New seismological constraints on differential rotation of the inner core from Novaya Zemlya events recorded at DRV, Antarctica

Novaya Zemlya nuclear test records at the seismic station DRV, Antarctica, are analysed in order to obtain further constraints on a possible differential rotation of the inner core with respect to the mantle. These data allow the sampling of the inner core along a nearly polar path in very stable conditions over more than two decades, from 1966 to 1990. The PKP (BC)– PKP (DF) traveltime residuals, which reflect the inner-core anisotropy and/or heterogeneities sampled along the path, exhibit a great stability through time. A computation of the residuals that are expected for various differential rotation rates and the same rotation axis as the mantle has been performed using the worldwide residual catalogue of Engdahl et al . (1997) for summary rays that include the time as an additional parameter in data stacking. Comparison of data and predictions shows that an eastward differential rotation with a rate as large as 3°  yr⁻¹, as suggested by some authors, is not possible, but an eastward rotation at 1°  yr⁻¹ or lower cannot be rejected.     

荆山群的地层结构及野头组含金性研究

在荆山群建组剖面实地研究的基础上,补测了野头组的禄格庄剖面,考察了荆山区至平度区荆山群的相变规律,采用数学地质方法研究荆山群地层结构及生成环境,得知：荆山群无论在原岩建造、岩性组合、生成的古地理环境均不同于胶东岩群。荆山群形成于不稳定的冒地槽环境,相变剧烈,由荆山区至平度区厚度锐减,火山活动减弱。荆山群在总体上表现为三大周期,对应三个组,各组内部具有不同的沉积韵律和拟周期,野头组火山沉积和禄格庄组的砂泥质沉积是荆山群金的高丰度部位。野头组的火山建造形成于海底裂陷环境,金主要赋存在正常沉积与火山沉积的交变带中。产于进入火山活动和由火山活动转出的历史阶段,属火山喷气—溢流阶段的产物。     

从地震地质学角度对震后的地震活动趋势进行预测

本文从地震地质学的角度，通过综合分析、数理统计和实际计算获得了判定地震序列类型的定量和定性指标，提出了中小地震（群）后地震活动趋势和大震后强余震预报的地震地质学方法，通过一些地震实例的实践与检验，证明本文提出的方法是行之有效的，可用于震后地震活动趋势的预测和预报。     

长江下游感潮河段大洪水和特大洪水的形成及趋势

分析了长江下游感潮河段大洪水和特大洪水高水位形成的水文因素,揭示了年最高水位今后一段时期内可能的变化趋势。主要结论是:该河段大洪水和特大洪水高水位的形成原因十分复杂,本世纪以来每次大洪水和特大洪水高水位的形成几乎都有其主要原因;该河段大洪水特大洪水高水位出现的频次有增加趋势;自1975年以来,年最高水位的均值呈明显的升高趋势,其主要原因是人类活动对防洪产生的负面影响,海平面上升也有一定的影响。     

甘改—玉树断裂带的近代地震与未来地震趋势估计

通过对甘改－玉树断裂带上近代地震的震级，震中位置和地震地表破裂的空间展布特征的研究，采用Ｎｉｓｈｅｎｋｏ和Ｂｕｌａｎｄ发展的“特征地震复发时间通用分布”概率模型，即“ＮＢ”模型，对甘孜玉树断裂带各段落未来５０ａ内强震趋势进行了估计。     

径流的趋势分析和概率预测

对永定河流域的官厅水库和汾河流域的汾河水库1950年以来水库入流的趋势变化进行了研究,并对引起这一变化的气象因子和人类活动影响因素作了分析。研究结果表明,降水的多年波动在一段时期可能出现的趋势变化以及流域内农业、林业和城市用水的逐年增长是影响径流趋势变化的主要因素。根据历史资料和今后人类活动的可能情况,对未来水平年的径流变化进行了概率预测。     

Estimating Variogram Uncertainty

The variogram is central to any geostatistical survey, but the precision of a variogram estimated from sample data by the method of moments is unknown. It is important to be able to quantify variogram uncertainty to ensure that the variogram estimate is sufficiently accurate for kriging. In previous studies theoretical expressions have been derived to approximate uncertainty in both estimates of the experimental variogram and fitted variogram models. These expressions rely upon various statistical assumptions about the data and are largely untested. They express variogram uncertainty as functions of the sampling positions and the underlying variogram. Thus the expressions can be used to design efficient sampling schemes for estimating a particular variogram. Extensive simulation tests show that for a Gaussian variable with a known variogram, the expression for the uncertainty of the experimental variogram estimate is accurate. In practice however, the variogram of the variable is unknown and the fitted variogram model must be used instead. For sampling schemes of 100 points or more this has only a small effect on the accuracy of the uncertainty estimate. The theoretical expressions for the uncertainty of fitted variogram models generally overestimate the precision of fitted parameters. The uncertainty of the fitted parameters can be determined more accurately by simulating multiple experimental variograms and fitting variogram models to these. The tests emphasize the importance of distinguishing between the variogram of the field being surveyed and the variogram of the random process which generated the field. These variograms are not necessarily identical. Most studies of variogram uncertainty describe the uncertainty associated with the variogram of the random process. Generally however, it is the variogram of the field being surveyed which is of interest. For intensive sampling schemes, estimates of the field variogram are significantly more precise than estimates of the random process variogram. It is important, when designing efficient sampling schemes or fitting variogram models, that the appropriate expression for variogram uncertainty is applied.     

趋势面分析在山西朔州王坪井田构造研究中的应用

针对王坪井田3号煤层底板起伏变化大．严重影响开拓及采煤巷道布置的现状．利用趋势面分析的方法．分析了井田内的构造展布规律．研究表明．井田在主向斜的基础上．存在次级背斜和NE和NW两组断裂．与本区受到多期次的构造应力场作用相吻合．得出的3号煤层底板高程二次趋势面方程．可为3号煤层开拓及采煤巷道的设计提供地质依据．     

Comparing liquefaction evaluation methods using penetration-VS relationships

Three methods that follow the general format of the Seed-Idriss simplified procedure for evaluating liquefaction resistance of soils are compared in this paper. They are compared by constructing relationships between penetration resistance and small-strain shear–wave velocity (V_S) implied from cyclic resistance ratio (CRR) curves for the three methods, and by plotting penetration-V_S data pairs. The penetration-V_S data pairs are from 43 Holocene-age sand layers in California, South Carolina, Canada, and Japan. It is shown that the V_S-based CRR curve is more conservative than CRR curves based on the Standard Penetration Test (SPT) and Cone Penetration Test (CPT), for the compiled Holocene data. This result agrees with the findings of a recent probability study where the SPT-, CPT-, and V_S-based CRR curves were characterized as curves with average probability of liquefaction of 31, 50, and 26%, respectively. New SPT- and CPT-based CRR equations are proposed that provide more consistent assessments of liquefaction potential for the Holocene sand layers considered.