i986 Ms6.4 Menyuan earthquakes are closely located with similar focal mechanisms, both of the quakes are on the north side of the Lenglongling Fault and adjacent to the fault, and the fault is dipping NE direction, we suggest that the fault should be the seismogenic structure of the two events. The Lenglongling Fault, as the western segment of the well-known Tianzhu seismic gap in the Qilian-Haiyuan active fault system, is in a relatively active state with frequent earthquakes in recent years, implying a high level of strain accumulation and a high potential of major event. It is also possible that the Lengiongiing Fault and its adjacent fault, the Jinqianghe Fault in the Tianzhu seismic gap, are rupturing simultaneously in the future.展开更多
1研究背景祁连-海原断裂带作为青藏高原东北缘边界带的一条大型走滑断裂带,不仅控制着青藏高原东北缘地区的几何和构造格局,而且在调节东北缘地壳物质相对于阿拉善地块的向东运动中起到重要作用,断裂以左旋走滑为主,全长约1000 km,由西...1研究背景祁连-海原断裂带作为青藏高原东北缘边界带的一条大型走滑断裂带,不仅控制着青藏高原东北缘地区的几何和构造格局,而且在调节东北缘地壳物质相对于阿拉善地块的向东运动中起到重要作用,断裂以左旋走滑为主,全长约1000 km,由西向东主要由托莱山断裂、冷龙岭断裂、金强河断裂、毛毛山断裂、老虎山断裂和海原断裂组成(Tapponnier et al,1976,2001;Peltzer et al,1988;Zhang et al,1991;Gaudemer et al,1995;Zheng et al,2013;Daout et al,2016)。断裂现今地震活动性较强,据历史资料记载,自1900年以来,在祁连-海原断裂带上发生多次中强地震,如1920年海原8½级、1986年门源M_(S) 6.4、1990年天祝-景泰M_(S) 6.2、2016年门源M_(S) 6.4等地震,2022年1月8日青海门源M_(S) 6.9地震也发生在托莱山和冷龙岭断裂上(李振洪等,2022;Yang et al,2022)(图1)。展开更多
基金This work was supported by the National Key Research and Development Program of China(Grant No.2017YFC1500100)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0901)+1 种基金the National Science Foundation of China(Grant Nos.41774049,41972228,41874020)the Guangdong Province Introduced Innovative R&D Team of Geological Processes and Natural Disasters around the South China Sea(Grant No.2016ZT06N331).
文摘The Qilian-Haiyuan fault zone in the northeastern Tibetan Plateau has been the source of strong earthquakes in the region.In its middle segment,the Jinqianghe fault is an important active fault within the Tianzhu seismic gap;however,little is known about its slip behavior.To present a new horizontal displacement distribution along this fault,we used WorldView-2 stereo pairs and unmanned aerial vehicle-based photogrammetry to construct digital elevation models to obtain a detailed tectono-geomorphic interpretation and geomorphic offsets.The offset marker measurements yielded 135 geomorphic displacements and 8 offset clusters.Radiocarbon dating was used to establish the regional age sequence of the geomorphic units in offset fluvial terraces at four study sites.The displacements and ages linked the offset clusters with the geomorphic unit sequence;the Holocene strike-slip rate of the Jinqianghe fault was estimated to 4.8-5.6 mm/a at~4-12 ka and 2.9-4.7 mm/a from~4 ka.Three recent earthquakes(with a recurrence interval of~1000 years)represent an active seismic period,revealing the potential seismic hazard along this fault because it has not ruptured in the last 1500 years.
基金supported by the Na-tional Science Foundation of China(41474090)the State Key Laboratory of Earthquake Dynamics(LED 2013A02)
文摘On January 21, 2016, a strong earthquake with a magnitude of Ms6.4 occurred at Menyuan, Qinghai Province of China. In almost the same region, there was another strong earthquake happened in 1986, with similar magnitude and focal mechanism. Based on comprehensive analysis of regional active faults, focal mechanism solutions, precise locations of aftershocks, as well as GPS crustal deformation, we inferred that the Lenglongiing active fault dips NE rather than SW as suggested by previous studies. Considering the facts that the 2016 and i986 Ms6.4 Menyuan earthquakes are closely located with similar focal mechanisms, both of the quakes are on the north side of the Lenglongling Fault and adjacent to the fault, and the fault is dipping NE direction, we suggest that the fault should be the seismogenic structure of the two events. The Lenglongling Fault, as the western segment of the well-known Tianzhu seismic gap in the Qilian-Haiyuan active fault system, is in a relatively active state with frequent earthquakes in recent years, implying a high level of strain accumulation and a high potential of major event. It is also possible that the Lengiongiing Fault and its adjacent fault, the Jinqianghe Fault in the Tianzhu seismic gap, are rupturing simultaneously in the future.
文摘1研究背景祁连-海原断裂带作为青藏高原东北缘边界带的一条大型走滑断裂带,不仅控制着青藏高原东北缘地区的几何和构造格局,而且在调节东北缘地壳物质相对于阿拉善地块的向东运动中起到重要作用,断裂以左旋走滑为主,全长约1000 km,由西向东主要由托莱山断裂、冷龙岭断裂、金强河断裂、毛毛山断裂、老虎山断裂和海原断裂组成(Tapponnier et al,1976,2001;Peltzer et al,1988;Zhang et al,1991;Gaudemer et al,1995;Zheng et al,2013;Daout et al,2016)。断裂现今地震活动性较强,据历史资料记载,自1900年以来,在祁连-海原断裂带上发生多次中强地震,如1920年海原8½级、1986年门源M_(S) 6.4、1990年天祝-景泰M_(S) 6.2、2016年门源M_(S) 6.4等地震,2022年1月8日青海门源M_(S) 6.9地震也发生在托莱山和冷龙岭断裂上(李振洪等,2022;Yang et al,2022)(图1)。
