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On August 8, 2017, a Ms 7.0 earthquake occurred 5 km to the west of Jiuzhaigou National Park, causing 25 deaths and injuring 525. The objective of this study was to explore the seismogenic fault of the earthquake and tectonic dynamics of the source rupture. Field investigations, radon activity tests, remote sensing interpretations, and geophysical data analyses were carried out immediately after the earthquake. The Jiuzhaigou earthquake occurred at the intersection of the northern margin of the Minshan uplift belt and the south part of the Wenxian–Maqin fault in the south margin of the West Qinling geosyncline. There are two surface rupture zones trending northwest (NW), which are ground coseismic ruptures caused by concealed earthquake faults. The rupture on the southwest is the structure triggering the earthquake, along the Jiuzhaitiantang–Epicenter–Wuhuahai. The other one on the northeast (Shangsizhai–Zhongcha–Bimang) is a reactivation and extension of the secondary fault trending NW. The source rupture of this earthquake is a strike-slip shear fracture associated with the fault plane trending NW 331° and steeply dipping 75°, which is continuously expanding at both ends. The tectonic dynamics process of the source rupture is that the “Jiuzhaigou protrusion” is left-lateral sheared along the seismogenic fault in the NW direction. Finally, the Maqin fault and the arc fault system at the top of the “Wenxian protrusion” will be gradually broken through sometime in far future, as well as earthquaketriggered landslides will be further occurred along the narrow corridor between the seismogenic faults. The research results revealed the basic geological data and tectonic dynamic mechanism in this earthquake. 相似文献
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对山东半岛北部蓬莱林格庄黄土剖面进行了系统的野外考察,并进行了光释光测年以及粒度、磁化率指标分析。研究表明,磁化率的变化与不同粒级的百分含量具有一定的相关性,频率磁化率与粗颗粒含量基本呈一定的负相关。结合野外地层划分与光释光年代学测试可以将该剖面划分为3个黄土层和3个古土壤层,该剖面记录了末次间冰期以来该区气候和环境变化的历史。 相似文献
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目的: 探讨64排螺旋CT对症状性颈动脉狭窄的诊断价值。资料与方法: 搜集2008年12月至2011年3月期间在河南省人民医院神经内科住院的128例缺血性脑血管病患者(实验组)和75例非缺血性脑血管病患者(对照组)影像学资料。所有患者均接受64排螺旋CT血管成像检查,评估双侧颈动脉(颈总动脉、颈内动脉)斑块类型以及狭窄程度。结果: 实验组患者大多数均存在不同程度的颈动脉硬化斑块形成,实验组患者各段血管斑块类型以软斑为主,对照组患者硬斑数量明显高于软斑和混合斑;实验组患者颈动脉狭窄发生率(77.3%)明显高于对照组(33.3%),两者差异有统计学意义(P<0.01)。实验组患者左颈内动脉狭窄最多见,共35例,其次分别为右颈内动脉、左颈总动脉和右颈总动脉,分别为31例、19例和14例。结论: 64排螺旋CT不但能判定动脉内斑块数量和性质,而且可以评估血管狭窄程度及闭塞情况,在症状性颈动脉狭窄的诊断方面有着重要的应用价值。 相似文献
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徐树建 《地理与地理信息科学》2002,18(2):80-84
该文分析了西北地区生态退化的现状及原因 ,根据恢复生态学、可持续发展原理和生态经济学理论提出了西北地区生态恢复的原则和对策 相似文献
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山东庙岛群岛黄土的粒度特征及其环境意义 总被引:2,自引:0,他引:2
对山东庙岛群岛长岛黄土粒度的精细研究证明,滨海黄土是在第四纪冰期寒冷气候下的产物,末次冰期沉积的长岛剖面由风成沉积与冲-洪积层组成,末次冰期的风成沉积反映了末次冰期气候的不稳定性,其中存在6次气候变冷、渤海湾海面下降和6次气候变暖、渤海湾海面上升的事件,黄土的粒度中包含了丰富的气候变化和渤海湾海面变化的信息。 相似文献
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