Determination of regional stress tensors from fault-slip data   总被引：1，自引：0，他引：1  

Peiliang Xu 《Geophysical Journal International》2004,157(3):1316-1330

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How are storm time injections different from nonstorm time injections?     

D.-Y. Lee  J.A. Hwang  E.S. Lee  K.W. Min  W.Y. Han  U.W. Nam 《Journal of Atmospheric and Solar》2004,66(18):1715

One of the key elements of storms and substorms is the injection of energetic particles into the region of near geosynchronous orbit, that is, the sudden flux enhancement in the energy range of tens to hundreds of keV. This paper reports the observational results on how such injection features during storm times are different from those of nonstorm times. We particularly focus on the difference between proton injections and electron injections. Based on a number of storm time injection events that meet our strict selection criteria, we find a notable difference between proton injections and electron injections in the energy-spectral dependence of the flux enhancement averaged over the first 30 min after the injection onset: The average flux enhancement of many protons injections tends to be bigger at higher energy channels than at lower energy channels, but electron injections exhibit the opposite tendency for the energy-spectral dependence of flux enhancement, i.e., average flux enhancement decreasing with increasing energy. We show that this feature is almost unique only for the injection events during the storm main and early recovery phase. It is suggested that any successful scenario intended to model storm time injections should be able to explain this difference between proton injections and electron injections.  相似文献   

交互式洪水预报系统及关键技术研究   总被引：5，自引：0，他引：5  

刘金平  张建云 《水文》2004,24(1):4-9

介绍了交互式洪水预报系统的概念和基本结构，分析了实现交互式预报的区域拓扑连接、作业表、模型参数优化、交互修正等关键技术，并以淮河交互式洪水预报系统为例，阐述了系统的组成、实时作业预报的数据流程和应用成果。在分析我国暴雨洪水特性和自然地理条件的基础上，指出了在我国开发交互式洪水预报系统的必要性和应该注意的几个主要问题。  相似文献   

秦昆结合区两期基性岩墙群^40Ar／^39Ar定年及其构造意义   总被引：11，自引：1，他引：11       下载免费PDF全文

孙延贵  张国伟王瑾詹发余  张智勇 《地质学报》2004,78(1):65-71

秦昆(秦岭-昆仑)结合区在不同地质背景基础上于柴达木东缘次级造山带南东段的拉龙洼和满丈岗地区发育了两期基性岩墙群,~(40)Ar/~(39)Ar定年结果分别为393.5Ma和197.5Ma,它们分别代表着东古特提斯洋北支及其北侧秦昆间共和坳拉谷的初始伸展离散和这一构造系统封闭碰撞造山后的伸展垮塌构造岩浆事件。结合区域资料进一步分析表明,晚古生代中晚期东昆南-阿尼玛卿和阿尼玛卿-文县-勉略两支裂谷发育成相互沟通的东古特提斯洋北支时,苦海-赛什塘一支发生“夭折”而形成共和坳拉谷,这一构造系统于三叠纪晚期各区段几乎是同时发生收缩、闭合、碰撞造山,东昆南-阿尼玛卿-文县-勉略有限洋盆的向北俯冲碰撞造山形成统一的秦昆造山带,共和坳拉谷的封闭使西秦岭与东昆仑完成了侧向间的衔接。本文的研究给这一秦昆衔接的动力学演化过程提供了时代依据。  相似文献   

Size-Resolved Aerosol Characterization for a Polluted Episode at the IfT Research Station Melpitz in Autumn 1997     

A. Plewka  T. Gnauk  E. Brüggemann  C. Neusüss  H. Herrmann 《Journal of Atmospheric Chemistry》2004,48(2):131-156

Inorganic ions, organic carbon (OC), elemental carbon (EC) and a variety of organic single species in airborne particles have been determined at the research station of the Leibniz – Institut für Troposphärenforschung (IfT) in Melpitz (Germany) in autumn 1997.Samples of eight selected measurement events were divided in two groups in order to investigate differences in the chemical composition of particles originating from southwesterly (SW – developed EU countries) or from easterly directions (E – less developed eastern countries). Differences between these two groups were tested statistically by Student's t-test.Five stage cascade impactor samples show nitrate as most abundant in the accumulation mode in the SW group. EC and sulphate show the most abundant mass fractions in the E group. That can be considered as a consequence of domestic coal heating and coal-fired power plant emissions in the region of westerly Poland, northern Czech Republic and easterly Germany. Higher nitrate concentrations in the SW group can be explained by stronger NO _x emissions caused by the leeward plume of the conurbation of Leipzig, as well as by the still higher traffic density in western Germany.The methane sulphonic acid (MSA) mass fraction was higher for SW air masses in accumulation mode particles, probably indicating marine origin. Succinic acid also showed higher mass fractions for the SW group. This could be caused by primary emission in automobile exhaust gases and photochemical formation during transport from SW. Indeed, during SW sampling, solar radiation intensity was higher than during E sampling.The observed differences in the particle composition are an expression of the still existing technology gradient in Europe. Future campaigns could show the development to a joint economy with smaller differences in anthropogenic emissions.  相似文献   

Particle clusters in gravel‐bed rivers: an experimental morphological approach to bed material transport and stability concepts     

Lea Wittenberg  Malcolm D. Newson 《地球表面变化过程与地形》2005,30(11):1351-1368

Structured gravel river beds clearly exert a major influence on bed stability. Indexing structural stability by field measurements of bed strength neglects the processes operating to entrain and transport bed material in different parts of each structure. This study takes a morphological approach to interpreting the critical processes, using particle tracing to determine the movement of individual cluster particles over a range of flood event magnitudes and durations. The experiment was carried out on the River South Tyne, UK; it uses flow hydrographs measured nearby and also benefits from previous studies of historical development, channel morphology and sediment transport at the same site. More than 30 clusters were monitored over a seven‐month period during which clusters occupied 7–16 per cent of the bed. Threshold flows delimiting three apparently contrasting bed sediment process regimes for cluster particles are tentatively set at 100 m³ s^?1 and 183 m³ s^?1; durations of flow at these levels are critical for cluster development, rather than flow peak values. Wake particles are transported most easily. Flow straightening in the wandering channel planform reduces the stability of clusters, since mechanical strength is markedly reduced by this change of direction. The overall area covered by clusters between significant transport events varies little, implying a dynamic equilibrium condition. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

地质雷达资料的偏移速度分析和叠前偏移   总被引：2，自引：1，他引：2  

周辉  韩波  邱东玲  裴建新  王兆磊 《吉林大学学报(地球科学版)》2005,35(2):248-252,256

地质雷达资料偏移成像的精度与地下介质介电常数分布的确定精度有直接关系.提出用全局最优化偏移速度分析方法求取介电常数分布.目标函数定义为各共成像点道集零延迟归一化互相关值之和.在假设地下介质是分块的,且每块介质的介电常数可以用有限项的与空间坐标有关的多项式函数来表示的前提下,用遗传算法由浅至深逐块确定使目标函数达到最大的多项式函数的各项系数从而确定介电常数.叠前偏移用时间域有限差分求解麦克斯韦方程组的逆时偏移方法实现.合成雷达记录的偏移速度分析和偏移叠加结果表明,全局最优化偏移速度分析有较高的精度,偏移叠加剖面与实际构造一致.  相似文献   

Timing of remanent magnetization acquisition in red beds: A case study from a syn-folding sedimentary basin     

Koji Uno  Kuniyuki Furukawa 《Tectonophysics》2005,406(1-2):67-80

We propose to explain the origin of the double trend in seismicity of the Macas swarm in the Subandean Cordillera of Cutucú (Ecuador) and characterize the corresponding active deformation of that region. For that purpose, seismological and geological data have been used, with the deployment of a temporary seismological array, with geological field observations and image processing. We found that some earthquakes are aligned on a well known NNE–SSW trend corresponding to the orientation of the nodal planes of the reverse focal mechanism of the M_w=7.0 1995 Macas earthquake as for its aftershocks. Nevertheless, many smaller events are aligned on an unexpected NNW–SSE trend inside the Cutucú Cordillera. We interpret these two orientations of the Macas swarm as linked to Subandean basement thrusts inherited from the inversion tectonics of a NNE–SSW trending Triassic–Jurassic rift, which has been uplifted and partly extruded in the Cutucú Cordillera. The present partitioning of this part of the Subandean deformation is controlled by pre-existing NNE–SSW to NNW–SSE Triassic–Jurassic normal faults that have been subsequently compressed–transpressed and reactivated into reverse faults. Major boundary faults of the rift were NNE–SSW oriented and correspond now to some main Subandean thrusts as confirms the focal mechanism of the 1995 main shock located on the eastern border (Morona frontal thrust) and the orientation of its aftershocks. In the Cutucú Cordillera, the double orientation of present swarm can be interpreted as the result of accommodation of deformation along NNW–SSE pre-existing faults inside the inverted rift system, linked to the motion of the Morona frontal NNE–SSW thrust.  相似文献   

The 1998 Hida Mountain, Central Honshu, Japan, earthquake swarm: Double-difference event relocation, frequency–magnitude distribution and Coulomb stress changes     

Bogdan Enescu  Kiyoshi Ito   《Tectonophysics》2005,409(1-4):147-157

By using the double-difference relocation technique, we have determined the fine structure of seismicity during the 1998 Hida Mountain earthquake swarm. The distribution of seismic activity defines two main directions (N–S and E–W) that probably correspond to the regional stress pattern. The detailed structure of seismicity reveals intense spatio-temporal clustering and earthquake lineations. Each cluster of events contains a mainshock and subsequent aftershock activity that decays according to the Omori law. The seismicity and the b-value temporal and spatial patterns reflect the evolution of the static stress changes during the earthquake swarm. About 80% of the swarm's best-relocated events occur in regions of increased ΔCFF. The smaller value of b found in the northern part of the swarm region and a larger b-value observed to the south, for the same period of time, could be well explained by the static stress changes caused by the larger events of the sequence. We argue that the state of stress in the crust is the main factor that controls the variation of b-value.  相似文献   

辽宁省旅游产业结构分析     

李刚  赵静玮 《世界地理研究》2006,15(2):93-99

辽宁作为全国的旅游大省之一,旅游业的发展取得了很大进步,但是在旅游产业结构方面还存在一些阻碍旅游业的健康、快速发展的问题,产业结构有待于进一步调整和优化。分别从市场结构、产品结构、行业结构、区域结构、组织结构等角度分析了辽宁省旅游产业的结构特征,并指明了旅游产业结构中存在的阻碍旅游业健康、快速发展的问题和不足,旨在促进辽宁省旅游产业结构的优化升级。  相似文献