• Volume 8,Issue 3,1986 Table of Contents
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    • THE FURTHER STUDY AND DISCUSSION ON THE ANOMALIES OF SEISMIC WAVE VELOCITY

      1986, 8(3):1-11.

      Abstract (567) HTML (0) PDF 760.28 K (497) Comment (0) Favorites

      Abstract:It has been going through a repeated process from hot to cold to apply seismic velocity ratio to predict earthquake.It is attentive how to treat actually it.
      In this paper we cleaned up seismic velocity ratio method and gave preliminary conclusion.
      First,we summed up briefly general situation of seismic velocity ratio before and after some moderate and strong earthquakes in China in recent years.There are seven earthquakes which were predicted,twelve earthquakes which found anomalies after earthquakes and two,not any anomalies even after.
      Secondly,several problems of anomalous seismic velocity ratio have been discussed by means of natural earthquakes data.The paper considers that recent denser regional transmission networks help increase favourable condition in observational precision and the error may not conceal the anomaly.The examples predicted before earthquakes have been presented,especially,two variation diagrams of seismic velocity ratio in two earthquakes which occurred at same situation during two-and half years are quite similar.We considered that the thoughts about seismic velocity ratio anomaly ought not entirely to be abandoned.We must note its directional effect,i,e,anisotropic effect when the Wadati method is used.In fact,it is not suitable when the Wadati diagram is calculated with data,the epicentral distances of which are more different,so that if the method of the single station and of many stations is applied with comparision,the effect may be better.The anomalous time appeared and reactive level amongfar and near stations,higher and lower points,variable anomalous regions,must be noted.
      Finally,the variations of seismic velocity by blasting data before and after Haicheng M 7.3 earthquake on Feb.4.1975 are studied.The tendency of variation of imaginary wave velocity in Dandong station from 1972 to 1980 is as same as those of natural earthquakes.The level of average seismic velocity ratio after the main event is much lower than that before.The tendency of variation among Yingkou station,Jinzhou station and many other stations are analogous.(S-P) residuum curve of Dandong station shows that the theoretical value before shock is much lower and higher after shock.The relative variation of P,S wave in|Yingkou station is falling Jrom higher value before shock and the level is lower after shock,and the variation of S wave is large.We found that the tendency of variation of P-travel time residue between Yingkou and Jinzhou stations is oppsite.
      From the foregoing data and analysis,we don't think that it is suitable to refute velocity ratio lightly.If we improve the condition of observation,strengthen study of its physical substance,especially,and persist in precursor practice,sum up and study continuosly,a new breakthrough is prossibly made.

    • THE DISTRIBUTION OF FOCUS DEPTH IN GANSU REGION

      1986, 8(3):12-19.

      Abstract (531) HTML (0) PDF 545.00 K (732) Comment (0) Favorites

      Abstract:More than 3000 small earthquakes in Gansu region from Jan.1977 to uly 1984 were relocated with layered crust model.It could be seen that:
      1.These events are located commonly in upper crust less than 15Km deep,concentrating mainly on three layers near 1.5Km,7.5Km and 11.0Km deep,respectively;
      2.The distribution features of foci,such as layers divided,the active evel of upper layer and "source" depth of seismic activity etc.,relate to great historical earthquakes,most of which are located about 15Km deep,fracturing the media close to 40Km deep;
      3.The magnitude of moderate and small events show no change with the depth of earthquake sources.
      Finally,it is disscussd the affection of crust model used in location to the result of depth determination.

    • THE NUMERICAL SIMULATION OF “STRESS WINDOW”

      1986, 8(3):20-27.

      Abstract (537) HTML (0) PDF 518.73 K (559) Comment (0) Favorites

      Abstract:"The stress window" in subside fault block of central Hebei before Tangshan earthquake is simulated by means of the planestrain finite element method,Three.questions under study:(1) the relation between high stress area and the direction of principal stress and the value of Young's modulus;(2) the relation between high stress area and the value of principal stress and boundary condition;(3) the appearance of dynamic process and disappearance of stress window effect.

    • THE APPLICATION AND SCATTERING EFFECT OF SEISMIC WAVES ON SURFACES OF ARBITRARY SHAPE

      1986, 8(3):28-39.

      Abstract (528) HTML (0) PDF 703.38 K (892) Comment (0) Favorites

      Abstract:An improved integral equation method is applied to solve two scattering problems.(1) Under acoustic approximation,plane P waves are scattered by three-demensions surfaces of arbitrary shape in a half-space.(2) Plane SH waves are scattered by infinite elastic cylinders having arbitrary cross section in an elastic half-space.Numerical results of scattering for different geometries are presented.Agreement with known analytical solution for some special geometries is excellent.

    • THE ANOMALIES OF WATER LEVEL IN HAN NO.1 WELL BEFORE IMMINENT EARTHQUAKES

      1986, 8(3):40-44.

      Abstract (553) HTML (0) PDF 328.22 K (458) Comment (0) Favorites

      Abstract:This paper holds that water level varies in Han No.1 well because of sea tide and air pressure.It is of significance to find precursory informations in predicting earthquake from the water level value when the interference is eliminated.

    • THE MULTIPLE ANOMALOUS INDEXES OF GEOMAGNETISM AND ITS APPLICATION IN EARTHQUAKE PREDICTION

      1986, 8(3):45-49.

      Abstract (460) HTML (0) PDF 323.18 K (779) Comment (0) Favorites

      Abstract:In the recent years,on the basis of earthquake prediction by means of geomagnetic method of characteristic,two methods and their indexes of prediction have been dealt with.They are the methods of the anomalous time of crossover of "27 days of slipping error for Z component and vector T".In the normal case,the average slipping error of 27 days of Z component and vactor T of geomagnetism ΔZi ang ΔTi can skip irregularly.But in this region,before the middle and strong earthquakes,ΔZi>0.2 NT,positive anomaly is shown continuously;ΔTi<-0.1,negative anomaly is shown.If the anomalous days of ΔZi and ΔTi are Δt ≥ 14 days,the occurrence day of the middle and strong earthquakes in coming days,according to the anomalous time of crossover method,are t0=nΔt±1day,in the monitoring region of this province.In the formula,n=1,2.
      In the past two years of earthquake monitoring and prediction,the three methods,as are mentioned above,were used to make a good prediction both of Wuzhong earthquake of M=5.1 in 1984 and Tanchang earthquake of M=5.0 in 1985.So a comprehensive analysis of the three methods mentioned above can not only help decrease the pseudoprediction and improve the ability of judging anomalies and predicting earthquake but also can shorten the earthquake occurrence day,from month's predictionto day's.
      K,the slope of geomagnetic characteristics is considered to reflect the physical process of the changes of underground medium structure and electrical conductivity.The average error of slipping of 27 days for Z component and vector T can eliminate the solar cycle impact and give a prominent plaee at depth.As for the method of crossover,there may exist some.rhyme to work together,which is still in the course of research.

    • THE STUDY ON FRICTIONAL SLIDING CHARACTERISTICS OF GOUGE OF HAIYUAN FAULT

      1986, 8(3):50-54.

      Abstract (566) HTML (0) PDF 340.73 K (736) Comment (0) Favorites

      Abstract:The experimental study on frictional sliding characteristics of 13 kinds of gouge in 5 points of Haiyuan fault was made by double shear test method.The experiments show that the existence of Haiyuan fault gouge is helpful to remove the stick-slip and to increase the frictional strength.Here are the average of friction coefficient of gouge in 5 points:Jingtai 0.760,Hasishan-0.728,Dagoumen-0.669 Ciergou-0.644,Caixiangbao-0.684.

    • ON CHANGE OF FORCED DIRECTION OF LAND MASS

      1986, 8(3):55-63.

      Abstract (601) HTML (0) PDF 593.98 K (770) Comment (0) Favorites

      Abstract:Basing on synthetical analysis for a lot of geological structures,observation of ground-stress and ground distortion,and explanations of focal mechanism,the author considers that forced form and forced direction of land mass are changed in both geological age and recent time.Without obstruction and influence of other factors,in the northern hemisphere,at least in middle-low latitudes area,in a single tectonic movement,the direction of compressive stress is changing according to the law SN→NE→NW→EW,it is synchronised with changing of uniform,acceleration and deceleration of speed of Earth's rotation.Since Jurassic period,due to rapid deceleration of Earth's rotation,EW-direction compressive stress is getting stronger.By all above reasons,the conclusion is that the cause,making change of forced direction of land mass,may be related with the change of Earth's rotation rate.

    • STUDY ON THE CRUST STRUCTURE IN NORTHWESTERN CHINA BY MEANS OF RAYLEIGH WAVE SURFACE

      1986, 8(3):64-70.

      Abstract (532) HTML (0) PDF 395.85 K (546) Comment (0) Favorites

      Abstract:The lamellar models of the crust structure of three profiles are achieved in this paper by means of the reverse of the velocities of Rayleigh wave swarms from Kashi to Gaotai and the phase velocities of Rayleigh wave from Kashi to Urumuqi and from Urumuqi to Gaotai.The results show that the frequency curves of scatterness for the three profiles and the crust structure are different each other,which means there is a very obvious transverse variation of the crust structure in Northwestern China.

    • RELATIONS BETWEEN THE PROPERTIES OF SOIL LAYERS AND THE SHEAR WAVE VELOCITIES

      1986, 8(3):71-78.

      Abstract (568) HTML (0) PDF 514.86 K (1078) Comment (0) Favorites

      Abstract:In the paper,the author,according to the data of Xi'an,Xuzhou,Anshan and other places,has applied the multivariate step-by-step regression analysis and the deciding method of nonlinear model parameters to analyze comprehensivly the relations between the shear wave velocities and the depth and indexes of physical and water properties of soil layers,and contrast the relations of one region with other's.The result that the depth and the index of liquid affect the shear velocity is concluded.And the author states that the deciding method of nonlinear model parameters can raise the precision of empirical formula of Vs.

    • THE RESEARCH ON THE ACTIVE HAIYUAN FAULT IN CHINA

      1986, 8(3):79-89.

      Abstract (576) HTML (0) PDF 656.08 K (574) Comment (0) Favorites

      Abstract:The 1920 Haiyuan earthquake (M=8.5) formed a new surface left-late-ral rupture zone along the Haiyuan fault.Its length is about 215 km.The rupture zong consists of seven discontinuous echelon fault segments.The maximum horizontal component of the displacement along the rupture zone is 17m,the average displacement is 7.07 m,and the maximum verticl component of the displacement is 5 m.The discontinuity of the displacement distribution along the rupture zone corresponds with the discontinuity of the fault's trace.
      Since Holocene,5 great earthquakes with magnitude about 8.5 have occured on the Haiyuan fault.Except for the 2nd event,all were dated by Lanzhou University with 14C:Event Ⅰ is 9360±75 yrs B.P.;Event Ⅱ 7830 yrs B.P.(insertion);Event Ⅲ 6300±70 yrs B.P.;Event Ⅳ 3680±60 yrs;Event Ⅴ less than 200 yrs B.P.(ie 1920 Haiyuan earthquake).The recurrence intervals of events increased progressively,and the average recurrence interval was 2325 yrs.The offset of the Haiyuan fault in the Late-Pleistocene was about 500m;since the late period of Late-Pleisto-cene,200m;and since the Holocene it was about 50m.The average slip rate is about 5mm/yr.
      This paper makes an exhoustive study in the following aspects 1.the fracture zone of the 1920 Haiyuan earthquake (M=8.5);2.the Holocdne prehistoric great earthquake on the Haiyuan fault;and 3.Late-Quater-nary faulting on the Haiyuan fault.

    • COMPARISONS BETWEEN THE ERTAI FAULT AND SOME TYPICAL STRIKE-SLIP FAULTS IN THE WORLD

      1986, 8(3):90-97.

      Abstract (480) HTML (0) PDF 881.51 K (735) Comment (0) Favorites

      Abstract:本文对比了可可托海-二台断层与北安纳托里亚断层和圣安德列斯断层,指出了它们在断层运动性质、大地震活动、断层的组合特征以及走滑断层的典型构造地貌等方面都很相似。但是,由于它们所在大地构造部位不同,像二台断层等大陆内部走滑断层的规模一般都小,运动速率较低,大地震复现周期较长;板块边界走滑断层普遍表现为规模大、运动速率高、大震复现周期短的特点。

    • >短文
    • DISCUSSION OF ANOMALOUS CHANGES OF RADON IN THE UNDERGROUND WATER AND ITS MECHANISM BEFORE THE EARTHQUAKE OF M=5.5 IN WUWEI

      1986, 8(3):98-101.

      Abstract (597) HTML (0) PDF 281.22 K (578) Comment (0) Favorites

      Abstract:1984年1月6日在甘肃省武威旦马——西营地区(N37°59,E102°10')发生了一次5.5级地震。震中位于龙首山——冷龙岭——青石岭北北西向一级隆起带的东缘与武威——中宁——中卫东西向构造带北缘的交汇部位。

    • THE CORRELATION BETWEEN THE FORCED COMPONENTS OF INDUCTANCE STRESS AND THE SUSPENDED COMPONENTS

      1986, 8(3):102-107.

      Abstract (542) HTML (0) PDF 366.40 K (503) Comment (0) Favorites

      Abstract:在电感法地应力观测中,井下受力元件探头是否受到了与地应力变化无关的外界干扰因素的影响,是人们关心的问题,至今仍未得到完全满意的结果。

    • THE-RELATION BETWEEN EARTHQUAKE AND TRANSFER FUNCTION ANOMALY OF SHORT CYCLE IN GEOMAGNETIC STAION IN URUMQI

      1986, 8(3):108-110.

      Abstract (515) HTML (0) PDF 176.91 K (536) Comment (0) Favorites

      Abstract:本文分析了乌鲁木齐地磁台的急始型变化事件的资料,发现1983年乌鲁木齐地区发生的三次M ≥ 5级的地震中,有两次与地磁短周期变化存在着联系。

    • >报导
    • PRELIMINARY INVESTIGATION AND RESEARCH ON ACTIVE FAULTS IN EASTERN SECTOR OF THE NORTH FRINGE FAULT ZONE OF AERJIN MOUNTAINS

      1986, 8(3):111-113.

      Abstract (529) HTML (0) PDF 212.90 K (461) Comment (0) Favorites

      Abstract:1984年,作者对阿尔金北缘断裂带东段(甘肃省境内部分)进行了以古地震为主要内容的活断层考查和研究。

    • THE FRACTURE BELT OF GULANG EARTHQUAKE ON MAY, 23 IN 1927 IN GANSU PROVINCE

      1986, 8(3):114-115.

      Abstract (723) HTML (0) PDF 178.67 K (668) Comment (0) Favorites

      Abstract:1985年6月以后,我们对古浪大地震进行了比较全面的室内分析和部分野外研究工作,对于地震断层的认识有了较大进展,因工作还在继续之中,这里仅将某些进展作一简要报导。

    • THE EARTHQUAKE OF M=4.6 ON DEC. 7, 1984 IN MANPO, TIANZHU

      1986, 8(3):116-116.

      Abstract (525) HTML (0) PDF 83.16 K (528) Comment (0) Favorites

      Abstract:1984年12月7日天祝幔坡发生了4.6级地震。宏观震中位于天祝县哈溪区幔坡南。1.烈度及等震线五度区长轴方向为北西西向,沿雷公山构造带展布,长55公里,宽20公里(图1)。

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