Abstract:今年是甘肃昌马7.6级大震发生50周年。我国自办的第二个地震台-南京地震台,正是在那一年兴建的(第一个台是1930年李善邦先生在北京鹜峰建立的)。

Abstract:金咏深先生是我国现代地震学事业开拓者之一,他的早期学术活动不为今人所知。今年七月欣逢南京地震台建台五十周年,在编写南京地震台志时,才略知一二。

Abstract:This paper deals with the seismicity pattern before the earthquake ac-cording to seismological data of China.
The results obtained from this work show that there are three abnor-mal patterns,namely,gap of the seismicities,epicenter shift and fore-sock's belt densely-distributed and the concept of "gap belt of seismicity" has been proposed.Besides,according to the b-value and the energy-releasing curve,it is inferred that the occurrence of the M 8 earthquake was cau-sed by an active tectonic zone with a long time action

Abstract:In this Paper,the term "symmetrical migration" represents the regular su-ccessive migration of earthquakes according to a definite symmetrical figu-re in a definite space domain or on a definite geotectonic background.
The obtained information indicates that the symmetrical migration di-ffers from the migration along a seismic zone.It is an independent migra-tion set composed of four interrelated earthquakes occurred at four nodes of a X-fracture network.The set formed by the four shocks mutually coo-rdinated must satisfy the following three conditions:(1) The four shocks must form a symmetrical or nearly symmetrical quadrangular figure in space.(2) Their magnitudes are nearly the same,the defference does not ex-ceed 0.5.(3) The occurrence time of the four shocks in each set have ce-rtain regularity.In general,it can be expressed as T₄-T₃ ≤ T₂-T₁ or T₄-T₃ ≤(T₂-T₁)+10.
According to the migration sequence and route,it may be classified into three types:The opposite angles type,the sharpbend type and the closed loop type.
For the most part of earthquakes occurred in China can be coordinated into sets,using the "former three shocks "which do not form a set at present,the "three elements"(time,epicenter and magnitude) of the later one can be predicted.
Further,in the light of distribution of "the later shock" that can be predicted at present,we can make a correspondent analysis and form ap-propriate estimation of the trend of the earthquake on a nation-wide scale.

Abstract:In this paper,a physical-mathematical model for the earthquake pre-paratory process is suggested.According to this model,such process inclu-de four stages:dilatation,formation and development of inclusion,fluid diffusin and preseismic instability stages.These stages of the earthquake preparatory process in a cylindrical region along the fault are researched by the method of mathematical physics The computational formula of the duration of every stage is derived from investigqting these subprocesses.The computational results are in agreement with the empirical data of premonitory seismic velocity anomaly.
The problem about velocities of seismic waves in the two-phase media is theoretically studied.The computational formulas of the P,S wave vel-ocities and the velocity ratio are given.Some quantitative results are ob-tained.
Based on the described results some characteristics of the seismic velo-city anomaly before earthquakes,namely,the duration of anomaly,the form and dimension of anomalous region and the amplitude of anomaly,are theoretically explained.
Finally,some factors affecting velocity anomaly are briefly discussed by means of dimensional analysis and analogous theory.

Abstract:In this article the velocities of dashed waves of 5 areas in Ningxia have been determinated by wadati's method.On the basis of the velocities of dashed waves we determinated the seismic source depths related to 1460 times of shock.In the spatial distribution of these depths we find that the depths of seismic source in the region of Ningxia have become deepened gradually from south to north,but there is some difference in several re-gions where the earthquake is centrolized.In the region of Xihaigu the di-stribution of seismic source appears elliptic,and there is an irregular inte-rruption layer in the place of 15-20km,In the region of wuyin there is a source zone which extended northeastwards.In the region from wuzhong to Masanhu a dipping zone deepened gradually is emergent.In the region of Shijushan and its northern area the distribution is continuously la-yered in the main.In the line from Yinchuan to Shijushan there is a cline plane extended northwest,where a small earthquake gap is present.The force source that formed the seismic origin distributions as mentioned abo-ve is discussed in the article too.

Abstract:We called all the higher frequency of aftershocks not keeping the after-shock decay rule is discussed and called an swarm of aftershocks.
In this paper,the aftershock sequences of the three strong earthqua-kes located in Xingtai (邢台)、Haicheng (海城) and Tangshan (唐山) in the latest earthquake active period of Northern China are studied.From ob-served data and some experimints we consider that the aftershock swarm is the effect of the strengthened stress at aftershock region under the ba-ckground of the strengthened regional stess field.the fluctuation of the aftershocks sequences of a strong earthquake can be regarded as a "window" from which the preparing process of a middling-strong or more earth-quake in North China can be found and watched.
The relation between the aftershock swarm and the middling-strong ear-thquakes is discussed from the view of "the field of more than one point",and consider the strong earthquake and the middling-strong earthquake are at dominating and being dominated situation in the regional stress field respectively。

Abstract:大震前地震活动性的研究,人们进行了许多有意义的工作。早在1962年笔者在研究河源6.1级地震和日本伊豆6级地震前的地震活动性时,发现一些大地震前的地震频度与地震总数相关。

Abstract:The historical strong earthquakes and the recent micro ones in the Wei River graben show some characteristics in time-spacial distribution,source mechanism,and in their relations to the fractured structure of this area and the stress field in larger area around.The study of these cha-racteristics indicates that the main area of historical strong earthquakes is just the present quiet area where the stress of seismic monitoring sho-uld be put on.But there are no conditions for generating a strnog earth-quake at present.

Abstract:In this paper,PS reflection was used to determine the depth and fluc-tuation of Moho discontinuity in the local region of the north side of the Yarlung Zangbo River.
A clear PS reflection was recorded in the radial direction of the Ya-dung-Dang Xiong profile the apparent velocity is 8.35±0.28Km/s.
Travel times of pp and PS phases reflected at the same part of the Moho were used to determine the structures of lower crust,the dip of Moho discontinuity is-0.83°-0.84° and its depth is about 68-69 Km.The range of fluctuation of Moho is 120Km and the extent is about ≥ 1Km.The result indicates that fluctuation of Moho is slightly changed and the crust is fundamentally horizontal.The authors recognized that PS reflection could be very useful for the determination of flactuation of Moho and for the study of the inner cru-stal structure.

Abstract:In this paper,the method of calculating Q value with depth in the cr-ust by means of data of near earthquakes is described.
It is found that the relationship Q (z)=26.27z-14.4(z>11Km) may be adopted in Beijing and its adjacent region.The results obtained also show that Q value is 300-400 in the depth from 11-15Km which is the average focal depth in Beijing area,and Q-1000 approaching to the bottom of the crust.

Abstract:In this paper we have obtained the solution of the plane problem whi-ch has two semi-infinite cracks (they are situated on the same line) and is subjected to the stress along the boundaries at infinity whose principal-vector is a constant.We have analysed the character of this stress field:The boundaries of the tension-pressure stress regions and the cracks divide a plane in six parts.These distributions are essentially decided by the di-rection of the principal-vector of that exterior forces.
Since the linear solution and its stability are discussed,it is possible for us to analyse the extended form of the cracks and obtain stronger fr-acture condition than "coulomb's fracture criterion".The approximate ex-pression of the fracture length is obtained.
In all the development process of an earthquake we can assume that the exterior forces are continually strengthened along the same direction by the aid of the geological mechanics.Calculation,however,shows that the elastic deformation has made the direction somewhat deflective,which is related to the locked segment.Hence the developmental process can be di-vided into two phases as the principal-vector attains the particular direc-tion.In the first phase the cracks have no extension.Through calculating the additional stress field with timeparameter,we discuss the changes of the stressfield which are caused by the aforesaid deflection.In the second phase the cracks have extension or the pure shear dislocations at either end of the locked segment take place.We analyse the stress character in the phase with the help of the calculation of additional stress field which is caused by the dislocations.We discuss the relations of the earthquake sequences and the strong earthquake.
Finally,We discuss the plane problem with two semi-infinite cracks which are situated on different lines and obtain the chief results which are similar to what we have said before.

Abstract:A computer program of isoparametric finite element for large elastis-plastis strain was used to calculate the displacement-strain fields of a ho-mogeneous expansive sphere in many-layer medium.The effects of the soft layer on diaplacement-strain fields and precurson of earthquakes were stu-died.Finally,we discussed the problem of obvious seismo-precurson layer.

Abstract:It this paper,based on the data of apparent electrical resistivity ob-served in the regions surrounding some large earthquake (M ≥ 7) epicenters,the influences of rock mechanical properties in the observational region on precursor △ρ_s/ρ_s of apparent electrical resistivity are studied.The resul-ts obtained show that the thickness of quaternary covering soil can abate the precursor of apparent electrical resistivity,and the thicker the quater-nary covering soil,the smaller the value of precursor △ρ_s/ρ_s of apparent electrical resistivity.Moreover,the rocks with loose structure reflect the earthquake qrecursor of apparent resistivity more obviously than that with compact structure.Therefore,the observational stations of apparent electrical resistivity must be installed on the thin soil layer covered the rock fundament with low electrical resistivity.

Abstract:在远距离遥测传输过程,被传输的讯号中断时,PTY-8遥测仪鉴频盘将输出幅度很大的脉冲千拢,严重地损害了记录图的质量,甚至有些已经记录到的地震波形被掩没在讯号中断后出现的高频脉冲干扰中。据此,我们设计了快速自动保护电路。

Abstract:In this paper,the distributive regularity of more than 680 hot springs and the epicenters of 40 great earthquakes of magnitude ≥ 7,the relation bet-ween hot springs of different origins and new tectonism in Shanxi,Gans-u,Ningxia,Sichuan,Yunnan,are statistically discussed.It is found that the great earthquakes usually took place near or in the edge of a locality rich in hot springs.
The authors have preliminarily researched the causes closely related the epicenters to hot springs from the earth releasing energy,tectonic motion and the model of the formation of earthquakes.It is considered rea-lative to thermal stress at depth because underground temperature of a loc-lity rich in hot springs is higher,plasticity of rock is greater and rock is easier to break and it is a regulative unit under regional stress.And owing to the fact that local thermal stress proceeded from the difference of temperature at depth in horizontal direction adds up to regional stress,and tremendous stress is accumulated in the locality where the temperature of rock is lower and its intensity is greater (accumulate unit)。Therefore,the great earthquake occurs.

Abstract:Based on studying the feature of seismogenic structure and the neote-ctonic setting as well as on analysing deep-seated structure conditions of the Easter Yangtze Gorge,some geological structure signs of the weak earthquake are discussed in this paper.
The Yangtze Gorge is referred to a weak earthquake area in accordance with data up to now.The seismic activities in the region mainly occurred on the surface of East Gorge,so the dependence of relations between them is close and obvious in space As these seismogenic structures are located in the neotectonic background of the whole upheaval and merely dissect the upper crust,there are features of weak earthquake with small intensi-ty,low frequency and shallow focus.
In accordance with the seismotectonic relations mentioned above,the signs of geological structure of the weak earthquake in this area may be summarized as follows:
1.The seismogenic structures belong to a fault lying in a shallower layer of the crust,which has had no evident dislocation since Quaterna-ry Period.
2.The regional neotectonic movements are mainly characterized by con-tinual uplift and subsidence of arched flexures as a whole.Usually the broken river terrace,the dismembered denudation surface and the geomorph-ic gradient belt do not appear.
3.The tectonic deformation in the newly-formed sediments is not obvi-ous.It is generally short of Quaternary fold and fault.

Abstract:In this paper we points out that there are three high electrical conduc-tivity anomaly (HECA) belts within Gansu province.One is the DV pat-tern north-east belt of HECA between Jayuguan and Hexibao,the other two are the HC pattern area of HECA in Jingtai and the DV pattern east-west belt of HECA between Dingxi and Tianshui.According to E.C.-Bullar's view,we suggest that their buried depth be from the crust to upper mantle.
In addition,based on the distribution of underground water and hot springs,we analyse the cause of HECA.Consequently,it is emphasized that these high conductivity regions play an important role on the earthquake prediction.

Abstract:In this paper,the short-period geomagnetic events in and around Sha-nxi are analysed.It is found that the directions of variation in vertical component on the south and north sides of the Wei River which is taken as a rough boundary are opposite.It can be inferred that there exists an east-west belt of high electrical conductivity beneath this region.From other characteristics of short-period geomagnetic variations,a rough est-imate of shape and properties of the belt is made.Connecting this belt wi-th that discovered in eastern Kansu,a belt of high electrical conductivity of 1,000-odd km.will be formed.

Abstract:There are two problems in zoning the strong motion area by means of pattern recognition.One is how to decide whether the training set is divi-sible linearly,which is directly related to the problem of convergence of the iteration process.The other problem is the conflicting results of pred-iction that come from the differences of recognition functions which are brought about by the fact that the solution of training is not unique.In this paper these two problems are discussed according to the theory of system of linearly inequalities and a preliminary result has been obtain-ed.

Abstract:一次浅源强震发生后,震区人民的生命财产总会受到不同程度的损失。广大群众由于耽心再次发生同样大的或更大的地震均搬到室外居住。