Abstract:On the basis of the interlayer discouple model provided in 1979,we further demonstrate the various kinds of discouple forms,which occur between the granite,layer and the basalt layer.These various disco-uple forms are caused by various tectonical movements such as depression,uplift and differential movement of upper mantle.We also.discuss the inf-luence of the discouple phenomena on the occurrence of great earthquake.We demonstrate the existence of the interlayer discouple phenomena by means of the non-symmetric spatial distribution of bigger aftershocks which occurred after the great Haicheng and the Tangshan earthquakes,Those great earthquakes belong to strike slip type,and their dip angles of faults are nearly vertical.
We use the discouple phenomena to discuss the gravity adjustment process in a source volume,which occurs immediately after a gerat earth-quake.The gravity adjustment process can be used to explain that the trends of the aftershock fault plane are more scattered,the dip slip displace-ments of aftershocks are markedly bigger than that of the mainshock,and the aftershocks with dip slipping distribution mainly in the depressed region,which can be observed in the epicentral area and nearby.

Abstract:Based on the analysis of characteristics of aftershock activities in Ta-ngshan,the authors think aftershock activities in Tangshan can be fallen into four stages and three subregions.In this paper the authors also discu-ss the relationships between these characteristics and the geological struc-tures,the structure of depthin seismic focus area,and the characteristics of ground deformation before and after main earthquake.Finally,the aut-hors point out that new distribution of stress field after main earthquake and dilation-flowing fluid theory can regarded as a physical interpretati-on of genesis of Tangshan a ftershock.

Abstract:The Haicheng earthquake of magnitude 6.0(May.18,1978) took place in the aftershock region of the great earthquake (Feb.4,1975,M_s=7.3).In comparison with the anomalous changes before the great earthquake,the middle-term anomalous change in crustal deformation,gravity and region-al seismicity were observed,but there was a litter shor-term anomaly and no foreshock before the occurrence of Haicheng earthquake of 6.0.

Abstract:In this paper,based on the abundant seismic facts,the abnormal fea-tures of hydrogen sulfide in ground water immediately before the occuran-ce of moderate and strong earthquakes in the Tianshan seismic zone are described.A preliminary discussion on the seismic precursory mechanism of underground gases is made.It is noted that,before moderate and stro-ng earthquakes,as a general rule,abnormal changes with hydrogen sulfi-de for a short period of time take place.Mutation phenomena immediate-ly before earthquakes are also obviously observed.Characteristics of hyd-rogen sulfide during the period immediately before earthquakes are as fol-lows:the suddeness of dynamic process (pre-release of stress strain ener-gy),the mutation characteristics of gas amount increase and the short duration of the abnormal stage.Besides,here also an analysis for the sta-te of subjection to forces and the abnormal characteristics of the precu-rsory near fields and far from fields in various stages of earthquake preg-nancy is made.It is considered that the accelerated creep slipping and the appearance of microcracks prior to that of main cracks and the propaga-tion of supersonic vibrations and lowfrequency deformation waves produc-ed therefrom is the main reason for the universal increase in the concent-ration of hydrogen sulfide,radon and other gases in ground water shortly before earthqukes.
In recent years,hydrogen sulfide has become one of the main indices used for predicting earthquakes,and good results have been obtained.

Abstract:In this paper a concept of "Seismic Situation Field" is Suggested It is based on the synthetic analysis,for seismic situation and trend of Gansu from many factors Such as seismic time-space relationship under general condition,seismic back ground in China or in the world,sun-earth physics and so on.

Abstract:Based on the method "from static to motion" and "from surface to dep-th",this paper analyses the geophysical,geochemical,geological and hist-orical material in the continent of China.Seismicity is connected with motions in the depth of eareh.It is suggested that active regions of strong earthquakes M≥6 are under the control of lithosphere thickness;the fault only occurred at the some thickness of lithosphere controls the position of epicentre.As the material activities of asthenosphere are rela-ted to the history of neighboring plate action and the active region of co-nvection cell changes with time,in the seismicitive region changes will take place.

Abstract:From the Point of view of the focal mechanizm and behaviour of grou-nd crack,the component of right-lateral shear strike slip was dominant and at the same time with dip slip during Tangshan earthquake.This sho-wed that the event had occurred by reason of horizontal and vertical force.Inthis paper the authors use three dimensional finite element method to compute the stress field of Tangshan area.It is believed that there are two kinds of distributive force:body force and surface force.And the latter force may be classified into horizontal direction and vertical direction.Horizontal stress field changes with the depth,and maximum horizontal compressive stress is equal to 3 times of hydrostatic pressure,the depth being equal.Its orientation is N85°E.The vertical stress is equal to 1.2 times of hydrostatic pressure results of computation are in the main con-sistent with the occurrence of the event.Tangshan earthquake occurred per-haps by reason of both horizontal stress field and vertical stress field,the former being dominant.

Abstract:In this paper the space-time-intensity distributional pattern of the moderate and small earthquakes before the strong earthquake occurred du-ring the peak period of the fourth active stage in North China is analysed It is found that the regional seismicity before each strong earthquake occ-urence with magnitude m≥7 undergoes a similar variation which is called the developmental porcess at various stages of strong earthquake.The peak period of seismicity in North China consists of such developmental proce-sses.On the basis of the similar pattern of seismicity and characterist-ics of related energy ratio in such processes,the developmental process of strong earthquake in North China can be divided into three different peri-ods:
period A-the preporative period;
period B-the severe Period;
Period C-the immediolely Period.
The characteristics and some regularies of the seismicity during these Periods show the stress and strain variation of the ground medium in North Chinn and coincide with the present concepts about the fracture mechanism.T-herefore it is considered that the development of strong earthquake is d-ependent on the action of the regional stress and is related closely to the active variation and progress of regional moderate and small earthquak-es.A simple model of the earthquake development——the stop-Pass model——is proposed·The research of the characteristics of seismicity and divis-ional indications by stages in the developmental precess of earthquakes in North China may give a clue to predict the strong earthquakes in this re-gion

Abstract:After the preliminary study on certain features of seismic activity of the Alonggangri-Himalaya earthquake zone,this paper presents that the energy which is equivalent to an earthquake of M=8 has been accumu-lated in this zone and judging from the seismic active cycle and trend of removing,there will be possibility of the danger to burst forth an earth-quake more than M=7 around 1985 in its east.

Abstract:This article gives a detailed discussion on the extension of the fault zone along the north fringe of Aerjinshan and its basic features,horizon-tal slide,the attribution of the fault zone as well as its relation to earth-quake activities.The authors indicate that fhe fault zone along the nor-th fringe of Aerjinshan has a long active history,that it has a hori-zontal slide feature whirling about to the left,and that it is a deeper and bigger fault zone cutting crust.The fault zone do not turn at to the southeast after crossing Daba,but it goes on lengthening towords the east till Kuantanshan mountain region,inserts into the Jinta basin and disappears.The fault zone is a transform fault with the maxium distance of horizontal slide to the left up to 120 kilometres.Therefore the active strength is not great since Holocene epoch,and it is a characteristic cre-ep.And the frequency of earthquake activity of the fault zone is vather low.It is only possible for middle-strong earthquakes to take place.

Abstract:In this paper,based on the data of virtual investigation,the author has discussed the characteristics of deformation band and earthquake frac-ture of Gulang earthquke in 1927 and analysed the geotectonical back-ground of this earthquake.The author helieves that the occurrence of Gulang earthquake in1927 Was the result that the fracture band of Tazhuang-Huangcheng andthat of Wuwei-Tianzhu were in activity at the sametime.And based no the analysis of their rupturing way,the mechanics model of fragmentation massif movement has been made.

Abstract:In the network of the transfer of tele-communication of seismological stations,besides the computer equipment,there are also some seismo-logical speical equipments such as earthquake triggers,remote coding units,SZ-3 reproductive locating installation and SC-60 light oscil-loscopes.These equipments must be connected to the computer through interfacing circuits.And these interfacing circuits are devised by the network users themselves.Therefore,in the course of devising and connection,we must pay attention to the relative convention of the computer interfacing.Otherwise,not only the reliablity of the special epuipment will be influenced but also the reliablity of the whole sys-tem of the computer.In this paper,the author discusses briefly some problems which must be solved in the connection of seismological speci-cal equipments and the computer system.and the author also proposes some concrete methods which may serve as the reference for connec-tion and adjustment.

Abstract:There were few and small earthquakes occurred in the history in Ren-qiu oil-field area.The water injection began to be made in December 1976 in this area.During the period of eight years before the water injection,no microearthquakes were recorded at all,but three months after the water injection,earthquakes occurred.With the inerease of Water-injecting amount,seismic activity increased.Up to now there have been four felt earthquakes occurred in this area.The features of the seismic activity are:in the period of one to three months after second order difference △²y_i(being positive value) of the water-in-jecting amount reaching a high value,earthquakes occurred;△²y_i was related with seismic energies;the distribution of epicenters was con-troled by the water-injecting well position;b value of the earthquake sequence was 0.65;and both first motion senses and ratio of amplitu-des at a single station were relatively consistent.The preliminary stu-dy shows that rocks of this area are porous rocks and have more frac-tures,and that the water injection made the pore pressure increase and lowered the frictional resistance at fault surface so that the stre-ss accumulated in the oil-field crust was released by earthquakes.

Abstract:Through the observation and analysis of the ground mierotremors of Tianshui city,it is shown that there are many factors which influence the amplitude of microtremors.The amplitude of the microtremors changs wi-th the topographical and geomorphoiogical conditions.The horizontal mic-rotremors evidently appear to have a predominate direction,which is con-strained by the surrounding topography and geomorphdogy as a whole,and the effects Of the local site conditions on it is secondary.
Some variations of the spectrum characteristic of the ground microtre-mors appear only in the large area,and the spectrum character is cons-trained by the situation of the area geology and new tectonic motion.The resulting spectrum characteristic of the microtremors are the superposi-tion of the effects of the local site conditions and the influences of the area background.
The relationship between the characteristics of the ground microtre-mors and the strong earthquake ground motions is an important research theme on the study of field earthquake ground motion in future.
According to the predominate period and aspect of the spectra of gro-und microtremors,We have divided Tianshui city into some microzones.

Abstract:1976年8月23日松潘、平武之间发生了第二次7.2级地震。震前我们曾根据地形变资料作了预报,现分述如下。

Abstract:鉴定地质构造带的活动性,大地测量是一种重要手段。确定了活动地点,加密观测周期,以了解它变化的频度、幅度、程度,是继续不断地活动,还是间歇性地活动;是小幅度地蠕动,还是大幅度地移动;据此来预报地震、研究地震,亦是当前国内外地震界大力开展的一项重要工作。

Abstract:北京市跨八宝山断裂的短水准观测台有两处:一是国家地震局分折预报中心的固定观测台(原属北京市地震队),二是国家地震局地震地质大队的流动观测台。两台在1975年出现的短水准突出变化均被认为是唐山大震的前兆^{[1][2][3][4][5][6]}。

Abstract:我国著名的甘肃玉门油田自开采以来,曾发生过地震也发生过滑坡现象,为监视该区的地壳运动,国家地震局第二测量大队自1970年起在该区布设有玉门市环、老鸭支线等进行垂直形变测量,并于1973年、1979年、1980年进行了重复测量。测量的结果表明,该区垂直形变表现为上升趋势,局部地区隆起显著。本文根据我们的现场调查和实地考察对油田隆起的原因作一些探讨。

Abstract:1920年海原大地震因其强度高、震级大、破坏重、影响范围广而闻名于世,成为研究近代大陆地震的重要震例之一,常有中外学者问津。

Abstract:众所周知,太阳系有九大行星。当地球和其它行星运行到太阳同一侧,最外两颗行星与日心的连线夹角最小时,叫做九星联珠,我们简称为甲型联珠。