汶川MS8.0地震断层映秀—南坝段的活动方式、形变特征及其形成机制

通过对2008年5月12日发生的汶川8.0级地震的发震构造——中央断裂映秀—南坝段地震地表破裂、地表形变及断裂上余震迁移等特征的详细调查和分析,结果表明：（1）自映秀至南坝,断层活动方式表现为由逆冲逐渐过渡为逆冲-右旋走滑、再到走滑分量与逆冲分量大致相当,同时断层两盘滑动伴有相对弱旋转活动;（2）在断层总体走向NE向、逆冲为主兼右旋走滑活动方式下,局部表现为走向NW向、逆冲为主兼左旋走滑活动方式;（3）地震裂缝与单侧破裂面关系,以及地表重叠缩短形变特征表明,断层活动、应变能释放是在近EW向区域构造应力及NE向局部构造应力综合作用下的结果.依据断层沿线地表裂缝产状的变化,粗略推出映秀至南坝段主应力方向由SEE向NEE方向变化,与前人使用CAP（Cut and Pasate）方法求出的主余震源机制方向基本一致.     

Effects of landuse change on surface runoff and sediment yield at different watershed scales on the Loess Plateau

Erosion and sediment yield from large and small watersheds exhibit different laws. Variations in surface runoff and sediment yield because of landuse change in four watersheds of different scales from 1 km2 to 73 km2 were analyzed. Due to reforestation and farmland terracing, surface runoff and sediment yield reduced by 20-100% and 10-100% respectively. Reductions in surface runoff were differed significantly under different precipitation regimes. For the large watershed (73 km2) landuse change had similar effects on surface runoff regardless of changing of precipitation. For the small watershed (1 km2) landuse change had fewer effects on surface runoff under high precipitation. The relative changes of sediment yield in the four watersheds under reforestation and farmland terracing decreased as precipitation increased from 350 mm to 650 mm, then increased as precipitation increased from 650 mm to 870 mm. Where initial forest coverage rate was below 45%, sediment yield decreased dramatically as forest coverage rate increased. Watershed management with aiming at reducing both surface runoff and sediment yield should be conducted both on sloping surfaces and in channels in large watersheds.     

Assessment of uncertainty sources in water quality modeling in the Niagara River

This paper presents a framework to quantify the overall variability of the model estimations of Total Polychlorinated Biphenyls (Total PCBs) concentrations in the Niagara River on the basis of the uncertainty of few model parameters and the natural variability embedded in some of the model input variables. The results of the uncertainty analysis are used to understand the importance of stochastic model components and their effect on the overall reliability of the model output and to evaluate multiple sources of uncertainty that might need to be further studied. The uncertainty analysis is performed using a newly developed point estimate method, the Modified Rosenblueth method. The water quality along the Niagara River is simulated by coupling two numerical models the Environmental Fluid Dynamic Code (EFDC) – for the hydrodynamic portion of the study and the Water Quality Analysis and Simulation Program (WASP) – for the fate and transport of contaminants. For the monitoring period from May 1995 to March 1997, the inflow Total PCBs concentration from Lake Erie is the stochastic component that most influences the variability of the modeling results for the simulated concentrations at the exit of the Niagara River. Other significant stochastic components in order are as follows: the suspended sediments concentration, the point source loadings and to a minor degree the atmospheric deposition, the flow and the non-point source loadings. Model results that include estimates of uncertainty provide more comprehensive information about the variability of contaminant concentrations, such as confidence intervals, and, in general offer a better approach to compare model results with measured data.     

用微动中的面波信息探测地壳浅部的速度结构

本文介绍了利用地脉动中的面波信息探测地壳浅部横波速度结构的观测方法、仪器设备、野外数据采集和用空间自相关方法测定相速度及相关的数据处理方法,并给出了在两个场地的探测实例. 通过与钻探结果对比表明,由该方法推测的地壳浅部1～2 km 深度范围的浅层横波速度结构,对于确定物性差异大的地层界面是有效和可靠的. 由于该方法使用的是地脉动噪声中的面波信息,不需要专门的震源, 因此具有经济快捷、应用范围广泛等优点,将可能成为一种新的具有很好应用前景的地球物理勘探方法.     

汶川8.0级地震滑坡、崩塌机制

本文总结了汶川8．0级地震引起的滑坡、崩塌的破坏特征,分析了地震地质灾害的外因和内因。鉴于本次地震导致的大量人员伤亡和巨大的财产损失,在进行城镇灾后重建工作或类似山区城镇规划时,强烈建议进行地震地质灾害评估工作。     

Shear velocity structure of crust and uppermost mantle in China from surface wave tomography using ambient noise and earthquake data

We present a 3D model of shear velocity of crust and upper mantle in China and surrounding regions from surface wave tomography.We combine dispersion measurements from ambient noise correlation and traditional earthquake data.The stations include the China National Seismic Network,global networks,and all the available PASSCAL stations in the region over the years.The combined data sets provide excellent data coverage of the region for surface wave measurements from 8 to 120 s,which are used to invert for 3D shear wave velocity structure of the crust and upper mantle down to about150 km.We also derive new models of the study region for crustal thickness and averaged S velocities for upper,mid,and lower crust and the uppermost mantle.The models provide a fundamental data set for understanding continental dynamics and evolution.The tomography results reveal significant features of crust and upper mantle structure,including major basins,Moho depth variation,mantle velocity contrast between eastern and western North China Craton,widespread low-velocity zone in midcrust in much of the Tibetan Plateau,and clear velocity contrasts of the mantle lithosphere between north and southern Tibet with significant E–W variations.The low velocity structure in the upper mantle under north and eastern TP correlates with surface geological boundaries.A patch of high velocity anomaly is found under the eastern part of the TP,which may indicate intact mantle lithosphere.Mantle lithosphere shows striking systematic change from the western to eastern North China Craton.The Tanlu Fault appears to be a major lithosphere boundary.     

地震地表破裂发育特点及环境条件分析

通过已有震害实例分析，总结出了地震地表破裂的发育特点，在此基础上，结合震源破裂的深、浅部环境条件和形成力学机制、震源破裂和地震地表破裂的相互关系，讨论了地震地表破裂形成的环境条件。认为其所处的地震地质区特点是影响地震地表破裂发育的宏观环境条件，而场地第四系松散地层是影响地震地表破裂发育的微观环境条件。第四系地层对地震地表破裂的影响主要取决于第四系地层的土动力学性状、不均匀性和土层厚度等因素。     

Fe(Ⅱ)/铁氧化物表面结合铁系统还原有机污染物的研究进展

在土壤和沉积物的自然厌氧环境中,铁氧化物可被铁还原菌等微生物异化还原产生Fe(Ⅱ),形成的Fe(Ⅱ)/铁氧化物表面结合铁系统具有还原活性,可使有机污染物还原转化。综述了含卤和含硝基有机污染物的非生物还原转化过程和表面结合铁系统与有机污染物之间的界面反应机理,进而揭示了污染物在环境中的赋存状态和迁移转化规律;重点分析了影响该还原过程的因素,如铁氧化物类型、pH值、Fe(Ⅱ)与铁氧化物接触时间,以及过渡金属、腐殖酸等竞争因子对反应过程的影响。强化自然界中天然的Fe(Ⅱ)/铁氧化物表面结合铁系统在有机污染治理中的作用,在受污染环境修复领域具有广阔的应用前景。 [HT5H]关 键 词:[HT5K]     

2007年8月大连地区一次暴雨过程特征分析

运用常规天气图资料,并根据地面自动站和多普勒雷达等资料,综合分析了2007年8月10－12日大连地区暴雨天气过程。结果表明：地面中尺度气旋的生成和发展是产生大暴雨的动力条件,低空急流的建立为暴雨产生提供了大量水汽,稳定的高压坝是暴雨落区在大连出现的必要前提。