DAI Weile , WANG Wei , SONG Jungao , ZHOU Yunhao
1997, 19(2):1-6.
Abstract:The seismic data from 1972 to 1992 in North China are used in spacial scanning of seismic risk degree D-value in this paper.The result shows that there are large anomaly zones of D-value around the future epicenter about 3 years before most moderate-strong earthquakes.In this paper,the method using D-value in medium-term earthquake prediction,prediction ability,the relation of D-value to real seismicity and the stability of computation are also discussed.
WAN Yongge , LI Qinghe , LI Hongji , DING Zhifeng
1997, 19(2):7-14.
Abstract:The calculation of the travel time in 3-D velocity structure has been given in this paper.In the process of the genetic algorithms,considering large parameter space in the initial iterations and small parameter space in the final iterations,authors give mutation probability which is a large value in the initial iterations and small value in the final iterations.The formation of the mutation probability is linear and exponential with iteration.It is found that the exponential function is a more effective method.Using the exponentially reduced mutation probability,the hypocenter is obtained through genetic algorithms.The residual of the hypocenter is very small.
WANG Jihua , WANG Liang , SUN Fengmin , JIN Xiaowei
1997, 19(2):15-19.
Abstract:Based on the observations and research results in engineering seismology for many years,the influence of artificial and natural factors produced in the field sampling on the observation of Hg content in soil gas is expounded.A method for getting over the influence factors is discussed.In study of engineering seismology,rational sampling depth and volume are introduced for observing Hg content in soil gas.
1997, 19(2):20-26.
Abstract:In this paper,main compositions of 8 hydrochemical ovservation items in Xiaguan hot spring in 1992 have been analysed and the disturbance factors have also been studied.The results show that radon and air pressure,water temperature and PH values,argon and nitrogen,and CO2 are 4 main compositions which have stronger independence.Air pressure and flow quantity are the main disturbance factors to the chemical compositions.
1997, 19(2):27-33.
Abstract:In this paper,the vertical axis is treated as one of the principal axes of the two-dimensional, symmetric, anisotropic media,in which the structure strike is an arbitrary included angle with respect to another principal axis. In this condition, the entire region is divided into rectangular elements.For the basic equations of the two-dimensional anisotropic media,a total stiffness matrix is composed reasonably, so the coupled finite element equations can be formed byusing Galerkin's finite element method.By solving these equations for the fieldcomponents at each node and on the basis of MOM-method,author evaluates the auxiliary field components on the earth's surface and obtains MT responses such as tensor impedances and so on. In addition, a numerical calculation test for the model which was used in the related reference is carried out.
1997, 19(2):34-40.
Abstract:The Fujian-Guangdong coastal earthquake zone has the highest seismicity level in southeast coastal region of China.The region where economy is flourishing and density of population is very large is the most famous home of foreign residents of our country.Therefore,thoroughly studying the Niushan Island Brother Islets fault zone and its activity has important significance to earthquake prediction,earthquake disaster reduction and seismic safety evaluation of some great engineerings in the region.The study results show that MS≥7 earthquakes will possibly occur along the fault zone in the future.
1997, 19(2):41-47.
Abstract:In the eighth Five-Year Plan period,a new information compostion method called as Information Series Synthesis Method is given through the study of a second order project,85-04-02-01,for short-impending earthquake prediction research.As a part of contents of the works for continuation of the first order project,85-04-02,and pre-researches for project in the ninth Five-Year Plan period,the Information Series Synthesis Method is further perfected and applied to daily prediction work and the primary results have been obtained,This is a significant exploration for closely linking the earthquake study and prediction.
1997, 19(2):48-56.
Abstract:In this paper,through the function transformation of four disaster loss indexes about the dead number,the injured number,destroyed buidings and direct economic loss caused by earthquakes,the standards to distinguish these disaster grades by using different loss indexes are unified.The earthquake disaster grades are divided by the grey cluster method,and the different earthquake disaster situations are compared by the sequencing method of the grey associative degree.The disaster grades of 7 important earthquakes in Chinese mainland from 1966 to 1983 and 17 earthquakes in Chinese mainland in 1995 are divided and their disaster conditions are compared by using the methods.The results show that the methods basically can evaluate quantitatively and accurately the seismic damage situation.
1997, 19(2):57-61.
Abstract:By using the mode recognition method,possible positions of future seismic risk regions have been determined through the comprehensive analysis of seismogeological characteristics in southeast Gansu Province.The results show that the places prone to earthquakes in the working area correspond to the strongly active segments of Holocene faults,thus the reliability to determine the future seismic risk regions is enhanced.
WANG Jun , WANG Lanmin , LI Lan
1997, 19(2):62-66.
Abstract:Based on the laboratory research on seismic subsidence of loess under different seismic loads,seismic subsidence quantities on several loess sites in Lanzhou were predicted.The result shows that there is a certain difference in the predicted seismic subsidence quantities under irregular seismic loading and equivalent sinusoid loads.
JIANG Mei , HOU Weirong , HOU Yuanwen
1997, 19(2):67-72.
Abstract:Distribution of strong earthquakes in and around the Minle basin and relationship between repeated MT observations and occurrence of strong earthquakes are discussed.The results show that systematical changes of apparent resistivity curves correspond to occurrence of strong earthquakes in the region,and ststematical variations of apparent resistivity with different frequency bands are closely related to occurrence of earthquakes with different strengths.
1997, 19(2):73-76.
Abstract:The fractal dimensions of earthquake precursor time series(resistivity and stress)which are gained from Changli ground resistivity station and ground stress station before and after the Tangshan earthquake (from 1971 to 1978) are calculated by the method of phase space reconstruction in this paper.The results show that the attractors of these two time series are of fractal dimension structure and the two different earthquake precursor attractos have the same diagnostic variation.It is also discovered that the ground resistivity is of multiple fractal dimension in different character scale,which is discussed in this paper.
ZHANG Xiuxiang , WANG Xiusheng
1997, 19(2):77-80.
Abstract:The apparent resistivity on the fracture zone of buried fault in the Weihe basin shows always negative anomaly.The amplitude of anomaly increases and outline of fracture zone becomes more clear when the exploration depth is deepened.The linear distribution of anomaly points of apparent resistivity is a criterion for determining the strike of buried fault and evaluating the exploration result.Difference of apparent resistivity on both sides of fault shows the electrical difference of different materials on the both sides,indicating the vertical fault throw.The negative anomaly of apparent resistivity on the fracture zone of fault results from existence of rich underground water.
1997, 19(2):81-87.
Abstract:The main disasters and diseases such as earthquakes,geological hazards,windblown sand,frescoes' and painted sculptures' diseases,damages caused by tourism,harmful effects of human activities etc.in the Mogao Grottoes are summarized.The factors and background causing the disasters are analyzed and the comprehensive countermeasures against diseases are put forward.The results in this paper provide a theoretical and practical basis for the scientific conservation of these grottoes and the restoration of cultural relics.
1997, 19(2):88-93.
Abstract:Rased on activities of faults in Minle-Zhangye basin and around it,space and time of occurrence of future earthquake in the area are predicted.The results show that the 6.5≤MS≤7.0 earthquakes will most likely occur on the western segments of the Yumushan and Hongyabu faults within 50 years.
CHANG Qiujun , HE Genqiao , CAO Chunping
1997, 19(2):94-96.
Abstract:Observation data of gas N2 dissolved in spring water in Wuquanshan from 1983 to 1995 were processed mathematically.It is found that the gas had anomaly before several moderate-strong earthquakes along the east segment of the Mt. Qilian structure zone.In this paper,the mechanism of the anomaly is discussed preliminarily.
Sopyright:China Earthquake Engineering Journal