Analysis and comparison of the tidal gravity observations obtained with LCR-ET20 spring gravimeter

Introduction The tidal variation signals of the solid Earth recorded with the modern measuring techniques can be used to provide effectively the means to cognize the Earths motion, deformation and structure character, especially to monitor the material motion in the Earths interior. In the recent 20 years, the distribution character of the global gravity field has made great progress since the continuous and deep theoretical studies in geophysics and geodesy domains. The successful manufactur…     

介休井水位异常的调查与分析

从井孔周围地下水开采量变化、大气降雨补给量变化、农田灌溉用水量变化、矿井塌方、涌水、排水和地震活动等影响因素入手 ,对 1999年至 2 0 0 0年间介休井水位的 2次突降原因进行了调查。通过初步分析 ,表明介休井水位阶降型异常具有一定的震兆性质 ,其水位的缓慢上升与突然阶降意味着介休地区断裂活动在加速。其地震预测的意义是未来一段时间山西地震带内有发生MS≥ 5 0级地震可能     

小波分析在声发射资料处理中的初步应用

针对声发射数据分析的一些难点，把最近20年发展起来的小波技术引入声发射资料处理中，分析证明结果可靠。它在本中的应用有：（1）提取有效信息。小波强大分解（细化0能力可用来从高口音中找出有效记录，分解合成时可以去掉不理想的通道，使声发射数据更加“规则化”，有望实现到时自动判读。（2）对相互叠加的事件进行有效分离。结合全波记录，可使事件尽可能少丢失，提高声发射数量统计及b值计算等的精度。（3）使成份复杂的声发射波形数据分离成具有单一特征的波，但分解后的波究竟属于P波还是S波，甚至面波，尚难确定。     

MODELING THE FATE AND TRANSPORT OF HYDROPHOBIC ORGANIC COMPOUNDS IN AN UNSTEADY RIVER-ESTUARINE SYSTEM

1 INTRODUCTION Extensive literature (Brown et al., 1985; Sawhney et al., 1981; Bierman and Swain, 1982; Connolly, 1980; Lopez-Avila and Hites, 1980; O扖onnor, 1988) described lots of sorbed pollutants or toxic substances in bed sediments of rivers, even after the effluent was halted for a long time. This is particularly true for hydrophobic organic compounds that can be sorbed on the particles and accumulated in the river bed sediments (Karickhoff et al., 1979). Pollution events of…     

Torsional vibrations of elastic foundation on saturated media

A comprehensive analytical solution is developed to examine the torsional vibration of an elastic foundation on a semi-infinite saturated elastic medium for the first time. First, the governing equations of saturated media are solved by use of Hankel transform techniques. Then, based on the assumption that the contact between the foundation and the half-space is perfectly bonded, this dynamic mixed boundary-value problem can lead to dual integral equations, which are further reduced to the standard Fredholm integral equations of the second kind and solved by numerical procedures. Numerical examples are given at the end of the paper. The numerical results indicate that the response of the elastic foundation strongly depends on the material and geometrical properties of both the saturated soil-foundation system and the load acting on the foundation. In most of the cases, the dynamic behavior of an elastic foundation on saturated media significantly differs from that of a rigid plate bearing on the elastic half-space.     

The French Guyana doleritic dykes: geochemical evidence of three populations and new data for the Jurassic Central Atlantic Magmatic Province

A petrographic and geochemical study of 15 Early Jurassic and 7 Proterozoic dolerites of French Guyana, and of one Jurassic dolerite from Ivory-Coast were carried out. The Early Jurassic SSW-NNE trending dykes have doleritic aphyric or gabbroic phyric texture. Their chemical compositions, slightly under-saturated to over-saturated, show moderate to low Mg-ratios (63–36), high TiO₂ contents (1.85–3.56 wt.%), weak rare earth element fractionation [1.8<(La/Yb)_n <4.6], negative Sr-anomalies (0.41<Sr* <0.91) and positive TiO₂-anomalies (1.2<TiO₂*<2.15). They correspond to sub-alkaline high-Ti basalts (HTiB). The La/Nb ratio (1.18±0.23) is close to that of the OIB-type Deccan basalts and incompatible element ratios: Rb/Nb_n (1.07±0.3), Zr/Y (4.6±0.8) are intermediate between those of HTiB in Deccan and those of HTiB in Paraná. These geochemical signatures and recent isotopic data of Bertrand et al. [Bertrand, H., Liegeois, J.P., Deckart, K., Féraud, G., 1999. High-Ti tholeiites in Guinea and Their Connection with the Central Atlantic CFB Province: Elemental and Nd-Sr-Pb Isotopic Evidence for Preferential Zone of Mantle Upwelling in Cause of Rifting. AGU spring meeting (Abst. p 317)] suggest that their magmatic source is different from that of the other basalts of the Central Atlantic Magmatic Province (CAMP). Such signatures are restricted to a central zone coinciding with the Panafrican Rokelides suture. We propose a model of sub-lithospheric preferential channelling of an asthenospheric ascent in this zone. Two other groups of dykes were identified in French Guyana. Compared to the Jurassic ones the Proterozoic dykes have NNW-SSE and E-W trending direction, more important LILE enrichment, low TiO₂ contents (<2 wt%) and Nb–Ta negative anomalies. Their calc-alkaline signature could be the result of a previous subduction and may be related to the 1800 Ma Venturi-Tapajós event, which contaminated the mantle source.     

Remote sensing analysis of desert vegetation and its landscape changes: The case in middle reaches of Tarim River Basin,Xinjiang, China

Based on remote sensing information sources including B/W aerial photos of 1983, pseudo-color aerial photos of 1992 and JERS-1/OPS VNIR image of 1996, vegetation types of Yingbazha, in the middle reaches of the Tarim River Basin in Xinjiang, China are mapped using ARC/INFO and related software. The changes in vegetation areas and distribution conditions are analyzed. As a result of natural and human influences, vegetation changes have temporal and spatial characteristics. According to the principles of landscape ecology and geographical information science, the landscape changes are indicated. Moreover, the remote sensing and GIS techniques are integrated to study vegetation and its landscape.     

Damage and recovery of the Gurbantunggut Desert vegetation following engineering activities

The fragile ecological environment of the Gurbantunggut Desert is damaged/disturbed by human activities relating to the development of oil-gas resources and the constructions of desert road and great engineering in the Jungger Basin. It was mainly represented: soil compaction, vegetation cleaning, burial of vegetation, oil polluting, and soil disturbance. With investigation and experiment, we found that when the way and intensity of engineering activities disturbing the eco-environment does not make its ecological stability disintegrated, the desert vegetation has a capacity of natural recovery. To speed and strengthen the process of vegetation recovery efficient assistant measurements, including stabilizing mobile sands promptly and sowing seeds of shrub and herb plants in good time will be needed.     

2001年四川省雅江-康定6.0级地震烈度考察及发震构造背景雏议

2001年2月23日四川省发生的6.0级地震，其宏观震中位于雅江县与康定县之间的高山峡谷地带．极震区烈度可达Ⅷ 度，Ⅷ 度区、Ⅶ 度区和Ⅵ 度区面积分别为180km2，1472 km2和3998 km2，等震线分布总体形态呈椭圆形，长轴近南北向．震区建筑物普遍受损，极震区山地灾害较为严重．初步分析认为，此次地震的发生与理塘断裂和玉农希断裂的长期活动有关，主干断裂活动造成的地壳应力调整和集中，最终在块体内部的次级断裂上释放而产生地震．