1 INTRODUCTION As one of the main factors affecting input and use of precipitation by forests, rainfall also makes a difference on partitioning of gross precipitation over the canopy, equilibrium of water amount in ri...1 INTRODUCTION As one of the main factors affecting input and use of precipitation by forests, rainfall also makes a difference on partitioning of gross precipitation over the canopy, equilibrium of water amount in river basins and water cycling processes . In view of its poorlydefined four seasons in contrast to well-defined dry and wet spells in addition to its inland location, understanding of precipitation characteristics and tendencies is important for the study on local forestry hydrology. Relevant research has been documented, but few have dealt with multiple time scales at the hourly, daily, monthly and annual intervals. With the 1992 - 2003 automatic record of precipitation in Menglun, Xishuangbannan analyzed, its characteristics and trends are summarized to help in the study on forestry hydrology.展开更多
Deep-seated large-scale toppling failure presents unique challenges in the study of natural slope deformation process in mountainous regions.An active deep-seated toppling process was identified in the Erguxi slope lo...Deep-seated large-scale toppling failure presents unique challenges in the study of natural slope deformation process in mountainous regions.An active deep-seated toppling process was identified in the Erguxi slope located in southwest China,which affected a large area and damaged critical transportation infrastructure with the volume of the deforming rock mass exceeding 24×10~6 m^3.It poses significant risks to the downstream Shiziping Hydropower Station by damming the Zagunao River.Field investigation and monitoring results indicate that the deformation of the Erguxi slope is in the advanced stage of deep-seated toppling process,with the formation of a disturbed belt but no identifiable master failure surface.It was postulated that the alternating tensile and shear strength associated with the hard/soft laminated rock strata of metasandstone and phyllite layers preclude the development of either a tensile or shear failure surface,which resulted in the continuous deformation and displacement without a catastrophic mass movement.The slope movement is in close association with the unfavorable geological conditions of the study area in addition to the construction of transportation infrastructure and the increase of the reservoir level.On the basis of the mechanism and intensity of the ongoing toppling deformation,a qualitative grading system was proposed to describe the toppling process and toevaluate the slope stability.This paper summarized the field observation and monitoring data on the toppling deformation for better characterizing its effect on the stability of the Erguxi slope.The qualitative grading system intends to provide a basis for quantitative study of large-scale deep-seated toppling process in metamorphic rocks.展开更多
Abnormal disturbances, s uch as sharp pulses, w ere observed by vertical pendulum tiltmeters in Wudu, Hanzhong and Ningshaan seismic stations on August 6, 2008.According to the time and spatial location of the anomali...Abnormal disturbances, s uch as sharp pulses, w ere observed by vertical pendulum tiltmeters in Wudu, Hanzhong and Ningshaan seismic stations on August 6, 2008.According to the time and spatial location of the anomalies,we build a"source precursor"propagator to calculate possible focal region by aid of quasi-Newton least squares and grid search methods. The calculated focal region is located at the aftershock area of the Wenchuan earthquake on the northern section of Longmenshan fault zone,which may be related to the 54km-away M S5. 0 Pingwu-Beichuan earthquake,with starting time of about thirty three hours before the earthquake.展开更多
Based on the analyses of grouped activity features of deep-focus (M≥6.0) and shallow-focus (M S≥5.0) earthquakes in the Northeast China region, the time-space correlation between deep focus “strong earthquake group...Based on the analyses of grouped activity features of deep-focus (M≥6.0) and shallow-focus (M S≥5.0) earthquakes in the Northeast China region, the time-space correlation between deep focus “strong earthquake group" and shallow focus “strong earthquake group" have been studied. The study was mainly on the characteristics of earthquake distribution on the collision zone between the west Pacific plate and the Eurasian plate and on its relations to the morphological feature of the western Pacific subduction zone. Moreover, emphasis was laid on analysis of the effect of the west Pacific plate on the seismicity of Eurasian plate. It is shown that in the region where the west Pacific plate subducts at low angles, the seismicity on the plate collision zone is strong, the effect of plate subduction on Eurasian continent is strong too, and the subduction zone is under a state of high compressional stress. However, in the region where the west Pacific plate subducts at high angles, the seismicity along the plate collision zone is weak, the effect of plate subduction on Eurasian continent is weak too, and the tensile stress produced by the subduction zone at depth is enhanced. We therefore propose that the seismicity in the northeast China region will enter an active period of shallow “strong earthquake group" in the future 10 years. In the period, six earthquakes of M S≥5.0 may occur. Therefore, the work of earthquake monitoring and prediction in this region shall be strengthened.展开更多
基金Development Plan for Key National Foundation Research (Project 973 and 2003CB415100)Natural Science Foundation of Yunnan Province (2003C0002Z)
文摘1 INTRODUCTION As one of the main factors affecting input and use of precipitation by forests, rainfall also makes a difference on partitioning of gross precipitation over the canopy, equilibrium of water amount in river basins and water cycling processes . In view of its poorlydefined four seasons in contrast to well-defined dry and wet spells in addition to its inland location, understanding of precipitation characteristics and tendencies is important for the study on local forestry hydrology. Relevant research has been documented, but few have dealt with multiple time scales at the hourly, daily, monthly and annual intervals. With the 1992 - 2003 automatic record of precipitation in Menglun, Xishuangbannan analyzed, its characteristics and trends are summarized to help in the study on forestry hydrology.
基金financially supported by the National Natural Science Foundation of China (Grant No.41572302 and Grant No.41130745)the Funds for Creative Research Groups of China (Grant No.41521002)the Open Research Fund from the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Chengdu University of Technology) (Grant No.SKLGP2015K001)
文摘Deep-seated large-scale toppling failure presents unique challenges in the study of natural slope deformation process in mountainous regions.An active deep-seated toppling process was identified in the Erguxi slope located in southwest China,which affected a large area and damaged critical transportation infrastructure with the volume of the deforming rock mass exceeding 24×10~6 m^3.It poses significant risks to the downstream Shiziping Hydropower Station by damming the Zagunao River.Field investigation and monitoring results indicate that the deformation of the Erguxi slope is in the advanced stage of deep-seated toppling process,with the formation of a disturbed belt but no identifiable master failure surface.It was postulated that the alternating tensile and shear strength associated with the hard/soft laminated rock strata of metasandstone and phyllite layers preclude the development of either a tensile or shear failure surface,which resulted in the continuous deformation and displacement without a catastrophic mass movement.The slope movement is in close association with the unfavorable geological conditions of the study area in addition to the construction of transportation infrastructure and the increase of the reservoir level.On the basis of the mechanism and intensity of the ongoing toppling deformation,a qualitative grading system was proposed to describe the toppling process and toevaluate the slope stability.This paper summarized the field observation and monitoring data on the toppling deformation for better characterizing its effect on the stability of the Erguxi slope.The qualitative grading system intends to provide a basis for quantitative study of large-scale deep-seated toppling process in metamorphic rocks.
基金funded by the Shaanxi Natural Science Foundation as a Subproject of the Project Entitled "Research on Origin of the Large-amplitude Deformation Anomaly in Hancheng and Qianxian Seismic Stations and the Seismic Hazard of Strong Earthquake in the Guanzhong Region"(2014JM2-4039)
文摘Abnormal disturbances, s uch as sharp pulses, w ere observed by vertical pendulum tiltmeters in Wudu, Hanzhong and Ningshaan seismic stations on August 6, 2008.According to the time and spatial location of the anomalies,we build a"source precursor"propagator to calculate possible focal region by aid of quasi-Newton least squares and grid search methods. The calculated focal region is located at the aftershock area of the Wenchuan earthquake on the northern section of Longmenshan fault zone,which may be related to the 54km-away M S5. 0 Pingwu-Beichuan earthquake,with starting time of about thirty three hours before the earthquake.
文摘Based on the analyses of grouped activity features of deep-focus (M≥6.0) and shallow-focus (M S≥5.0) earthquakes in the Northeast China region, the time-space correlation between deep focus “strong earthquake group" and shallow focus “strong earthquake group" have been studied. The study was mainly on the characteristics of earthquake distribution on the collision zone between the west Pacific plate and the Eurasian plate and on its relations to the morphological feature of the western Pacific subduction zone. Moreover, emphasis was laid on analysis of the effect of the west Pacific plate on the seismicity of Eurasian plate. It is shown that in the region where the west Pacific plate subducts at low angles, the seismicity on the plate collision zone is strong, the effect of plate subduction on Eurasian continent is strong too, and the subduction zone is under a state of high compressional stress. However, in the region where the west Pacific plate subducts at high angles, the seismicity along the plate collision zone is weak, the effect of plate subduction on Eurasian continent is weak too, and the tensile stress produced by the subduction zone at depth is enhanced. We therefore propose that the seismicity in the northeast China region will enter an active period of shallow “strong earthquake group" in the future 10 years. In the period, six earthquakes of M S≥5.0 may occur. Therefore, the work of earthquake monitoring and prediction in this region shall be strengthened.
