Study on the characteristics of earthquake''''s impact on cities

Introduction With rapid development of national economy, urbanization has been speeded up in China, and several city groups or city belts with extra-large cities as their centers have been formed. For example, Pearl River Delta urbanized area surrounds Guangzhou City, Shenzhen City, Zhuhai City; Yangtze River Delta urbanized area surrounds Shanghai City, Suzhou City, Wuxi City, Nanjing City, Hangzhou City; Beijing-Tianjin-Tangshan urbanized area surrounds Beijing City, Tianjin City…     

Study on the correlativity of earthquakes impact on cities

Introduction With rapid development and advancement of economy and society, lots of city groups or city belts with ex-tra-large cities as their centers have been formed in China. The regions these city groups lie in usually have well-developed economy, dense population, and are regional politics and culture centers. Some groups lie in the regions with high level of earthquake activity, such as the Surrounding Capital City Group with the centers of Bei-jing and Tianjin. Once a large earthqua…     

Research on the Characteristics of Large Earthquake Activity on the Active Tectonic Boundaries on the Chinese Mainland

INTRODUCTIONThe active blocks refer tothe geologic units that formedinlate Cenozoic (100 ~120 ka BP) andhave been highly active as fault zones since late Quaternary with relatively uniform motion styles(Zhang Guomin,et al .,2000 ;Zhang Peizhen,et al .,2003) .The active blocks are relativelyintactand have uniformmotion modalities ,their boundary zones (also called the active boundaries) are thelocalized or centralized zones of interactions and differential movement among the active block…     

Studies on seismic waves

The development of seismic wave study in China in the past four years is reviewed. The discussion is divided into several aspects, including seismic wave propagation in laterally homogeneous media, laterally heterogeneous me-dia, anisotropie and porous media, surface wave and seismic wave inversion, and seismic wave study in prospect-ing and logging problems. Important projects in the current studies on seismic wave is suggested as the develop-ment of high efficient numerical methods, and applying them to the studies of excitation and propagation of seis-mic waves in complex media and strong ground motion, which will form a foundation for refined earthquake haz-ard analysis and prediction.     

Studies on seismic source

During the period of 1999-2002, the Chinese seismologists made a serious of developments in the study on seis-mic sources including observations, experiments and theory. In the field of observation, the methods of the accu-racy location of earthquake sources, the inversion of seismic moment tensor and the mechanism of earthquake source are improved and developed. A lot of important earthquake events are studied by using these methods. The rupture processes of these events are inverted and investigated combined with the local stress fields and the tec-tonic moment by using the measurements of surface deformation. In the fields of experiments and theory, many developments are obtained in cause of seismic formation, condition of stress and tectonics, dynamics of earthquake rupture, rock fracture and nucleation of strong earthquakes.     

Research on probability of seismic critical instability on basis of''''''''fracture collusion'''''''' model

Ｒｅｓｅａｒｃｈｏｎｐｒｏｂａｂｉｌｉｔｙｏｆｓｅｉｓｍｉｃｃｒｉｔｉｃａｌｉｎｓｔａｂｉｌｉｔｙｏｎｂａｓｉｓｏｆ＇＇ｆｒａｃｔｕｒｅｃｏｌｌｕｓｉｏｎ＇＇ｍｏｄｅｌＳＨＩ－ＹＯＮＧＺＨＯＵ１）（周仕勇）,ＬＩＮＧ－ＲＥＮＺＨＵ１）（朱令人）,ＭＡ...     

Random stability for lateral vibration on footbridge based on IEVIE–PDE method

The pedestrian-induced lateral vibration of footbridges is essentially classified as a nonlinear stochastic vibration. Accordingly, bridge vibration stability falls within the field of nonlinear stochastic vibration stability. At present, the Lyapunov method is mainly used to analyze such stability. However, this method is qualitative, and it cannot quantitatively analyze the vibration stability probability. In this study, a new analytical method based on a comparison of the input energy and the variation of intrinsic energy(IEVIE) is used to analyze the nonlinear stochastic vibration stability of the lateral vibration of the footbridge. The improved Nakamura model is used to describe the lateral nonlinear stochastic vibration of the footbridge. A combination of the IEVIE method and the probability density evolution(PDE) method is then proposed, in which the IEVIE method is utilized to determine vibration stability. The PDE method is used to obtain the reliability of vibration stability. The proposed method is successfully applied to the Millennium Bridge, and its effectiveness is verified by comparing the Monte Carlo and Lyapunov methods. The proposed method can obtain the dynamic probability of the vibration as stable or instable and provide a reference for quantitative analysis of lateral nonlinear stochastic vibration stability of footbridges.     

Study on the method of optimal location on explosion events at near-source site

IntroductionEarthquake location is one of the inverse problems in seismology. The accurate earthquake source location is the basis of studies of earthquake images, the relation analysis between seismicity and tectonics, and the important parameters of earthquakes. It is also the basic data used to study the space distribution of aftershocks after a strong earthquake. The earthquake location accuracy mainly depends on reliability of the velocity models for the earth(s crust, the reasonable desi…     

Numerical analysis on the influence of rock specimen size on crack stress field

Introduction Earthquakes are excited by dislocations of rocks, which are generated once the stresses on two sides of rocks accumulate to a certain extent. Numerical simulations and rock mechanics ex-periments are two important avenues to explore the rupture processes of seismic faults. Several methods are widely used in numerical simulations, such as the boundary element method (BEM), (Das and Aki, 1977; Fukuyama and Madariaga, 1995, 1998), the finite difference method (FDM), (Madariaga, 1…     

Argument on the magnitude-frequency relation

IntroductionSince the magnitude-frequency relation (1)being proposed and applied to the research of global seismicity by Gutenberg and Richter (1944, 1954), it has been widely used in the practice of seismic hazard prediction and of the research of seismic activity in different tectonic regions of the world ((1) is normally known as the G-R law).While with the increase of observational data of events, much researches show that though (1) can fit data well for events with middle value of magn…     

Research on seismic stress triggering

Introduction What is called seismic stress triggering refers to that stress change tensor produced by previous earthquake projected on the fault plane and slip direction of subsequent earthquakes, taking into account normal stress, pore pressure and friction coefficient, and Coulomb failure stress change DCFS can be obtained. If the direction of Coulomb failure stress changes are consistent with slip direction of subsequent seismic mechanism, e.g., Coulomb failure stress changes are positive…     

Physical background on estimating bvalue

ＰｈｙｓｉｃａｌｂａｃｋｇｒｏｕｎｄｏｎｅｓｔｉｍａｔｉｎｇｂｖａｌｕｅＷＥＩＱＩＯＮＧＨＵＡＮＧ（黄玮琼）ＷＥＮＸＩＡＮＧＬＩ（李文香）ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕ，Ｂｅｉｊｉｎ...     

Preliminary discussion on earthquake predic-tion research Whether it relies on experience or determinacy

ＰｒｅｌｉｍｉｎａｒｙｄｉｓｃｕｓｉｏｎｏｎｅａｒｔｈｑｕａｋｅｐｒｅｄｉｃｔｉｏｎｒｅｓｅａｒｃｈＷｈｅｔｈｅｒｉｔｒｅｌｉｅｓｏｎｅｘｐｅｒｉｅｎｃｅｏｒｄｅｔｅｒｍｉｎａｃｙＬＩＵＱＩＡＯＷＡＮＧ（王六桥）ＳｅｉｓｍｏｌｏｇｉｃａｌＢｕ...     

Advances on Active Tectonics Research

The tectonic movement at human scale has not been fully understood yet, especially for active tectonics, although it is the basis to study natural hazards and environmental variations. Many national and international scientific plans related closely to active tectonics research have been made in the past ten years. This paper briefly summarized the background of the undertaking of active tectonics research, its advances and existing problems, and the key points in its future studies are also pointed out. The emerging of new technologies like the Earth Observing Sys tem, Digital Seismology and so on provides unusual opportunities for tectonic research. It is emphasized, however, that careful analyses and building up of new theoretical frame are sill the key problems for studies of active tectonics, especially for active tectonics in China‘ s conti nent.     

Comment on “A note on the free-surface effect on the topographicaily induced vorticity field in a homogeneous flow” by lee-or merkine

Abstract

MASS LOSS AND EVOLUTION OF O-TYPE STARS. I.A.U. Symposium No. 83. Edited by P. S. Conti and C. W. H. de Loore. Reidel, Dordrecht. (ISBN 90-277-0989-0 pbk) 1979. Price U.S. $31.50.

A MATHEMATICAL INTRODUCTION TO FLUID MECHANICS by A. J. Chorin &; J. E. Marsden, 205 pages, paperback, Springer Verlag. (ISBN 0-387-90406-9 and ISBN 3-540-90406-9) 1979. Price: DM 29—US $16.00.     

Analysis on influence of seismic travelling wave effect on semi-active control for long-span rigid-continuous bridge

Introduction The methods of enhancing ability of bridge to resist earthquake disaster can be divided into two aspects. One is enhancing the resisting earthquake ability from the designing ways; the other is adding control devices on the existing structures to effectively control the seismic responses of bridge from the vibration control ways. The great progress has been made in structure control technique in the last years. It has the advantages of security, validity, economical and wide appli…     

Research on probability of seismic critical instability on basis of “fracture collusion” model

Applying the idea of renormalization group and fractal theory, we analyzed seismic hierarchy feature detailed. Based on the seismogenic model of “fracture penetration”, we built a model of seismic critical instability, deduced its recursion relationship of renormalization, and estimated the probability of its critical instability P. The paper is supported by the Chinese Joint Seismological Science Foundation, Project No. 950085.     

Seismological Research on the Mining Tremors

A sophisticated seismological method has been introduced to the study of mining tremors by the Institute of Geophysics,SSB in cooperation with the Beijing Mining Bureau of NCC.Achievements have been obtained in the following areas:modification of the seismic monitoring system,compilation of a software package for analysis of mining tremors,research on the mechanical model for mining tremors,classification of mining tremors and development of an expert system of tremor prediction.     

Comments on “Core Eigenmodes and Their Impact on the Earth’s Rotation”

Surveys in Geophysics -