1990年青海7.0级地震命名与地震前兆

较详尽地阐述了共和７．０级地震应更名为兴海地震的缘由．介绍了这次地震前出现的地下水、形变、地震活动性、气象及动物习性等地震前兆异常．最后就震时极震区出现的现象等问题阐明了作者的见解．     

宁夏南部及邻区ML≥3.0地震平静与中强以上地震的关系

通过对宁夏南部及邻区1965年以来ML≥3．0地震平静现象与中强地震的关系的分析和讨论,得到了宁夏南部4．9级以上地震发生前ML≥3．0地震的活动规律和4．9级以上地震的发生模式：平静1年→ML≥3．0地震活跃→平静4-6个月→发生地震,为今后宁夏南部的地震中短期预测提供了参考。     

2008年新疆于田MS7.3地震前区域地震活动和应力状态特征初步研究

从区域地震活动和中等地震震源机制特征的角度,初步研究了2008年新疆于田7.3级地震前区域地震活动和应力场的应力状态特征．结果表明,于田7.3级地震前区域地震活动存在中短期异常特征．一方面,该地震前1年其震区500km范围内中强震以及西昆仑地震带和阿尔金地震带3.5级以上地震出现了增强活动;另一方面,该地震前出现了4级地震孕震空区和近乎共扼分布的3.5级地震密集条带异常图象．于田7.3级地震前新疆区域应力场和震源区及其附近局部应力场的应力状态发生了一定程度的改变,拉张作用力相对挤压作用力有所加强．这可能是于田7.3级地震前新疆和于田震区及其附近具有正断层性质的中等地震增多的原因．     

地震波传播数值模拟

本文概述了地震数值模拟及其理论基础,阐述了地震数值模拟方法及特点．综述了地震数值模拟方法、三维建模和计算机硬件平台等方面的现状和进展．最后。给出了地震波数值模拟在地震勘探方法研究、地震观测系统优化设计、地震数据处理、地震资料解释、开发地震等方面的应用．     

地震活动的随机标度和非线性标度律

把地震作为一个复杂系统，研究了地震活动的随机性质．当不考虑震级范围时，全球地震活动、人震的余震和区域震群均有以幂次律为特征的长尾现象．地震的强度由震级确定，具有一特定震级的地震可形成一个地震活动系列，很多这样的地震活动系列就形成具有各种震级的地震的集合．不同地震系列间的统计特征由随机标度来表征，随机标度表明了由地震震级分类的不同地震系列间统计时刻的标度关系．为了统一地方、区域和全球地震活动性的统计特性，引入了非线性标度率．     

用于地震危险性分析的统一的伊朗地震目录

地震活动性分析把记录的地震事件作为基础数据．我们提供了一个伊朗及其邻近地区的统一地震目录用于伊朗的地震危险性分析．由于最大可信地震的复发时间不能直接从mb估算，对不同地震构造区，我们建立了经验关系，将mb转换为MS，它是我们需要的震级标度．地震目录完整性研究表明，许多中、小地震被遗漏，特别是在历史上和仪器记录早期．      

地震活动的随机标度和非线性标度律

把地震作为一个复杂系统,研究了地震活动的随机性质．当不考虑震级范围时,全球地震活动、人震的余震和区域震群均有以幂次律为特征的长尾现象．地震的强度由震级确定,具有一特定震级的地震可形成一个地震活动系列,很多这样的地震活动系列就形成具有各种震级的地震的集合．不同地震系列间的统计特征由随机标度来表征,随机标度表明了由地震震级分类的不同地震系列间统计时刻的标度关系．为了统一地方、区域和全球地震活动性的统计特性,引入了非线性标度率．     

2002年上半年全球地震活动

2002年上半年，全球发生MW≥6．5地震16次，其中13次浅源地震，2次中源地震，1次深源地震；发生MW≥7．0地震6次。上半年MW≥7．0地震的地震矩释放是1976年以来的偏低水平。中国及邻区地震活动比较活跃：3月3日，在兴都库什地区发生了1次MW7．3中源地震；6月28日，在中国吉林汪清发生了1次MW7．3深源地震。统计检验表明，地震矩释放表现出持久性质。     

东昆仑活动断裂带大地震之间的弹性应力触发研究

1937年以来沿青藏高原北部东昆仑断裂带发生了5个Ms≥7的地震：1937年Ms7．5花石峡地震，1963年Ms7．1都兰地震，1973年Ms7．3玛尼地震，1997年Mw7．5玛尼地震和2001年Mw7．8昆仑山口西地震。研究了大地震之间的应力转移和断层相互作用，计算了弹性半空间介质中地震断层措动在后续地震破裂面上产生的库仑破裂应力变化。结果表明，前面4个地震均造成后续地震的库仑破裂应力增加，有利于后续地震的发生。昆仑山口西地震之后应力变化场的计算表明东昆仑断裂中段的东大滩一西大难段的库仑破裂应力显增加，变化值达0．006～0．02MPa，预示看这一地区地震危险性的增加。     

2003年6月10日托克托MS4.2级地震的意义

2003年6月10日,呼和浩特市托克托县发生Ms4．2级地震,结束了1999年9月12日和林格尔Ms4．2级地震后呼和浩特地区ML≥3．0级地震持续45个月的异常平静。托克托Ms4．2级地震后,呼(呼和浩特)一包(包头)盆地中小地震活动显著增强,而相邻的临河盆地中小地震活动微弱。通过阴山地震带中强地震前中等地震活动特征分析,推测托克托Ms4．2级地震具有中强地震前显著地震性质。     

Fluvial geomorphology of the Middle Reach of the Huai River

The Middle Reach of the Huai River （MRHR） flows northeast into the Hongzehu Lake. Before entering the Hongzehu Lake, the Huai River has a braided channel which is shallow and wide, and the riverbed has a negative slope. Based on the characteristics of the MRHR, this river reach can be divided into the following sections： a quasi-straight （or mildly curved） section, a bend section, and a braided section. The majority of the MRHR is quasi-straight. In this paper, several parameters are used to assess the geomorphology of the MRHR. Statistical analyses are performed to establish a relationship between the span length ＂L＂ and channel width ＂B＂ for different channel patterns. The relationship between the meandering length ＂S＂ and bankfull channel width ＂B＂ is also derived. Results indicate that the bankfull channel width ＂B＂, the bankfull cross sectional area ＂A＂ and the average flow depth ＂H＂ are mainly dependent on the dominant discharge in the channel. A relationship is derived that describes the denendencv of the curvature radius ＂R＂ on the dominant discharae ＂O＂. water surface slone ＂J＂and the turning angle ＂α＂.     

A note on the general concept of wave breaking for Rossby and gravity waves

A recently proposed general definition of wave breaking is further discussed, in order to deal with some points on which misunderstanding appears to have arisen. As with surface and internal gravity waves, the classification of Rossby waves into breaking and not breaking is a generic classification based on dynamical considerations, and not a statement about any unique signature or automatically recognizable shape. Nor is it a statement about passive tracers uncorrelated with potential vorticity on isentropic surfaces. A strong motivation for the definition is that proofs of the nonacceleration theorem of wave, mean-flow interaction theory rely, explicitly or implicitly, on a hypothesis that the waves do not break in the sense envisaged.The general definition refers to the qualitative behaviour of a certain set of material contours, namely those, and only those, which would undulate reversibly, with small slopes, under the influence of the waves' restoring mechanism, in those circumstances for which linearized, nondissipative wave theory is a self-consistent approximation to nonlinear reality. The waves' restoring mechanism depends upon the basic-state vertical potential density gradient in the case of gravity waves, and upon the basic-state isentropic gradient of potential vorticity in the case of Rossby waves. In the usual linearized theory of planetary scale Rossby waves on a zonal shear flow, the relevant material contours lie along latitude circles when undisturbed.     

Solution of stochastic groundwater flow by infinite series,and convergence of the one-dimensional expansion

This paper investigates analytical solutions of stochastic Darcy flow in randomly heterogeneous porous media. We focus on infinite series solutions of the steady-state equations in the case of continuous porous media whose saturated log-conductivity (lnK) is a gaussian random field. The standard deviation of lnK is denoted . The solution method is based on a Taylor series expansion in terms of parameter , around the value =0, of the hydraulic head (H) and gradient (J). The head solution H is expressed, for any spatial dimension, as an infinite hierarchy of Green's function integrals, and the hydraulic gradient J is given by a linear first-order recursion involving a stochastic integral operator. The convergence of the -expansion solution is not guaranteed a priori. In one dimension, however, we prove convergence by solving explicitly the hierarchical sequence of equations to all orders. An infinite-order stochastic solution is obtained in the form of a -power series that converges for any finite value of . It is pointed out that other expansion methods based on K rather than lnK yield divergent series. The infinite-order solution depends on the integration method and the boundary conditions imposed on individual order equations. The most flexible and general method is that based on Laplacian Green's functions and boundary integrals. Imposing zero head conditions for all orders greater than one yields meaningful far-field gradient conditions. The whole approach can serve as a basis for treatment of higher-dimensional problems.     

基于性态的建筑工程抗震设计——《建筑工程抗震性态设计通则》述评

《建筑工程抗震性态设计通则(试用)》对抗震设计具有重要的指导意义,其中的抗震设计理念同以往的抗震设计规范在抗震设防的思路、概念和方法上有较大的区别。从工程实践的角度,比较了《通则》和现行抗震设计相关规范的区别并对具体应用提出一些看法。     

Instability on a weakening fault

Weakening of a prestressed sawcut in Westerly granite under laboratory condition is accomplished by injecting pressurized fluid into the sawcut. After injection a sequence of stick-slips is observed while the deviatoric stress decreases successively with each stick-slip. On the basis of the experimental observation we develop a model of fault instability due to inhomogeneous and progressive weakening of the fault. According to this model, the fault surface is divided into the slipped and the locked regions, depending on whether or not the local state of stress satisfies the friction criterion. The average shear stress in the slipped region decreases with time and, in order to maintain a quasi-static equilibrium, shear stress in the remaining locked region on the fault surface increases. This situation may last until a critical state of stress on the fault is met, at which a sudden instability (stick0slip) may occur. We suggest that this mechanism of stress transfer may be a viable mechanism of induced seismicity and aftershocks, in addition to the well-known mechanism of a local increase of pore pressure. By comparing the experimental data with model predictions we show that the critical condition for slip instability is when the average shear stress over the locked region becomes equal to the value given by the friction criterion. Thus the friction criterion established for slip on fractures on which the state of stress is macroscopically uniform may also be applicable to fractures on which the stress state is macroscopically heterogeneous.     

Proposte per lo sviluppo della rete meteorologica nelle Alpi Occidentali

Summary The writer wants to emphasize the necessity of reorganizing rationally the system of the meteorologic observatories in the Western Alps, especially of the ones on the highest mountains which are the most important for the study of the variations of glaciers. For that reorganization it is necessary to remember the variety of the climatic regions into which the Western Alps may be divided. The writer proposes the institution of other observatories employing the new important aerial-ropeways of Breauil and of Mount Blanc, and the new big and high-situated hotels and shelters which are opened all year round. The author insists particularly, on the necessity of doing up the observatories of Col d'Olen and Margherita on Mount Rosa which have not worked any more since ten years.     

“十五”测震台网数据库的应用程序开发

通过介绍地震数据查询和分析处理软件的编程经验,简要阐述了基于“十五”测震台网数据库客户端应用程序的开发思路。“十五”测震台网Jopens系统数据库,为开发Windows环境下的地震数据分析处理软件提供了良好的在线数据资源,借助MySql ODBC驱动程序开发Mysql客户端软件不失为一种较好的方法。     

Very low frequency (VLF) chorus emissions: A topical survey

In this paper we have tried to present, coherently, a review of the observations of natural VLF radio emissions, termed chorus, that have been made on the ground and aboard satellites, and also their dependence on various geomagnetic phenomena. We have highlighted current theoretical interpretations of the generation and propagation of chorus signals.     

Perturbation of eigenfrequencies of a cylinder due to a ridge on the surface

Summary An infinite cylinder is assumed to have a small ridge on the surface. The effect of the ridge on the eigenfrequencies of flute mode of oscillation is obtained in the linear approximation. The usefulness of these results in seismological problems is indicated.     

Verification and refinement of spectral magnitude calibrating functions for P-waves

Calibrating functions for determination of P-wave spectral magnitudes calculated by Duda and Yanovskaya (1994) on the basis of the IASP91 velocity model and the PREM Q-model are verified empirically. For this purpose IRIS broadband records for 120 earthquakes are used, each earthquake having been recorded at about 100 stations. The discrepancies indicate that anelastic absorption assumed in PREM is too high. New calibrating functions are calculated on the basis of the AK135 velocity and anelasticity models (Kennet et al., 1995; Montagner and Kennet, 1996), in which Q in the mantle is higher than in PREM. The verification of the new calibrating functions based on the same observations yields magnitude figures less depending on the epicentral distance. In addition the parameter ₂in the Liu-Anderson Q(T) model is estimated, proceeding from the assumption that on the average the radiated spectra comply with the ²-model. The value of ₂ was assumed to be 0.1 s in the analysis and its use resulted in the verification of the ²-model for the source spectrum.