地震异常平静用于短期预报的研究   总被引：9，自引：0，他引：9  

宋俊高  王炜 《地震》1994,(1):48-56

本文对我国东部十几次中强震前地震活动的中期和短期（短临）平静特征进行了深入的研究。对中期平衡，使用了归一化的Ｎ－ｔ和Ｌ－ｔ图，及地震活动统计量βｎ，由此定量确定中期平静的时间段。对短期平静，使用了归一化的Ｎ－ｔ和Ｌ－ｔ曲线，并结合主震前小震活动集中分布确定短期（短临）平静及未来主震的可能位置，根据研究区域内发生的标志地震震级估计未来主震的震级。本文还总结了中强震前几种不同的地震活动方式，但总的特征  相似文献   

丹江口水库及邻区地震震源参数研究   总被引：5，自引：0，他引：5  

严尊国  薛军蓉 《华南地震》1994,14(3):24-32

在讨论震源参数和Ｍ震级关系以及论述利用地方震尾波估算地震矩方法的基础上，尝试性地系统估算了丹江口水库及邻区内４３次ＭＬ≥２．５级地震的震源参数，并讨论了丹江口水库地震的特征。丹江口水库及邻区地震震源参数的初步分析表明：丹江口及邻区属低应力降地区。水库蓄水的附加引张应力效应可能使得丹江口水库中局部以引张应变为主的地区应变迅速增加，地震应力降高于该区一般地震原有水平、从而诱发地震。此外，丹江口水库地震的破裂长度可能和震源机制的破裂类型有关。  相似文献   

Comparative performance of indicator algorithms for modeling conditional probability distribution functions   总被引：1，自引：0，他引：1  

P. Goovaerts 《Mathematical Geology》1994,26(3):389-411

This paper compares the performance of four algorithms (full indicator cokriging. adjacent cutoffs indicator cokriging, multiple indicator kriging, median indicator kriging) for modeling conditional cumulative distribution functions (ccdf).The latter three algorithms are approximations to the theoretically better full indicator cokriging in the sense that they disregard cross-covariances between some indicator variables or they consider that all covariances are proportional to the same function. Comparative performance is assessed using a reference soil data set that includes 2649 locations at which both topsoil copper and cobalt were measured. For all practical purposes, indicator cokriging does not perform better than the other simpler algorithms which involve less variogram modeling effort and smaller computational cost. Furthermore, the number of order relation deviations is found to be higher for cokriging algorithms, especially when constraints on the kriging weights are applied.  相似文献   

岩体渗流场与应力场耦合的集中参数型数学模型研究   总被引：8，自引：2，他引：8  

仵彦卿  张倬元 《工程地质学报》1994,2(1):9-14

本文在分析岩体的地质特征、参流特征的基础上,提出了岩体渗流场与应力场耦合的集中参数型数学模型,给出了耦合集中参数型数学模型辨识的递推公式,讨论了该模型的应用前景。  相似文献   

关于深反射地震剖面采集参数的讨论   总被引：2，自引：0，他引：2  

徐明才  高景华 《物探与化探》1994,(2)

在深部地质调查中，深反射地震剖面发挥了重要作用。一般情况下，在深反射地震调查的数据采集中，采用宽频带接收、适当长的记录长度和测线跨度、大动态范围的地震仪，有利于获取深陡倾斜界面反射波；采用较大的道间距、较长的接收排列和较高的覆盖次数进行数据采集，不但可获取较准确的波速信息、高信噪比的深层反射波，而且也可提高施工效率、降低成本。  相似文献   

线形沙丘的风沙沉积特征与内部构造   总被引：4，自引：4，他引：4  

钱征宇  刘守勤 《中国沙漠》1994,14(3):25-30

本文介绍了线形沙丘不同部位风沙沉积物的粒度特征、易溶盐含量特征和颗粒形态特征，通过现场全断面开挖线形沙丘剖面，对线形沙丘的内部构造进行了观测，结合研究地区的风信资料，对线形沙丘的风沙堆积过程进行了初步分析研究。  相似文献   

关于复合片钻头钻进工艺的试验研究     

汤凤林  杨凯华  孙立朋  谭义贤 《地球科学》1993,2(1)

用试验设计方法研究了复合片钻头钻进时机械钻速、碎岩功耗、钻头磨损与规程参数的关系,求出了它们的最优值以及与其相应的钻进规程最优值。  相似文献   

Adaptive adjustment of channel geometry     

R. J. Bennett 《地球表面变化过程与地形》1976,1(2):131-150

This paper constructs a model of channel geometry composed of three subsections: a steady-state submodel, a gradedstate submodel, and a stochastic error submodel. With the aid of this representation of the morphology of channels, the at-a-point changes in geometry can be reproduced by a simple recursive equation of autoregressive, moving-average form which is derived from methods used in the statistical analysis of time series. A set of height loss data for three Japanese rivers derived from Yatsu's (1955) paper is used to determine the effect of bed material changes on adaptations within the graded-state submodel of the channel. The results of analyzing the autocorrelation function, spectrum, and adaptive parameter shifts within this model can be used to infer that significant changes in the amplitude of height change variation, and a shift to higher frequency oscillations of bed forms are associated with the shift in bed material conditions.  相似文献   

Relative performances of central and dipole frequency soundings over a layered earth     

H. P. Patra  N. L. Shastri 《Pure and Applied Geophysics》1982,120(3):527-537

Variable frequency soundings in the audio-range replaces shallow conventional direct current methods for determination of layer parameters when surface layer resistivity is high. Central frequency soundings (CFS) is one such method that involves measurement of the existing vertical magnetic field component induced at the centre of a horizontal circular or square loop. Dipole method of frequency sounding using small horizontal coplanar loops (abbreviated DFS) measuring the same field component is also considered. Theoretical studies on CFS and DFS over two- and three-layer horizontally stratified earth are carried out and the response characteristics computed and analysed.Theoretical response curves for CFS and DFS over two- and three-layer earth models are presented in convenient forms. Response curves under similar geological-physical conditions are compared. The study indicates that the relative superiority of a method is controlled largely by the nature of the conductivity contrast and the ratio of the first layer thickness to loop radius or dipole separation. While CFS shows a better resolution of conductivity contrast, DFS works better at high frequencies. For resistive substratum, however, both lack proper resolution.  相似文献   

A FUSING TECHNIQUE WITH SATELLITE PRECIPITATION ESTIMATE AND RAINGAUGE DATA^*          下载免费PDF全文

LU Naimeng  YOU Ran ZHANG  Wenjian 《Acta Meteorologica Sinica》2004,18(2):141-146

Satellite rainfall estimate can provide rainfall information over large areas,and raingauge can provide point-based ground observations with high accuracy.With the combination of satellite and raingauge data together,the estimated rainfall fields are greatly improved.This combination method,called "fusing technique",is discussed in this paper,and the validation for this technique is accomplished with HUBEX IOP data.  相似文献