东昆仑活动断裂带东段古地震活动特征   总被引：12，自引：0，他引：12       下载免费PDF全文

李春峰  贺群禄  赵国光 《地震学报》2005,27(1):60-67

东昆仑活动断裂托索湖——玛曲以东肯定那一带， 可据阿尼玛卿玛积峰为界再分为花石峡段和玛沁段两个在几何上不连续的段落. 两段在表征断层全新世活动特征的古地震事件方面有明显差异， 花石峡段的地震活动性明显高于玛沁段的地震活动性. 古地震研究表明， 花石峡段上3次强震活动相邻两次地震发生的时间间隔分别约为500 a和640 a， 玛沁段上最近两次古地震事件间大致有1 000 a左右的时间间隔. 根据断层平均滑动速率计算的花石峡段7.5级地震的平均复发间隔为411~608 a， 相对应的同震平均水平位错约为（5.75plusmn;0.57）m. 虽然玛沁段的地震活动性较弱， 但由于该段上最近一次地震事件离现在较为久远， 已经积累的应变能应该使我们对其未来地震危险性的分析有足够重视.   相似文献   

川藏公路然乌-鲁朗段地质灾害影响因素定量分析     

丁继新  尚彦军  杨志法  尹俊涛 《水文地质工程地质》2005,32(4):1-5

川藏公路然乌—鲁朗段工程地质条件极其复杂,导致大型地质灾害频繁发生。为了定量地分析各种影响因素对大型地质灾害的贡献,本文根据信息熵的理论和方法,提出了“地质灾害熵”的概念。通过详细分析川藏公路然乌—鲁朗段大型地质灾害资料,选择平均坡度、断层和节理、岩体结构、松散堆积物、水文地质条件、冰川作用和降雨等7个影响因素,分析它们对研究区某些大型地质灾害的影响程度,计算出了各影响因素的“地质灾害熵”。根据“地质灾害熵”计算得到了各影响因素的权重,在一定程度上解决了地质灾害影响因素的定量分析问题。  相似文献   

表层岩溶带调蓄系数定量计算--以湘西洛塔赵家湾为例   总被引：2，自引：1，他引：2  

邹胜章  张文慧  梁小平  罗伟权  梁彬 《水文地质工程地质》2005,32(4):37-42

本文以湖南洛塔赵家湾表层岩溶系统为例,综合利用水位、降雨量、蒸发量及泉流量等长观资料,分别对不同降雨特征下的表层岩溶带调蓄系数进行了定量计算,并对影响表层岩溶带调蓄能力的因素进行了分析。计算得到丰水期赵家湾表层岩溶带调蓄系数为0 14～0 2 8,明显小于枯水期调蓄系数0 44 ;但丰水期久旱后表层岩溶带的调蓄能力接近于枯水期;在丰水期,场雨和连续降雨时的调蓄能力比间歇降雨时的小近1倍。实例计算表明:赵家湾表层岩溶带具有一定的调蓄能力,其地下迳流滞后于降雨至少3d ,调蓄系数确实可以用来定量评价表层岩溶带的调蓄能力。  相似文献   

用生物标志物定量计算混合原油油源的数学模型   总被引：9，自引：0，他引：9  

陈建平  邓春萍  宋孚庆  张大江 《地球化学》2007,36(2):205-214

多烃源层叠合盆地混源油油源的定量计算是十分困难的问题.典型原油的人工混合配比实验显示,当两个生物标志物浓度不同的原油相混合时,各类生物标志物的比值参数随端元原油混入量呈非线性变化,以生物标志物比值参数和简单的二元线性关系方程定量计算混源油的混合比例将导致错误的结论.三个或者三个以上原油相混合时,各类生物标志物比值参数的变化更加复杂,各端元原油的贡献更加难以判识.但是,人工混合模拟实验表明混合油中生物标志物绝对含量与端元油的混入量呈线性关系,数学推导证明了这种线性关系,由此推导出相应的数学计算模型,其中:二元混合时比值参数与混入量呈双曲线关系,三元混合呈双曲面关系,四元及其以上的多元混合呈多维曲面,可以矩阵的方式定量计算各端元油的比例.依据这些数学模型,应用生物标志物的绝对含量和(或)生物标志物比值参数均可以定量计算出混源原油中各类原油的贡献比例.数学模型比通常的人工模拟实验方法更加经济、方便、精确和可靠.  相似文献   

Application of bivariate extreme value distribution to flood frequency analysis: a case study of Northwestern Mexico   总被引：1，自引：0，他引：1  

Carlos Escalante-Sandoval 《Natural Hazards》2007,42(1):37-46

In Mexico, poverty has forced people to live almost on the water of rivers. This situation along with the occurrence of floods is a serious problem for the local governments. In order to protect their lives and goods, it is very important to account with a mathematical tool that may reduce the uncertainties in computing the design events for different return periods. In this paper, the Logistic model for bivariate extreme value distribution with Weibull-2 and Mixed Weibull marginals is proposed for the case of flood frequency analysis. A procedure to estimate their parameters based on the maximum likelihood method is developed. A region in Northwestern Mexico with 16 gauging stations has been selected to apply the model and regional at-site quantiles were estimated. A significant improvement occurs, measured through the use of a goodness-of-fit test, when parameters are estimated using the bivariate distribution instead of its univariate counterpart. Results suggest that it is very important to consider the Mixed Weibull distribution and its bivariate option when analyzing floods generated by a␣mixture of two populations.  相似文献   

Inverse groundwater modelling in the Willunga Basin,South Australia     

Ian Knowles  Michael Teubner  Aimin Yan  Paul Rasser  Jong Wook Lee 《Hydrogeology Journal》2007,15(6):1107-1118

A new inverse technique for modelling groundwater flow, based on a functional minimization technique, has been used to calibrate a groundwater flow model of a subregion of the Port Willunga aquifer within the Willunga Basin in South Australia. The Willunga Basin is the location of extensive viticulture, irrigated primarily by groundwater, the levels and quality of which have declined significantly over the last 40 years. The new method is able to generate estimates of transmissivity, storativity and groundwater recharge over the whole subregion as a time-varying continuous surface; previous methods estimate local discrete parameter values at specific times. The new method has also been shown to produce accurate head values for the subregion and very good estimates of groundwater recharge. Its ultimate goal will be to provide a new and invaluable tool for significantly improved groundwater resource management. Supported in part by US National Science Foundation grants, DMS-0107492 and DMS-0079478.  相似文献   

Hybrid Estimation of Semivariogram Parameters   总被引：1，自引：0，他引：1  

Hao Zhang  Dale L. Zimmerman 《Mathematical Geology》2007,39(2):247-260

Two widely used methods of semivariogram estimation are weighted least squares estimation and maximum likelihood estimation. The former have certain computational advantages, whereas the latter are more statistically efficient. We introduce and study a “hybrid” semivariogram estimation procedure that combines weighted least squares estimation of the range parameter with maximum likelihood estimation of the sill (and nugget) assuming known range, in such a way that the sill-to-range ratio in an exponential semivariogram is estimated consistently under an infill asymptotic regime. We show empirically that such a procedure is nearly as efficient computationally, and more efficient statistically for some parameters, than weighted least squares estimation of all of the semivariogram’s parameters. Furthermore, we demonstrate that standard plug-in (or empirical) spatial predictors and prediction error variances, obtained by replacing the unknown semivariogram parameters with estimates in expressions for the ordinary kriging predictor and kriging variance, respectively, perform better when hybrid estimates are plugged in than when weighted least squares estimates are plugged in. In view of these results and the simplicity of computing the hybrid estimates from weighted least squares estimates, we suggest that software that currently estimates the semivariogram by weighted least squares methods be amended to include hybrid estimation as an option.  相似文献   

Fuzzy Modeling for Reserve Estimation Based on Spatial Variability   总被引：1，自引：0，他引：1  

Bulent Tutmez  A. Erhan Tercan  Uzay Kaymak 《Mathematical Geology》2007,39(1):87-111

This article addresses a new reserve estimation method which uses fuzzy modeling algorithms and estimates the reserve parameters based on spatial variability. The proposed fuzzy modeling approach has three stages: (1) Structure identification and preliminary clustering, (2) Variogram analysis, and (3) Clustering based rule system. A new clustering index approach and a new spatial measure function (point semimadogram) are proposed in the paper. The developed methodology uses spatial variability in each step and takes the fuzzy rules from input-output data. The model has been tested using both simulated and real data sets. The performance evaluation indicates that the new methodology can be applied in reserve estimation and similar modeling problems  相似文献   

Aspiration and reality: flood policy, economic damages and the appraisal process   总被引：1，自引：0，他引：1  

Clare Johnson  Edmund Penning-Rowsell  Sue Tapsell 《Area》2007,39(2):214-223

Research shows that flood damage potential has increased significantly in the last 15 years. At the same time, flood policy has shifted away from simplistic flood defence towards 'living with floods' and 'making space for water'. This paper explores the mis-match between the aspiration in policy ideals, the reality of rising potential economic damages and the inability of the flood risk appraisal process to match the aspiration with the reality. Unless investment appraisal procedures are changed, the increase in damages will undermine policy changes that seek a different pattern of flood risk management, away from economically dominated decision-criteria towards more sustainable objectives.  相似文献   

Inferred ground motions on Guadeloupe during the 2004 Les Saintes earthquake     

John Douglas 《Bulletin of Earthquake Engineering》2007,5(3):363-376

Accurate estimates of the ground motions that occurred during damaging earthquakes are a vital part of many aspects of earthquake engineering, such as the study of the size and cause of the uncertainties within earthquake risk assessments. This article compares a number of methods to estimate the ground shaking that occurred on Guadeloupe (French Antilles) during the 21st November 2004 (M _w 6.3) Les Saintes earthquake, with the aim of providing more accurate shaking estimates for the investigation of the sources of uncertainties within loss evaluations, based on damage data from this event. The various techniques make differing use of the available ground-motion recordings of this earthquake and by consequence the estimates obtained by the different approaches are associated with differing uncertainties. Ground motions on the French Antilles are affected by strong local site effects, which have been extensively investigated in previous studies. In this article, use is made of these studies in order to improve the shaking estimates. It is shown that the simple methods neglecting the spatial correlation of earthquake shaking lead to uncertainties similar to those predicted by empirical ground-motion models and that these are uniform across the whole of Guadeloupe. In contrast, methods (such as the ShakeMap approach) that take account of the spatial correlation in motions demonstrate that shaking within roughly 10 km of a recording station (covering a significant portion of the investigated area) can be defined with reasonable accuracy but that motions at more distant points are not well constrained.  相似文献