Abstract:In this paper,by using the electric potential distribution which is originated from the artificial point current sources in the earth model of two horizontal layers as basic solution,we deduced the boundary integral equations about electric potential with an inhomogeneous conductivity object in the earth.Then we got the electric potential distribution on the ground by solving the integral equations with boundary element method,further,we got the calculating results of apparent resistivity.
That the integration is only done in the boundary planes and the direction of observational line is arbitrary are the specific advantages. Using united-section methed,we calculated the apparent resistivi-ty with an inhomogeneous spherical object in the model of homogeneous half space,the results con-formed to the analytical solutions got by other researchers. Using gradient-section method,we calcu-lated the apparent resistivity with a rectangular inhomogeneous object in the lower layer,the angle be-tween the direction of observational line and the trend of rectangular objct is 45°,the results con-formed to the experimental and theoretic analytical solutions got by other researchers.
Finally,we discussed the applications of this method in the field of the precursors of ground resis-tivity and the electric prospecting.

Abstract:In this paper,earthquake response analysis of some typical fault areas using the two-dimensional finite element method was carried out,in which the effects of other factors on macroseismic damages were removed,taking into account comparatively all-round factors influencing the peak ground accel-eration and acceleration response spectrum,such as the scale of rupture zone of faults and soil physi-cal-mechanic properties within the zone,attitude of fault surface,fault displacement,thickness of overburden layers,undulation of bedrock,dynamic property of seismic input to a microzoning area, etc.. Combining relevant macroseismic damage data and analysing these problems tentatively from different angles,this paper concludes that the actual earthquake damage effects of non-causative faults,to a great extent,present stochastic character and its degree depends upon the type of combi-nation of fault factors and various external conditions.

Abstract:In this paper,the space-time structure of shallow-layer ground temperature anomaly and the hor-izontal structure of precipitation anomaly before,during and after the origin month of the Dongchuan earthquake in l966 are analysed. The analysis indicated that the positive anomaly of ground tempera-ture almost steadily lasted several months before the seism,and then arose remarkably and reached to the maxium during the origin month,and it generally fell after the seism;the epicenter located in a negative temperature anomaly area before the seism,then when the seism coming the negative anoma-ly area evaluated promptly to a positive one and its strength and area continuously increased,and got to the maximum during seismic month,they decreased after the earthquake;the thermal anomaly transfered from the deep layer to the surface;the epicentral area is dry and rainy,respectively,before and after the seism. Furthermore,the condition and the possible mechanism by which the thermal in-formation at focus transfered to the surface are also discussed. It shows that,at least for a shallow focus earthquake,the convective heat transformation must is a possible way of heat transformation.

Abstract:In this paper,the propagations and rupture characteristics of some typical combined cracks in the physics of earthquake focus,under biaxial compression, are studied by means of dynamic photoelastic-ity. The crack paths and propagation stability are analysed,comparing with the uniaxial compression. In the meanwhile,the effect of opposite crack face friction on crack propagation is studied.Some con-clusions,such as crack stable propagation in a compression-shear stress field,are obtained.

Abstract:Gravity repeated measurement had carried on Northern Loop with station distances l50-200km of striding across the different tectonic units using LCR-G gravimeter. Shallow interference factors were analyzed from different angles,and the gravity change relative with earthquake was discussed.This is a comparative practical research approach on earthquake precursor using gravity survey. For example,the data of Datong earthquake,the gravity change was exceeded each standard error before and after moderately strong earthquake.For studying the process of earthquake preparation,the ref-erence data were offered from the features of gravity change.

Abstract:Based on the statistical correlation analysis,we find that the monthly mean geopotential height at 500 hPa which can be presented the circulation features over Northern Hemisphere is certain related to maximum earthquakes for Jan.-June and July-Dec. in Yunnan Province. From the stepwise regres-sion forecasting analysis mentioned above,it chooses main circulation factors influencing the earth-quakes,and sets up some regression forecasting equations for the maximum magnitude.

Abstract:In this paper,we introduced the anomalies of fault-gases Rn,Hg and H₂ at Jiayuguan station be-fore the south Jiayuguan M5.4 earthquake. By comparing with the seismicity and leveling survey across the faults,it is shown that the anomalies are indeed the precursor of this earthquake. By study-ing the features of geological structures at the observation point,it is considered that Jiayuguan fault-gases correspond well to many earthquake because the point is situated in the position where the struc-tures are sensitive to multi-way force sources.

Abstract:The common Vondrak smoothing filtering method,used in astronomy data handling,was adopt-ed here to deal with the two groups of fixed point horizontal and vertical crust deformation data by means of high-pass,low-pass and band-pass digital filterings,respectively.The results showed that after handling the data,the abnormal informations of crustal deformation for different periods prior to the shocks were obviously and the effects of background noise and observing error were reduced as well.It also indicated that the method is of a better capability for recognized the abnormal of pre-earthquake deformation.

Abstract:In the light of the theory of material differentiation,this paper describes the transformation of crustal types from one into the other and discusses the fundamental characteristics of crustal evolution in southeast China. On this basis,southeast China is divided into different crustal divisions,and the relations between tectonic feature and seismology are discussed.
The results show that material differentiation has been taking place only weakly in major deep fracture zong of southeast China inland,resulting in a low intensity of fracture activity and in the qui-escency in seismicity;whereas in the eastern part being close to the subduction zone of Philippine Plate,material differentiation is strong,fracture activity and seismicity are significantly strengthening.

Abstract:In this paper, based on the geophysical field,the magnetic sounding formula and more general one of gravity sounding are submitted by way of the derivation of mathematics and physics in geo-physical circle. In order to receive more exact solution,the iterative inversion in space domain is put forward with optimization theory. On the other hand,in light of geophysical model,we improve the Gauss optimization theory so that the calculating method is simple and the computing soeed is very quick.With an amount of test results of various models listed in this paper,the effectivity and reliabili-ty of the magnetic sounding formula are also discussed.It is satisfaction to process the practical data using the method proposed in this paper,and its practical value has been testified.

Abstract:Based on“The Seismic Risk Analysis of Jiayuguan City”,this paper anticipates the seismic disas-ter of Dacaotan earth dam. We calculate and analyse the dam's nonlinear dynamic characteristics using dynamic nonlinear finite element method,and give the possible pull-open regions on the dam's surface and the possible plastic failure regions in the dam under l0% and 2% of exceedance probability during a period of 50 years,andgive the acceleration time history and shear stress time history of several rep-resentative points. We also calculate and analyse the whole stability of the dam. Under the two ex-ceedance probabilities,this paper gives the whole safe reliability during a period of 50 years.

Abstract:Based on the historical and present data,this paper deals with some characteristics of earthquakes with magnitudes 5 or so in Shaanxi, such as seismic time interval,rhyme,rhythm,correlative earth-quakes and space-time distribution,which will provide the basis for seismic situation judgement in Shaanxi.

Abstract:1990年1月-1992年12月,作者在滇西地震预报实验场和甘肃河西地震重点监视区分别选择了一些观测井孔、泉点,观测水中汞含量的变化,探索其与地震活动的相关性。

Abstract:武山温泉位于甘肃省武山县洛门镇南15km处。在地貌上温泉周围地区属于中高山区,海拔在1700m至2400m,地形较为陡峻,沟谷纵横交错。在构造单元上该地区属于巴颜喀拉地槽西秦岭褶皱系,地处西秦岭北缘大断裂南侧。

Abstract:韩城地区北山山地石灰岩中的破裂现象已引起国内外地震地质工作者的高度重视,并做过多次调查,在一些文献中也有介绍^[1],并有专门论文发表。关于其成因,有人认为是古地震遗迹^[2],有人则否认这种看法。

Abstract:两水应力站位于武都县西北两水村(海拔1100m),地理位置为北纬33°25'40",东经104°48'20",在构造上,属于武都弧形构造带前弧西翼。

Abstract:Based on the data of the landslides caused by several historical strong shocks since l970 in southwestern China,this paper concluded the geological and geomor-phological conditions of earthquake-induced landslide In this region,and discussed the rela-tionship of landslide distribution and earthquakes. Finally,the main points on evaluating the hazards resulting from earthquake-induced landslide were also put forward in this paper.