1991, 13(4):1-13.
Abstract:In this paper,the history and progress of study on stopping phase are reviewed systematically,and the physical mechanism of stopping phases in the source rupture process is discussed.The master-event analysis method and the synthetic seismogram method including stopping phase are discussed in detail.By using the master-event analysis method,the actual data of the Tangshan earthquake are processed,and we get the spatial-temporal picture of the source rupture process during the Tangshan earthquake,meanwhile,the synthetic seismograms including stopping events are calculated.The results show that with taking into account of stopping events of rupture process,the Pwave observed seismograms can be fitted better,the possibility is further confirmed that there existed two stopping events during the source rupture process of the Tangshan earthquake.Finally,the source environment of the Tangshan earthquake and the abdication of adjustment element are also discussed.
1991, 13(4):14-21.
Abstract:Nine samples of hot springs covering the eastern region of Gansu Province are collected and analysed.The measured components include He,He3/He4,F-,Cl-,Li+,He4/Ar40 etc..These items present synchronous anomalies in Qin'an region.Finally,by using a method of factor analysis,the information variation of the samples and components is comprehensively analysed.The result shows that it is possible to exist a buried fault in company with magmatic intrusion in Qin'an-Qingshui region.
1991, 13(4):22-28.
Abstract:In this paper,the authors apply the 3-D finite element method of visco-elastic medium to simulate the effect of some kinds of fault on the stress-strain field of layered medium under the lateral boundary condition of a constant rate of displacement loading,and then proceed to bring to light the effect of faults on station location of apparent resistivity through the relation between the stress-strain field and the changes of apparent resistivity.
The results show that the mutual location between the geoelectrical station and fault,and the mechanical features and the types of fault have important significance to the selection of the place of geoelectrical station.Parallel fault which is seriously broken and wide has some obstructive effect on apparent resistivity information,and compact dead fault,the medial part of vertical fault and the ends of transcurrent fault have enlarging effect on apparent resistivity information.The authors also discuss the effect of two different types of seismic fault on the observation of apparent resistivity,the conclusion is that the dislocation earthquake has stronger precursory information than the slip earthquake.
Wang Junguo , Zhang Shaoquan , Wei Pengfei , Wu Xiaozhi
1991, 13(4):29-34.
Abstract:With the development of the deep-hole seismic network,much significant information has been reflected in the seismic data observed in deep holes.In this paper,the characteristics of seismic waves recorded at different longitudinal depths are analysed and studied;the physical origins for the travel-time difference of seismic waves and the amplitude difference recorded at various longitudinal depths are investigated;the effects of the characteristics for the medium of the station base and its spacial condition (full space or semi-space) on the characteristies of propagation and record of seismic waves are indicated;and then all above-mentioned is explained uniformly by the theory of softcovering effect.The results show that at different longitudinal depths under the earth,ranging from bottom to top until the earth surface,the displacement amplitude of seismic waves is amplified gradually,the travel time lengthened and the period enlarged.The loose deposit overburden in the plain area has the effect of amplification,delay and filter on the seismic waves.The reflection wave propagated downwards from surface can be observed in the holes,therefore,the wave column becomes more complicated.
1991, 13(4):35-40.
Abstract:This paper analyses the characteristics of fixed-point deformation anomaly before the Lancang-Gengma,Yunnan Province,earthquake on Nov.6,1988.The results show that the trend anomalies are characterized by short,anomalous duration time,change rapid,consistent tilt direction in space,1-2 accelerated change stages during the anomalous duration process;the short-term anomalies appeared 2-6 months before the earthquake,with the tilt vector to knot,the direction change and the obvious velocity decrease;the direction of deformation anomaly has some contact with the epicentral direction.
Huang Xuexiang , Ding Jianhai , Zhang Shulan
1991, 13(4):41-48.
Abstract:This paper systematically summarized a prediction method of daily low-point displacement of geomagnetic vertical component,and the relation between the low-point displacement anomaly and the strong earthquakes.It introduced emphatically the geomagnetic low-point displacement anomalies and the short-term trend judgement before the TianZhu M=6.2 earthquake of 1990.The results show that this prediction method can make short-imminent prediction not only for M ≥ 6 strong earthquakes,but for some moderately strong earthquakes in master monitoring areas.
1991, 13(4):49-53.
Abstract:This paper analysed the data of repeated gravity measurements in 1976 Longling earthquake area.The result shows that before several strong aftershocks occurred in the earthquake area,the variation of gravity measurement appeared obvious process of increasing and then decreasing,and after aftershocks,the gravity value recovers.Finally,the features of the gravity variation are also discussed.
1991, 13(4):54-60,97.
Abstract:Zhengyiguan fault belt crosses the northern area of Helanshan mountain,and it is a regionaly great fracture with a long-term activity.Based on the interpretation of air and satellite photoes at a largescale,field investigation data and 14C dating,this paper discusses and analyses the plane distribution range,active way and active intensity since Quaternary,the latest active time and paleoearthquakes etc.of this fault belt.The newest activity of Zhengyiguan fault belt is intensive and obvious.Since Quaternary,the fault shows apparent left-lateral slip.The faulted geomorphology shows the maximum distance of horizontal dislocation is 18 00-2000m,and the minimum is 10-20 m.There exist two paleoearthquake traces at Maohudugeyinggou and Putaoqnanzizou,it is estimated that the paleoearthquakes occurred about 6000 years ago.
1991, 13(4):61-68.
Abstract:In this paper,by using the revised CORA-3 and weighted Hamming methods of pattern recognition,based on the analysis and study of geological,geomorphological,geophysical and seismological data in Qinghai area,the M6.0,M6.5 and M7.0 potential earthquake source zones are divided respectively in this area.The confidence level for whole recognition and danger probability for each potential earthquake source zone are given quantitatively.The M6.8 Tanggula earthquake on Nov.5,1988 and the M6.7 Mangya earthquake on Jan.14,1990 are all within the potential earthquake source zones divided by this paper.
Guo Zengjian , Qin Baoyan , Li Geping
1991, 13(4):69-69.
Abstract:1.厄尔尼诺的出现可能与地球自转速度加快,赤道带鼓起,地壳孔隙加大,热物质易于逸出,从而加热海水所致。但海水加热有一时间滞后,故厄尔尼诺出现时间在地球自转加快转为减慢之时。减慢的原因是软流圈物质在地球自转加快时向赤道方向运移所致。
1991, 13(4):70-74.
Abstract:临沂台深井电阻率观测始于1979年7月。4口观测井呈东西向等间距排列,间距为7米,井深30米,供电、测量电极均置于井底。用DDC-2A型电子自动补偿仪测景电位差,用50mA的毫安表读取供电电流。
1991, 13(4):78-81.
Abstract:1989年兰州地震研究所承担了嘉峪关市抗震防灾规划编制的基础研究工作。
Li Zhiping , Wu Peizhi , Jing Kaixian , Cheng Shangqing
1991, 13(4):82-83,88.
Abstract:蚌埠电磁波台始建于1984年10月,1986年正式观测,目前已有近五年的连续资料。该台地理坐标为东经117°18',北纬30°54',台基为花岗岩。记录器为DJ-1型地震记录仪。
1991, 13(4):84-84.
Abstract:全球强震活动多集中在北纬35°-45°地带,这种明显的特征早已为国内外学者所关注。然而南纬35°-45°地带地震活动性则相对不高,其原因目前还未见报导。
1991, 13(4):85-88.
Abstract:利用震源机制资料研究现代构造应力场是目前普遍使用的方法,它是研究地壳应力场和构造形变的有效途径。
1991, 13(4):89-96.
Abstract:The classification of various ground fissure disasters,and the preliminary studies on the causes of various ground fissures were made on the basis of comprehensive research of ground fissures in Xi'an city.The macro-distribution of ground fissure disasters in China was mapped briefly,but more detailed in Fen-Wei Basin,where the fissure disasters are severe.The tasks on ground fissure research were put forward.In theory,the special laws should be studied,about how the ground fissures are unstable,propagate and stop in homogeneous,soft shallow soil-layers of the earth.In practice,the practical techniques should be provided to protect environment,resources and city plan from damage caused by the fissure disasters.Furthermore,some basic information may be given to benefit the earthqauke prediction research and geothermal energy development.The tasks should be undertaken by a new branch of earth scienees-Groundfissurology,which will be born in the beginning years of IDNDR (International-Decade for Natural Disaster Reduction).
Sopyright:China Earthquake Engineering Journal