华北地区地震造成人员死亡的概率预测研究初探

在1800年至1989年间,华北地区(34.0°—42.0°N;117.5°—125.0°E)由于地震造成人员死亡程度(E)(E—logD,D为死亡人数)及其频度(N)满足指数关系N=37.71e~(-0.72E)。应用Gumbel极值理论估计该区在1988—1998年和1999—2009年间,地震造成人员死亡人数等于和大于1000人的概率分别是0.37和0.50。     

地震综合预报的权重集成法

本文提出一种地震综合预报方法,即权重集成法。该方法首先根据各单项前兆或方法历史预报的错报率,计算其权重值,据此建立权重集成预报方程。其后据此方程采用历史回代法求其权重集成值P,最后根据历史上对应有震的权重集成的最小值和对应无震的最大值,求出权重集成值的临界阀值P_0。当P≥P_0时则作有震预报,否则作无震预报。该方法简便、综合性强。     

西秦岭北缘断裂带特征地震平均复发间隔的确定和地震危险性评价

时间相依的地震危险性概率评估方法是最近10a来逐渐发展起来的，是一种将已获得的定量地质资料运用于活动断裂中—长期地震潜势概率评估的方法，从而使得在缺乏历史记载或仪器记录资料，但已获得断层平均滑动速率、同震位错、古地震年代序列等资料的活动断裂段上评估未来的发震概率成为可能。在定量计算活动断裂未来地震危险性的过程中，作为输入参数之一的特征地震平均复发间隔是一个至关重要的参数，它的确定将直接影响到概率计算的结果。对研究断裂上已获得的历史地震资料(H)、地质资料(G)和古地震资料(P)，笔采用了时间可预报(T)和准周期(Q)两种模式分别计算其平均复发间隔，比单一的只假定一种复发模式计算更具有完善性和可靠性。在叙述该方法的同时，以西秦岭北缘断裂为例，详细阐述了该断裂上特征地震平均复发间隔的确定，并在此基础上对西秦岭北缘断裂未来地震潜势作了定量评估。     

Associations between the Autumn Arctic Sea Ice and North American Winter Precipitation

Associations between the autumn Arctic sea ice concentrations (SICs) and North American winter precipitation were examined using singular value decomposition. The results show that a reduced SIC in the majority of the Arctic is accompanied by dry conditions over the Great Plains, the southern United States, Mexico, eastern Alaska, and southeastern Greenland, and by wet conditions over the majority of Canada, the northeastern United States, and the majority of Greenland. Atmospheric circulation anomalies associated with the SIC variability show a wave train structure that is persistent from autumn to winter and is responsible for the covariability between the autumn Arctic SICs and North American winter precipitation. This relationship suggests a potential long-term outlook for the North American winter precipitation.     

冰冻圈服务评估方法探讨

冰冻圈服务指人类能够从冰冻圈中直接或间接获得的各种惠益,由冰冻圈的过程和功能产生,可为人类生存和发展提供重要的物质和文化基础。随着冰冻圈科学的发展,人们对冰冻圈过程和功能的认识不断深化,同时冰冻圈科学研究如何为区域可持续发展服务也成为重要的关注点,受到冰冻圈科学界的重视。然而,作为冰冻圈服务研究的重要内容之一,人们对冰冻圈服务评估方法仍缺乏系统性探讨。鉴于此,本研究从物质量法、价值量法和能值分析法三个维度对各类冰冻圈服务的评估方法进行了探讨。通过对这三种方法的原理、基本使用准则、适用范围和优缺点进行分析,以期探寻评估各类冰冻圈服务的最适方法,从而为后期开展具体评估提供方法借鉴。     

奇异值分解法与阻尼最小二乘法的对比

本文根据电阻率测深曲线的一维反演中对初始模型的要求和收敛速度，论述了奇异值分解法（维根斯法）与阻尼最小二乘法（马奎特法）的优缺点     

基于误差方程常数项的变权迭代法在核电测量中的运用

测量平差处理过程中对大量的观测数据进行误差性质的有效实时甄别,尽量减少误差较大的观测值对最终成果质量的显著影响,在测量数据处理中具有重要的意义。结合核电平面控制测量特点,给出了判别方向、距离观测异常值阀值的简易计算方法,可以对异常观测值进行有效探测;指出在求解待定点未知参数前对异常值进行动态定权,可以保证最终观测成果质量不受异常值的显著影响,相对稳健估计利用验后观测值残差动态定权,可以提高数据处理效率及质量。     

Empirical statistical characterization and regionalization of amplitude–duration–frequency curves for extreme peak flows in the Lake Victoria Basin,East Africa

Abstract

This paper focuses on a regionalization attempt to partly solve data limitation problems in statistical analysis of high flows to derive discharge–duration–frequency (QDF) relationships. The analysis is based on 24 selected catchments in the Lake Victoria Basin (LVB) in East Africa. Characteristics of the theoretical QDF relationships were parameterized to capture their slopes of extreme value distributions (evd), tail behaviour and scaling measures. To enable QDF estimates to be obtained for ungauged catchments, interdependence relationships between the QDF parameters were identified, and regional regression models were developed to explain the regional difference in these parameters from physiographic characteristics. In validation of the regression models, from the lowest (5 years) to the highest (25 years) return periods considered, the percentage bias in the QDF estimates ranged from –2% for the 5-year return period to 27% for 25-year return period.

Editor D. Koutsoyiannis     

A transient phreatic surface mound,evidenced by a strip of vegetation on an earth dam

Abstract

On the slopes of the embankment of the Al-Khod groundwater recharge–flood protection dam (Oman), a band of scrub vegetation community emerged after torrential rains and temporary filling of the dam reservoir. Species composition differs markedly on both sides of the embankment, with many exotics found on the reservoir side and more typical gravel-desert species on the outside. Hydro-ecologically, the vegetation is interpreted as the footprint of a temporary storage of water, which is a small-sized groundwater mound within the permeable shoulder of the levee. The levee, as an anthropogenic landform, induces a U-turn (gravitational slumping–lateral seepage–transpirational moisture ascent) topology of seepage. The Lembke method of successive variations of steady states is used in modelling the water table dynamics. In the early stage of the mound decay, outflow through a seepage face of the shoulder is modelled by the Barenblatt slumping parabola of the phreatic-zone part of the flow domain, which is perfectly matched with the Youngs exact solution for a purely horizontal flow through a porous wedge. At the stitching cross-section, the flow rates and saturated depths in the two zones coincide. The late stage of mound evolution is characterized by transpiration by the plant roots projected onto a shrinking free surface, with the Barenblatt and Youngs solutions conjugated but without the outcrop of the saturated mound on the levee slope. Ordinary differential equations for the sliding or descending locus of the intersection of the parabola and the triangle hypotenuse are integrated in a closed form or by the Runge-Kutta method. The dwindling saturated volume and the rate of drainage are obtained. They can be used in assessments of the hydro-ecological sustainability of slope-rooted shrubs (vegetation survival between rare rainfall episodes).

Editor D. Koutsoyiannis; Associate editor A. Porporato