Fine structure of Pn velocity beneath Sichuan-Yunnan region

We use 23298 Pn arrival-time data from Chinese national and provincial earthquake bulletins to invert fine structure of Pn velocity and anisotropy at the top of the mantle beneath the Sichuan-Yunnan and its adjacent region. The results suggest that the Pn velocity in this region shows significant lateral variation; the Pn velocity varies from 7.7 to 8.3 km/s. The Pn-velocity variation correlates well with the tectonic activity and heat flow of the region. Low Pn velocity is observed in southwest Yunnan, Tengchong volcano area, and the Panxi tectonic area. These areas have very active seismicity and tectonic activity with high surface heat flow. On the other hand, high Pn velocity is observed in some stable regions, such as the central region of the Yangtze Platform; the most pronounced high velocity area is located in the Sichuan Basin, south of Chengdu. Pn anisotropy shows a complex pattern of regional deformation. The Pn fast direction shows a prominent clockwise rotation pattern from east of the Tibetan block to the Sichuan-Yunnan diamond block to southwest Yunnan, which may be related to southeastward escape of the Tibetan Plateau material due to the collision of the Indian Plate to the Eurasia Plate. Thus there appears to be strong correlation between the crustal deformation and the upper mantle structure in the region. The delay times of events and stations show that the crust thickness decreases from the Tibetan Plateau to eastern China, which is consistent with the results from deep seismic sounding.     

Re-discussion on the Jiaochang Arcuate Structure, Sichuan Province, and the Seismogenic Structure for Diexi Earthquake in 19331

The Jiaocbang arcuate structure is one of the numerous arcuate structural belts in Sichuan. The present paper gives a further argument about the characteristics of that arcuate structure and the new activity of the Songpinggou fault and affirms that the Songpinggou fault is an active fault in the Holocene epoch. The Diexi M7.5 earthquake took place in 1933 on the west wing of that arcuate structure, near the apex of the arc. Many authors have given quite different opinions about the genetic structure of that earthquake. The authors have made on-the-spot investigations time and again over recent years. Besides this, the authors have also further studied the shape of intensity contour lines, the distribution characteristics of ground surface seismic hazards, the left-lateral dislocation of buildings along the Songpinggou fault, the NWtrending ground fissures that developed on the ground surface after earthquake, and so on. On this basis, it is still considered that the seismogenic fault of the 1933 Diexi M7.5 earthquake was the Songpinggou fault on the west wing of the Jiaochang arcuate structure.     

GPS RTK测量技术的应用与体会

GPS RTK测量技术以快捷、精准的特点广泛地被测量人员所接受，但是在到量中仍存在一些问题需要研究。本文介绍了几种经常遇到的棘手问题及其解决方法。     

中国气象科学研究院深化科技体制改革

2003年，是中国气象科学研究院深化科技体制改革关键的一年，也是我院通过改革，全院职工奋发向上，精神面貌发生重大变化，各项工作取得可喜成绩的重要一年。《中国气象科学研究院深化改革实施方案》经2002年12月1117t中国气象局党组通过后，于2003年开始全面实施。领导班子明确分工，责任到人，抓好组织落实，积极稳妥地推进了我院的深化改革。     

JX—3解析测图仪上航测高倍放大成图的试验

介绍试用１：３３０００比例尺航测资料，在ＪＸ－３解析测图仪上高倍放大航测１：１０００比例尺地形图的成图方案和应采取的技术措施，运用 解析法模型绝对定向的原理，在全野布点时采用两种方案对照比较，进行理论和试验精度的分析，并给出试验结果。     

921型超低频有源伺服式速度,位移计

本介绍一种在很小体积的往复式摆上采用有源伺服技术实现超低频大幅值测量用的速度计、位移计，它可在多个频带测量速度和位移。最低频率可达０．０４Ｈｚ，最大可测位移为±１５ｍ。它可用于海浪浪高、抽油机行程、高柔结构的超低频大位移测量。该仪器于１９９２年获得国家专利，并获得中国专利博览会银奖。     

地下水对地电前兆影响的实验研究

以含水岩土为样本，研究了不同含水率，不同矿化度，不同压力，不同温度以及岩土层中重力水面的不等高度状态下岩土电阻率的定量变化，实验表明，岩土介质电阻率与所含水的特性有十分密切的关系，该实验首次把地下水前兆与地地前兆作为一个整体，来研究地者之间的内在联系，并分析其相关特征。     

既有房屋饱和土地基极限承载力增长的探讨

饱和土地基在既有房屋长期荷载作用下,地基土强度参数值随着地基土的排水固结和压密而提高,地基极限承载力也同时增大,如何估算此提高值而挖掘其潜力,传统方法只是借助于统计回归讨论了设计承载力。本文从土力学基本原理出发,借助Prandtl假定,对既有房屋饱和土地基极限承载力的增长进行了探讨。     

胶东招掖郭家岭型花岗岩锆石年代学及其Pb同位素特征

采用SHRIMP测年技术，精确地测定了郭家岭型花岗岩年龄为130-126Ma，主要金矿化在126-120Ma之间，郭家岭型花岗岩与金矿化关系最密切。岩体Pb同位素组成反映了本区所处构造背景。     

斜坡失稳时间的协同预测模型

斜坡岩体由小变形到大变形乃至滑坡的发生，实质上是由组成斜坡的各子系统协同作用的结果．将协同学引入斜坡的稳定性预测评价中，并提出了一种新的斜坡失稳时间预测模型──协同预测模型．经实例检验，该模型预测精度较高，可用于滑坡的短期或临滑预报．