Study of crustal structure with S—wave data from Maqen—Jingbian profile

2-D crustal velocity structure and vp/vs are obtained by processing and interpretation of S-wave data from Maqen-Jingbian deep seismic sounding(DSS)profile.The result shows that there exist obvious differences in 2-D S-wave velocity structure and vp/vs ratio structure along the profile.The S-wave velocities are low and vp/vs ration is high for the westem section of the profile and Haiyuan region,while they are normal for the middle and eastern sections.The changes in lithologic characters of two major anomalous zones are discussed according to lateral variation of S-wave velocity structure and vp/vs ratio structure.It is concluded that the development and occurrence of the Haiyuan strong earthquake is not only related to tectonic activities,but also to lithologic characters of the region.     

SOIL CONSERVATION EFFICIENCY OF DIFFERENT MODELS CONVERTING FROM STEEP FARMING SLOPE PLOTS IN YA''''AN, SICHUAN, CHINA

Converting farming slope land into artificial forestland or grassland is a major measure of soil/water conservation. Five conversion practices, namely, 1) a control plot still tilled with a crop (maize), 2) a folder grass-growing plot seeded with Lolium perenne , 3) a young alder tree-growing plot, 4) a pear orchard plot and 5)a bamboo plot intercropped with folder grass, were monitored to compare the soil conservation efficiency of those changes in Ya'an, Sichuan for 3 years between September 1998 and August 2001. Results showed that the 5 designed converting models functioned differently in erosion control. The most effective model was bamboo groves intercropped with folder grass (Lolium perenne). The folder grass (Lolium perenne) growing model was more effective than the pure pear orchard model. The least effective model was the young alder tree-growing slope, which was even less effective than the control (a slope without converted cultivation). Meanwhile, changes in the soil's physical properties r     

Research on Earthquakes in Cities of China

In this paper, we briefly describe the general destruction caused by historic earthquakes in major cities of China, preliminarily analyze the heaviness and widespread occurrence of earthquakes in cities of China, and suggest that research on scenario earthquakes in cities should be developed as a part urban disaster reduction research.     

渭干河流域"2002·7"特大洪水分析

渭干河是塔里木河流域第六大源流, 位于天山西部南麓, 渭干河干流起点有新疆最大的流域性控制工程--克孜尔水库. 2002年7月下旬天山中西部山区出现大暴雨(雪)过程, 渭干河流域山区降水持续时间长达30 h以上, 山区降水量50 mm左右, 导致5条支流和渭干河干流出现有水文记录以来的最大洪峰, 流量超过警戒流量和危险流量的2～3.5倍, 暴雨(雪)过程结束之后, 融雪型洪峰长时间居高不下. 洪水过程中, 各支流以及暴雨与融雪等多种洪峰遭遇现象很明显. 克孜尔水库入库洪峰流量达3 660 m3*s-1, 经水库调洪错峰, 出库峰值流量为1 000 m3*s-1, 削峰率72.7%.     

吐哈盆地中央构造带正反转演化特征

吐哈盆地中央构造带由火焰山构造和七克台构造组成。中央构造带形成于三叠纪晚期至侏罗纪早期,表现为伸展构造特征,生长断层上盘地层厚度明显大于下盘,并于断层上盘所在的台北凹陷形成沉降中心。晚侏罗世,由于拉萨陆块与欧亚大陆的碰撞作用导致吐哈盆地由伸展盆地转变为挤压盆地,中央构造带也于此时发生构造反转,由早期的伸展正断层转变为挤压逆断层。发生于55Ma的喜山构造事件对天山地区产生了深刻的影响,但影响时间略有滞后,大致发生在晚渐新世至早中新世,中央构造带即在此次构造事件中强烈变形,逆冲出露于地表。     

论构造耦合作用

构造耦合作用是一种普遍存在的地质现象。现今东、西太平洋的构造差异及古太平洋和现今太平洋大陆边缘构造差异与俯冲的洋壳板块性状有关,即:①俯冲角度;②俯冲角度的改变;③俯冲速率;④俯冲速率的改变;⑤俯冲深度;⑥俯冲板块前缘与海沟间的水平距离;⑦俯冲板块在670km上、下地幔界线处的构造形态;⑧俯冲板块的位移及位移方向。这种深部构造活动对浅部构造形成的制约和影响,是活动大陆边缘构造耦合现象的具体表现。中国西北部的盆山耦合现象是大陆内部的构造耦合作用,印度板块与欧亚板块碰撞产生的远距离效应,导致中亚地区产生陆内A型俯冲,A型俯冲是造成盆地消亡、山系形成的重要因素。     

岩石断裂作用的复杂性和混沌动力学

断裂是一个复杂的动力学体系,受到岩石结构、反应、流体迁移、应力、岩石变形和力学等多种地质因素和过程的耦合控制。本文建立了断裂体系的反应-输运-力学耦合动力学模型并编制了模拟程序。以湖南水口山矿区为例,通过动力学模拟表明不同地层岩性的断裂渗透率大小和演化特征存在显著差异,断裂作用促使岩石渗透率的空间非均匀性增强,从而有利于流体的局部汇聚和矿体的形成。断裂中压力随时间呈现出非周期振荡变化,反映了断裂演化的混沌特征。     

江门市GIS建设的矢量化数据处理

结合江门市GIS工程建设中采用Epscan2.1进行地形图扫描矢量化的具体实践,对矢量化数据处理的几个突出问题作了阐述,提出了具体的解决思路与实现方法。     

PowerBuilder中MapInfo的跨平台集成地图技术的实现

随着地理信息系统的广泛应用,越来越多的大型系统中都需要集成地图的某些功能,为此探讨了在PowerBuilder中MapInfo的跨平台集成地图技术的实现。     

从激光扫描数据中进行建筑物特征提取研究

提出了一套基于建筑物几何特征的信息挖掘方案，并具体介绍了研究中采用的一些原理、方法与实用算法，从而可以直接从激光扫描数据中提取建筑物的平面外轮廓信息。利用本方案对车载激光扫描系统获取的城市建筑物试验数据进行了具体的处理，并给出了三维建模和可视化表达结果。