中国大陆西部及邻近地区地震活动的小波分析

利用能反映非平稳信号时频域特征的小波分析方法，分析了百年来中国大陆西部及邻近大三角地区的地震资料，得到了地震活动在不同时间尺度上的特征。百年来该地区地震活动主要周期分别为42年、22年、7年和14年，而且其强度随时间在变化，由此我们认为对于地震活跃或平静期的讨论只有建立在具体的时间尺度上才有意义。同时利用各种尺度的小波系数和地震活动主周期对未来地震趋势进行的分析表明，未来几年该区地震活动仍相对较为活跃。     

油气区地表黄土磁化率异常直接指示油气藏研究

油气区地表黄土具有磁化率异常,早已是一 个不争的事实,而为什么会产生这种异常,以及这 种异常对探测油气藏是否具有某种指导性意义,一 直是国内外油气地球物理工作者关注和研究的课题 之一。本文作者对油气区地表黄土磁化率异常成因 进行了分析,并采用适当的数学手段,对中国西部 某油气区黄土样品磁化率观测值进行了处理;合理 地划分出黄土磁化率背景值,根据磁化率异常确定 油气远景区和量化评价因子。经过实际油井验证, 证明了应用磁化率指示油气藏信息的有效性。     

北极新奥尔松地区现代污染源及其指示植物研究

分析了采自北极新奥尔松(Ny-lesund)(78°55′N,11°56′E)煤矿开采区水平剖面12个点位上的三种苔原植物Dicranumangustum(苔藓类植物)、Puccinelliaphryganodes(穗状植物)和Salixpolaris(管状植物)及土壤中10种重金属(Hg、Pb、Cd、Cu、Zn、Ni、Fe、Mn、As、Se)及S、TOC的含量。结果显示采矿过程中煤层的暴露是本地区的Hg、Cd、S污染的主要来源。三种分布最广泛、数量最多的苔原植物中苔藓植物Dicranumangustum对重金属元素具有最大的富集能力,位于矿区的Dicranumangustu体内污染元素含量显著高于非矿区部分,这也说明该水平剖面上的元素污染是由当地煤矿开采导致的。同时发现,Dicranumangustum体内元素积累和土壤中元素浓度之间沿水平剖面的变化趋势较一致,能较好地反映本地区的污染状况,可以作为污染监测和指示植物。从全球区域对比来看,北极新奥尔松苔藓体内污染水平显著低于邻近的北欧等工业区,但却是北极地区Hg、Cd和S污染最严重地区,同时也比南极地区高。     

Deflation rates of different clastic sediments in the arid regions of China

By wind tunnel experiment, we studied the deflation rates of 8 different clastic sediments in the arid regions of China, discussed the sources of aeolian sand and their influence on the development of sand dunes and formation of sand deserts from the view of dynamics of wind erosion. The average deflation rates of 8 typical clastic sediments in the arid regions of China can be arranged in the order of lacustrine sand > alluvial sand > weathered sandstone and shale > pluvial sediments > fluvioglacial sand > weathered granite > slope deposit > glacial sediments. The deflation rates exhibited strong positive correlations with the erodible particle (0.063–2mm) content and sorting features. In contrast, the deflation rates had obvious negative correlations with the contents of silt clay (<0.063 mm) and gravel (>2 mm). According to the deflation rates, the 8 typical clastic sediments can be divided into four categories: (1) lacustrine and alluvial sand, which are readily prone to wind erosion, assumed to be the main source of aeolian sand; (2) weathered sandstone and shale, pluvial sediments and fluvioglacial sand with considerable deflation rates, might be the secondary source of aeolian sand; (3) weathered granite and slope deposit having the lower deflation rates, could supply a little aeolian sand; and (4) glacial sediments with a strong anti-erodibility, could hardly offer any aeolian sand. In addition to the strong wind conditions, the exposure of extensive lacustrine sand induced by the desiccation of inland lake basin, as well as the pre-sorting of clastic sediments by flowing water should be the key factors influencing the development of sand deserts in China. The possible reason the sand deserts in China being mostly distributed around the inland lake basins and along riverbanks could be better understood through sand source analysis.     

The 1920S Drought Recorded by Tree Rings and Historical Documents in the Semi-Arid and Arid Areas of Northern China

Using a network of tree-ring data, we show that there had been significant growth decline in the 1920s and early 1930s throughout a wide area of northern China. This growth depression is indicative of a severe and sustained drought in the 1920s and early 1930s, which was then confirmed with a variety of historical and instrumental records including hydrological, meteorological, and documentary evidence. The 1920s drought had a devastating effect not only on agricultural productivity, hydrological resources and society in the affected areas, but also on natural vegetation, as inferred from the tree-ring network and historical records. This research offers a picture of the drought calamity during the 1920s and early 1930s in northern China, and demonstrates the potential to identify spatial anomalies of large-scale drought using tree-ring networks in the semi-arid and arid areas of northern China.     

A Scheme for Scalar Exchange in the Urban Boundary Layer

We present a scheme for parameterising scalar transfer in the urban boundary layer, which is divided into an inertial layer and a roughness layer. The latter is further divided into a shear layer and a canyon layer. In the inertial layer, scalar transfer is determined by turbulence related to canyon macroscopic features, while in the roughness layer, it is determined by shear-generated turbulence, canyon vortex and vortex-generated turbulence. We first describe a conceptual model for the canyon flow and the aerodynamic resistance network, and then estimate the resistances from the point of view of drag partition and vortex advection. The results are compared with the measurements from wind-tunnel experiments. It is found that for small canyon aspect ratio, σ_c, the transfer velocity increases with σ_c, reaching a maximum at around σ_c=0.5 and then decreases with σ_c. We also show that the scheme is not sensitive to adjustable parameters     

台湾海峡南部一次5.0级地震的sPn震相分析

运用Pn震相对齐测定sPn震相的方法分析了发生在台湾海峡南部的一次5．0级地震的 sPn震相,初步了解sPn震相的一些特征,并在不同地壳模型下用sPn-Pn的走时差计算了该地震的震源深度。结果表明:在该地震中,sPn震相特征明显;用Pn震相对齐测定sPn震相的方法可以快速、可靠地测定出sPn震相;用sPn-Pn的走时差计算震源深度时,不同模型计算出的结果相差不大。     

首波震相跟踪系统

本文简述了首波震相跟踪系统的主要功能和技术。     

淮北煤田矿井充水因素与防治水措施研究

淮北矿区矿井突水的主要充水水源是老窑积水、新生界松散层底部含水层（组）水、煤层顶、底板砂岩裂隙水、太原组与奥陶系灰岩水。矿井众多重大突水事故表明，加强太原组、奥陶系石灰岩含水层和断层破碎带的探测与疏放工作，是降低煤矿突水风险的必要条件。     

景德镇市“97-11-25”大暴雨初步分析

对产生“97-11-25”景德镇市大暴雨天气的环流背景、低空急流活动、假相当位温θse及本站要素变化做了初步分析。西南暧湿气流的向北输送,大气层结的不稳定是产生这次大暴雨和雷暴天气的关键。