Abstract:In the earthquake prediction.people not only expect to observe direct-ly the change of source,but also to do the practice of observational method much easier.At the same time one requires the disturbance factors are small.This paper discussed the top case of shallow great earthquake.According to practical data,the information of precursors is very obvious in this depth It is an advantageous layer for observing precursors.Because the source of shallow great earthquake is located in the granite layer,the top of source is between the bottom of deposit layer and the top of granite layer,about 4-8 kilometers from surface.In such depth,the confining pressure is low,therefore,the dilatancy,the stable sliding on source fault plane and the fluid move preceding great earthquake are very obvious,but the disturbance from earth surface is not large in this depth.
On the other hand,an anomaly low resistivity layer,which contains much water with high temperature and certain pressure exist between the granite layer and deposit layer.In some places of the layer the fluid is in a superheat state-an unstable state,when some changes from the source arrive there,the superheat fluid will explode.Thus it will lead to the amplification of the message from the source and to sudden change of precusor.Therefore,we call it precusor abvantageous layer.In future,it is very important to put the instrument of observation in such a layer for measuring the message from the source.

Abstract:After the Liyang Earthquake (M_s=5.5) of April.22.1974,networks have been established in the epicentral area and its adjacent region for observing various possible forerunners,including seismic activity,crust deformation,parameters of underground water (Radon content,water le-vel,flow),geomagnetic and stress field variations.Because of these net-works some continuous data were obtained before the Liyang Earthquake (M_s=6.0),the more reliable ones of them have been collected basically in this paper.A preliminary study shows that the preparatory process of the Liyang Earthquake (6.0) can be divided into three stages:the 1^st stage began from early 1978 and is called medium-term anomaly,the 2^nd stage,called short-term anomaly,started in May,1979,the imminent anomaly (the 3^rd stage) appeared half a month before the earthquake.Majority of the anomalies appeared at distances of about 100 km from the epicenter,and a few between 1-200 km.Macro-phenomena (anomalous behaviour of animals,changes in parameters of underground water and so on) appeared near the epicentral region.
The authors suggest that in order to predict moderate earthquakes,it is very important to identify the anomalous characters of each stage and to study the geological structures in the vicinity of the observing points at which the anomalies appeared.

Abstract:In this Paper the dynamical characteristics of underground water an-omaly in the time and space domain before and after Songpan-pingwu ea-rthquake are briefly described on the basis of comprehensive practical da-ta.Preliminary discussion on these characteristics according to the funda-mental principles of rock mechanics is given.It is pointed out that vario-us phenomena of anomaly are related to the mechanism of anomaly form-ation in the different stages of earthquake pregnancy.It may be referential in earthquake prediction,especially the short-range forecast.

Abstract:In this paper the main characteristics of the small earthquake swar-ms in the Luchuan have been investigated by comparing with the fore-shocks of the Haicheng earthquake (M_s=7.3).It is found that seis-mic activity process of the small earthquake swarms may be divided into two stages which are distinguished by maximum earthquake.The first stage is basically in agreement with foreshocks.There are clear differences between the late stage sequence and the foreshocks in manner of frequency attenuation,the rate of strain release and the stationary of focal mechanism.It is believed that these differences are criterion of distinguishing foreshocks from small earthquake swarms.
It is shown that the messages of judging small earthquake swarms or foreshocks can be found by comparing small earthquake swarms with foreshocks.These messages are useful in earthquake prediction.

Abstract:Based on the observation for more than ten years,it is pointed out that the following four aspects are manifested by earth-resistivity ano-malies before an earthquake:(1) The form of the anomaly (rise or drop or undulatory variation of earth-resistivity) is connected with the force conditions acting on the medium around the observation site;(2) Aniso-tropy is evidenced by the differences in the anomalies along different di-rections;(3) The amplitude,duration and areal extent of the anomaly increase with the magnitude of the earthquake;(4) When a strong earth-quake is impending,the temporal and spatial distribution of resistivity anomalies are similar to the distribution of small earthquake activity,and the earth-resistivity does not resume its original values after the strong shock.
The above phenomena have been verified,though in different degrees,by experiments on the variation of resistivity of beds of rock (or earth) under artificial pressure in situ.It is finally suggested that more extensi-ve observation of earth-resistivity and closer study of its anomalous beh-avior will be beneficial to the improvement of its effectiveness as a mea-ns of earthquake prediction.

Abstract:The characteristics of seismic activity in Gansu province and its nei-ghbourhood during the recent relatively quiet period have been studi-ed in this paper.The synchronism of the peak values in the curves of fre-quency and seismicity strength of the small and moderate earthquskes in Gansu region during the period of 1966-1979 with the occurrence of earthquakes of magnitude M_s≥6.5 in Yunnan,Sichuan and Qinghai pro-vinces has been mainly discussed.

Abstract:Since 1955,it has been a normal period of Seismic activities without the earthquake of M_s≥6.0 in Gansu region.This paper discusses the activity characteristics of variant magnitude class earthquakes during this period.The normal background value in seismic activities and ab-normal director of precursor activities of the large earthquakes with magnitude M_s≥6.0 in future are suggested.Finally,the seismic activi-ty trend of the coming years in Gansu region is analysed

Abstract:1970年1月5日云南通海发生了7.7级强烈地震。至今十年中已发表了不少关于通海地震的文章,对地震地质背景、震源过程、烈度分布、形变特征等都作了较深刻明晰的研究。本文拟就现有收集到的资料对通海地震前的地震活动特征予以初步的讨论。

Abstract:A homogeneous dilated sphere in the hemi-infinite elastic space is ta-ken as the mechanical model of the quickly uplifted mantle.With this model the radius and the dilative intensity of the sphere can be com-puted from the value of the vertical displacement on the earth's surfa-ce.The supplementary stress deduced from the uplifted is determined.The computing result showes that the deduced stress on the fault with high inclined angle is tensile,but the shearing stress is also found in the upliftel region of the earth's crust.The amount of these stresses deduced from the quickly uplifted mantle greatly overcomes the stresses deduced from the gravimetric earth-tide,the diviation of the polar axis and the variation of rotational velocity of earth.Consequently,the quickly uplifted mantle has more trigger action than above-menti-oned factors for the occurance of the shallow tectonic earthquake.Ow-ing to the fact that many large earthquakes occur ed recently in China have been affected in the uplifted region of earth's crust or in its ne-ighborhood and these earthquake faults have high inclined angle,their occurance can be explained by the results described in this paper.

Abstract:For a long time it was rarely dealt with the effect of site conditions to earthquake damage in the area,where intensity was more than 9 degree.By detailed studies both in the Railway-North and Eastern Mine Districts of Tangshan city,it was discovered that in the high intensity region the intensity anomaly due to the site conditions was still very obvious.The main factors are as follows:
Ground: Soil(1) The buildings located on limestone,well-cohered san-dstone with thick stratum or on thin eluvial overburden on bed rock were damaged in 2-3 degree of intensity lower than that on other con-structions site;the damage of buildings located on shale or shale with thin strata of sandstone is more serious than that on limestone and sandstone,because the rock is looser,lamellation,stratum and crackle are much developed.(2) The damage on ordinary clayey Soil,clayey sand is heavier than that on bed rock.But the intensity of damage pre-fers to be dependent upon the property of bed rock,the thickness of quaternal overburden and type of constructions rather than property of the very quaternal deposite.The up limit of thickness of the over-burden on limestone,being able to effect the damage is ≥20 m for sim-plstory building and ≥35 m for multistory buildings;While asthe up limit of the thickness of the quaternal overburden on sandstone is ≥20 m for simplstory buildings;on shale-is about 15 m for simplstgry buildings.(3) The grotind soils which may be failed during strong ground motion are as follows:1) unstable soil,2) non-uniform soil,3) saturated olayey soil (puddiy soil) and 4) liquefacted sandy soil.
Local Topography: Local topography obviously effects on the earthquake damage.Such topography includes isolated hill,deep quarry,mountain slope and the top or slope of hills,consisted of strong weathered sha-le.Within the identical intensity region and on the identical,ground soil,the constructions on above-mentioned local topography were sub-jected heavier hazard than that far away from them for its amplifying effect
The hazard of building within or near by the calapsed area of the coal mine also appears heavier due to increased deformation of ground surface during earthquakes.

Abstract:Strengthening the foundation soil with the powerful rammer has been developed for the last 20 years.This method has gradually been emplo-yed in China since the 1970s,and during this period some results of experiment were informed but there is still not enough experience now for strengthening the soaking setting loess and for the restruction of the old urban area in cities.This is just the object for which this pa-per is written.
Two construction sites in Lanzhon were chosen for obstruction on the Vibration effects from the powerful rammer.Observation was carried out along several sections.Among them some sections are across shocking protective ditches with different width and depth.
The results of abservation are as follows:
1.Both displacement and acceleration on soaking settling loess from the powerful rammer increase with the subseqttence of driving rammer and rapidly reduce with the distance.and the attenuation of displace-ment in radial direction is faster than that of acceleration.The chara-cteristics of attenuation of displacement and acceleration on the ident-ical point are different from each other.
2.when the depth of the shocking protective ditch is greater than 2 m and its length is 5 meters more than the dimension of structures,its pretecting effects from shocking are obvious,especially for horizontal vibration in radial direction the effects of the protective are not dep-endent on its width.
3.It is effective to strengthen the soaking settling loess by employing the powerful rammer.The experiment shows that the effective depth of strengthening is 3-5m,whereas the influenced depth may reach 4-9m below the ground surface.

Abstract:The field of the tectonioc stress in Lanzhou-Tianshui region was studied by means of photoelastic simulation.Results show that the points where maximal shear stress concentrates are distribfited along NNE and NWW conjugate shear lines and agree very well with the epicentral locations of some historically strong earthquakes.The orien-tations of the principal stress in the present region tally with the mechanism solutions of earthquake foci.
By loading in different directions and punching on the structure mod-el,it is proved that the accumulatioh,adjustment and movement of en-ergy have close relation to the action manners of forces and are strictly controlled by the field of regional stress.In the particular tec-tonic places distributed along the conjugate shear directions of the re-gional stress field,strong earthquakes,will most likely develop and oc-cur.This will provide some useful data for forecasting strong earthqu-akes.

Abstract:In this paper we have established calculation formulas to estimate errors,σ_φ,σ_λ,σ_T0,σ_h and σ_v,of the approximate solution,starting from error equation using the idea of "error concentration"。These fo-rmulas can be used as the important constituent of the periodic optim-um iteration method。

Abstract:In this paper,we have calculated the accuracy of the determination of earthquake epicenter and origin time in the network of Shanxi and its adjacent provinces by Monte Carlo method.In order to study effects on the accuracy of determination of earthquake epicenter and origin time caused by random errors of arrival time of each station and sta-tion number,respectively,the calculations under the condition of diffe-rent errors and station numbers have been completed.Besides,when a certain station has made an extremely large error,the change of ac-curacy of the network can be calculated.And the isorithm of errors of the determination of location and origin time under each condition can be drawn.

Abstract:Model PZ40 digital earth-resistivity equipment is a new automatic eq-uipment for the measurement of the earth-resistivity.
The present article emphatically elucidates the main techniques for improving accuracy and restraining interfere,and introduces the gen-eral usage of the equipment,its main technical indications,its princi-ples of work and its effects for use,etc.

Abstract:In geophysical problems,two methods commonly used in the interp-retation of geomagnetic and geoelctric field anomalies are numerical modelling techniques and laloratory analogue model methods.Laboratory analogue models are found to be very useful in anatysing problems which do not yield really mathematical solution,and have been extensi-vely used in studying complicated geophysical problems.
The present work reviews the development of analogue model method in the world,especialty in Canada;describes various kinds of source field models,such as plane wave model,line current model,and mag-netic dipole model;and shows the applications to studying the coast effects,island-continent ocean channels,electromagnetic effects inducec by ocean waves,aond anisotropic conductors.The results of comparison of analogue model measurements and numerical calculations indicate very good agreement,arid confirm the validity of the analogue method for studying complex two-and three-dimensional induction problems.such research work goes a long way in understanding the behaviour of natural electromagnetic field,carrying out geophysical prospecting,and investigating the electrical structures of the Earth's crust and mantle.

Abstract:负二项式分布远比简单波松分布更符合于地震次数的观测分布。所以用负二项式分布代替简单波松分布以建立极值模式,将使统计效果得到改善。

Abstract:我国自一九六六年邢台地震后,在全国很多地区开展了地磁预报地震的研究工作,创造和积累了不少经验。与此同时,地磁台站得到相应发展,在这些台站中,有相当一部分是相对量记录,无绝对观测仪。因此,在震磁关系研究分析中,普遍采用的是北京时整点值相对量资料。