There is a massive amount of geomorphic evidence for active tectonics in the Longmen Shan at the eastern margin of the Tibetan plateau. We have surveyed some typical geomorphic markers including the Wenchuan-Maowen, B...There is a massive amount of geomorphic evidence for active tectonics in the Longmen Shan at the eastern margin of the Tibetan plateau. We have surveyed some typical geomorphic markers including the Wenchuan-Maowen, Beichuan-Yingxiu and Pengxian-Guanxian faults, terrace offsets, scarps, fault-controlled saddles, dextral shutter ridges, dextral channel offsets, graben, shatter belts, and pull-apart basins. Electron spin resonance （ESR） and thermoluminescence（TL） ages were obtained using silty sand taken from below the surface of the sediments. According to these data, we calculated the rates of thrusting and strike-slip, and the results indicate that Cenozoic tectonic shortening at the plateau margin is minor with the rate of thrusting less than 1.10 mm/a and the rate of strike-slipping less than 1.46 mm/a. The Longmen Shan is a zone of NNE-trending dextral shear with slip-dip ratio of 6：1-1.3：1. From NW to SE, the thrust component becomes smaller, whereas the strike-slip component becomes larger.展开更多
A seismic-geological disaster can obviously affect an engineering site in three aspects:the first is ground faulting caused by the earthquake;the second is strong ground motion;the third is geological disasters such a...A seismic-geological disaster can obviously affect an engineering site in three aspects:the first is ground faulting caused by the earthquake;the second is strong ground motion;the third is geological disasters such as landslides,mud-rock flows and liquefaction.Through the case study of selection of the huge transformer substation in the Shimian region of Sichuan Province,this paper proposes that the activity pattern and spatial distribution of faults near the site are crucial factors for evaluating the seismic-geological conditions for the location of huge transformer substations.展开更多
Fault structures in the Litang-Batang region of West Sichuan are mainly sub-longitudinal and a set of NNE- and NW-trending conjugate shear fracture zones is developed. In this paper, emphasis is put on explaining the ...Fault structures in the Litang-Batang region of West Sichuan are mainly sub-longitudinal and a set of NNE- and NW-trending conjugate shear fracture zones is developed. In this paper, emphasis is put on explaining the movement patterns along the fault structures in the region since the late Pleistocene-Holocene on the basis of detailed interpretation of TM satellite images and aero-photos in geomorphologic aspect of active structures. The sub-latitudinal shortening rate along the sub-longitudinal Jinshajiang fault zone is determined to be 2～3mm/a since the late Quaternary, the horizontal dextral slip movement rate along the NNE-trending Batang fault is 1.3～2.7mm/a on average, and the horizontal sinistral slip movement rate along the NW-trending Litang fault is 2.6～4.4 mm/a on average. The general status of the recent crustal movement in the region and the regularities of block motion caused by it are analyzed in combination with data of geophysical fields, focal mechanism solutions and GPS measurements. The occurrence of the 1989 Batang M6.2～6.7 earthquake swarm is suggested to be the result of tensional rupture along the sub-latitudinal normal fault derived from the conjugate shearing along the NNE-trending Batang and the NW-trending Litang faults. It reveals a typical seismic case produced by normal faulting in a compressional tectonic environment.展开更多
An earthquake with magnitude of 5.7 took place on Aug. 18, 2003 in the Nyingchi Region, Tibet. The macroseismic epicenter was located in the unpopniated high mountain area, 13 km south of Zhamo town, Bond County. The ...An earthquake with magnitude of 5.7 took place on Aug. 18, 2003 in the Nyingchi Region, Tibet. The macroseismic epicenter was located in the unpopniated high mountain area, 13 km south of Zhamo town, Bond County. The seismic intensity in the meizoseismal region was Ⅶ degree. The Ⅶ and Ⅵ areas were 2000 km^2 and 11000 km^2 , respectively. This seismic event is related to the movements of the Lhari fault trending in the NW direction and the ZhamoManiweng fault trending in the NE direction. As a result of this earthquakes, the buildings in the areas were badly damaged.展开更多
区别于经典的基于Parzen窗口法的概率密度函数估计器构建策略,提出了基于近邻误差度量函数的启发式核密度估计器(Heuristic kernel density estimator,HKDE),用以提升对模相近数据概率密度函数拟合的准确性。首次从数据不确定性和模型...区别于经典的基于Parzen窗口法的概率密度函数估计器构建策略,提出了基于近邻误差度量函数的启发式核密度估计器(Heuristic kernel density estimator,HKDE),用以提升对模相近数据概率密度函数拟合的准确性。首次从数据不确定性和模型不确定性的角度分析了传统核密度估计器解决模相近数据概率密度函数估计问题时的缺陷:利用概率密度值对于直方图箱宽参数的收敛性确定观测数据的启发式概率密度值,降低数据概率密度值计算的不确定性;基于启发式概率密度值构建用于确定核密度估计器最优带宽的目标函数,降低最优带宽优化过程中的不确定性。在18个模相近数据集上对新估计器HKDE的可行性、合理性和有效性进行了系统性的验证。实验结果表明,与7种具有代表性的概率密度函数估计器相比,HKDE能够获得更加优异的概率分布近似表现,具有比其他估计器更低的估计误差,能够确定出更接近真实值的概率密度函数估计值。展开更多
基金This research was supported by the National Nature Foundation of China （49803031, 40372084） the Seismic Scientific United Fund （95-07-0425）+3 种基金 US National Science Foundation grant EAR-0125565 ETH Forschungskommission grant TH-4/03-01 Key Subject Program of Sichuan province Grant No. SZD0408 and the Program for the Subject of Ph.D. in Higher Education Institute, Grant No.20050616004.
文摘There is a massive amount of geomorphic evidence for active tectonics in the Longmen Shan at the eastern margin of the Tibetan plateau. We have surveyed some typical geomorphic markers including the Wenchuan-Maowen, Beichuan-Yingxiu and Pengxian-Guanxian faults, terrace offsets, scarps, fault-controlled saddles, dextral shutter ridges, dextral channel offsets, graben, shatter belts, and pull-apart basins. Electron spin resonance （ESR） and thermoluminescence（TL） ages were obtained using silty sand taken from below the surface of the sediments. According to these data, we calculated the rates of thrusting and strike-slip, and the results indicate that Cenozoic tectonic shortening at the plateau margin is minor with the rate of thrusting less than 1.10 mm/a and the rate of strike-slipping less than 1.46 mm/a. The Longmen Shan is a zone of NNE-trending dextral shear with slip-dip ratio of 6：1-1.3：1. From NW to SE, the thrust component becomes smaller, whereas the strike-slip component becomes larger.
基金This project was sponsored by the National 973 Programme of China (4047109)
文摘A seismic-geological disaster can obviously affect an engineering site in three aspects:the first is ground faulting caused by the earthquake;the second is strong ground motion;the third is geological disasters such as landslides,mud-rock flows and liquefaction.Through the case study of selection of the huge transformer substation in the Shimian region of Sichuan Province,this paper proposes that the activity pattern and spatial distribution of faults near the site are crucial factors for evaluating the seismic-geological conditions for the location of huge transformer substations.
文摘Fault structures in the Litang-Batang region of West Sichuan are mainly sub-longitudinal and a set of NNE- and NW-trending conjugate shear fracture zones is developed. In this paper, emphasis is put on explaining the movement patterns along the fault structures in the region since the late Pleistocene-Holocene on the basis of detailed interpretation of TM satellite images and aero-photos in geomorphologic aspect of active structures. The sub-latitudinal shortening rate along the sub-longitudinal Jinshajiang fault zone is determined to be 2～3mm/a since the late Quaternary, the horizontal dextral slip movement rate along the NNE-trending Batang fault is 1.3～2.7mm/a on average, and the horizontal sinistral slip movement rate along the NW-trending Litang fault is 2.6～4.4 mm/a on average. The general status of the recent crustal movement in the region and the regularities of block motion caused by it are analyzed in combination with data of geophysical fields, focal mechanism solutions and GPS measurements. The occurrence of the 1989 Batang M6.2～6.7 earthquake swarm is suggested to be the result of tensional rupture along the sub-latitudinal normal fault derived from the conjugate shearing along the NNE-trending Batang and the NW-trending Litang faults. It reveals a typical seismic case produced by normal faulting in a compressional tectonic environment.
文摘An earthquake with magnitude of 5.7 took place on Aug. 18, 2003 in the Nyingchi Region, Tibet. The macroseismic epicenter was located in the unpopniated high mountain area, 13 km south of Zhamo town, Bond County. The seismic intensity in the meizoseismal region was Ⅶ degree. The Ⅶ and Ⅵ areas were 2000 km^2 and 11000 km^2 , respectively. This seismic event is related to the movements of the Lhari fault trending in the NW direction and the ZhamoManiweng fault trending in the NE direction. As a result of this earthquakes, the buildings in the areas were badly damaged.
文摘区别于经典的基于Parzen窗口法的概率密度函数估计器构建策略,提出了基于近邻误差度量函数的启发式核密度估计器(Heuristic kernel density estimator,HKDE),用以提升对模相近数据概率密度函数拟合的准确性。首次从数据不确定性和模型不确定性的角度分析了传统核密度估计器解决模相近数据概率密度函数估计问题时的缺陷:利用概率密度值对于直方图箱宽参数的收敛性确定观测数据的启发式概率密度值,降低数据概率密度值计算的不确定性;基于启发式概率密度值构建用于确定核密度估计器最优带宽的目标函数,降低最优带宽优化过程中的不确定性。在18个模相近数据集上对新估计器HKDE的可行性、合理性和有效性进行了系统性的验证。实验结果表明,与7种具有代表性的概率密度函数估计器相比,HKDE能够获得更加优异的概率分布近似表现,具有比其他估计器更低的估计误差,能够确定出更接近真实值的概率密度函数估计值。
