1995, 17(3):1-9.
Abstract:Based on the universal law of precursory fluctuation intensification before strong earthquakes,this paper takes the 1990 Gonghe strong earthquake as an example to study multi-hi-erarchy of the precursory fluctuation intensification of the small earthquake frequency,the modulation ratio of small earthquakes,radon in groundwater and hydraulic discharge in spring before the earthquake.According to the phenomenon authors considered that the multi-hierar-chy of the precursory fluctuation intensification is an important path for prediction by following the tracks of a strong earthquake.
Liu Xqiang , LiQinghe , Li Hong
1995, 17(3):10-16.
Abstract:Based on the discussion about the effects of free-surface on the incident shear wave,this paper first puts forward a method used to treat the S-wave splitting data outside the critical window.After correcting the amplitude and phase of vertical and radial components,authors analysed the data by using the greatest characteristic values and waveform discrimination operator method,and also analysed explosion data in Tianshui area of Gansu.It may be seen the data show the seismic phase of S wave and S wave fission.
1995, 17(3):17-25.
Abstract:In this paper,by using some view points of non-linear dynamics,for example,sensitivity to original condition,fractal dimension,bifurcation,chaos prediction size of earthquake process,and so on,we discussed the modulation triggering,common dimension time and area and inlay modulating of small earthquakes.Author also analyzes some anomaly phenomena of the Gonghe earthquake in Qinghai province in 1990.The analysis has certain reference value to understanding precursory complexity of earthquake.
1995, 17(3):26-32.
Abstract:Earth-resistivity (ρs) changes of Wuwei geoelectric station before and after earthquakes of M 6.2 in Jingtai county,M 6.4 in Menyuan,M4.7 in West of Tianzhu,M5.6 in Danmaand M4.7 in Yabulai (Δ ≤ 150 km),as well as M7.0 in Gonghe (Δ=270 km) in this paper.Conclusions are follows:(1) Short-impending ρs anomalies up to 10-1-10-2 magnitude were recorded in EW observation direction at the station before the former 4 earthquakes,short-term ρs anomalies up to 10-2 magnitude which were decreased were recorded before the Gonghe and Yabula earthquakes.(2) The short-impending ρs anomalies in the direction were probably caused by the move of ground water along second faults,rifts or fissures in the late period of seismogenic process,since earth medium within the range of exploration in the direction was fragmentary.Finaly,author thinks,the reflecting earthquake ability of short-impending ρs change in EW direction of the station is higher for moderate and strong earthquakes occurred in certain region around the station.
1995, 17(3):33-42.
Abstract:In this paper,the authors made use of three methods,including slip-average with variable amplitude,slip-residual and massive abrupt rate,to carry out systematically comprehensive processing for those data after groundwater chemistry network established in western Yunnan area.The correlation analysis between above results and more than 10M > 5.0 earthquakes in the neighboring areas shows that this network has very good reflecting earthquake ability,the efficiency of station-point is 0.67 and the efficiency of station-item is 0.53.The general response earthquake range is less than 100 km.Before earthquakes occurring within the network,all station-items have appeared background anomalies,the earthquake will take place after all pionts go into anomaly turning stage.The length of the anomaly duration and the magnitude of the anomaly amplitude are positive correlation with intensity and epicentre distance of the future earthquake.The short information is to be massive abrupt,about 40-50 days after massive abrupt rate reached peak and turned,and then the earthquake will occur.
Finally,we also discussed the near source field earthquake information observed by the groundwater chemistry network in western Yunnan area.
Zhang Wenmian , Ni Mingkang , Tao Shfen , Zhang Peishan , Yao Jun
1995, 17(3):43-47.
Abstract:In terms of analysis on the continuous change curves of radon in groundwater at more than twenty measuring points along the north China and North-South tectonic belt,it is found that the tendenciously high value anomaly and abrupt anomaly were common during the high seismicity period from 1966 to 1976.But during the low seismicity period from 1977 to 1985,the groundwater radon value is stable except the short-term tendency anomaly or abrupt anomaly at few points in local area,It is considered that the hydrochemical anomaly field under the action of the regional stress field during high seismicity period is an important indication for the prediction of one-by-one strong events.
He Genqiao , Chang Qiujun , Song Yulan , Cheng Tiande , Jiang Yonglin
1995, 17(3):48-53.
Abstract:In this paper,authors studied the relationship between seismicity anomalous changes of fault product gases at 4 measuring points along the northeastern margin of Qinghai-Tibet plate.The anomalies of fault product gas components appeared at these measuring points from 1992 to 1993,for example,sudden change and rising of the observed values.The anomalies of various components or/and at various measuring points have obvious synchronism.Authors mainly introduce the anomalies of fault gases observed at many measuring points before the Tuolai M 6.0 earthquake occurring on Oct.26,1993.At last,the field effect of fault product gases is discussed preliminarily.
Guo Daqing , Yang Liming , Shi Telin
1995, 17(3):54-59.
Abstract:On the basis of the systematic study for the mathematical time sequence model,the principle,algorithm,limitation and application in seismology have been researched to transform the discrete models into continuous dynamic differential equation,The equation has been achieved by the observed data,the physical means and the dynamic process of the models have been discussed and the depth of the study for the models has been widened.
1995, 17(3):60-65.
Abstract:Some parameters related to energy of seismic waves E are applied extensively to earth-quake prediction as criteria of seismicity.In general,temporal variation of total areas of seismic.faults ΣS is used for earthquake prediction.In this paper,well use the parameter ΣE2/3 relat-ed to Σ S to plot the curve of ΣE2/3-t and analyse its temporal variation before a large earth-quake.Analysing the curves of ΣE2/3-t before MS ≥ 7.0 earthquakes since 1900,we obtain that the seismicities in past years in a region are known by the E2/3(t) curve of historical earth-quakes in the area,and from this the whole state of seismicity in the region from a few years to a few decades in future is estimated;the possible magnitude of recent seismicity in the regionmay be extrapolated and assessed from the curves.Also the basic shapes of E2/3(t) curves are classified roughly.In this paper,the catastrophe condition and time of the E2/3(t) curve of historical earthquake series in a region are determined from view of catastrophe theory,and the mathematical and physical methods for earthquake prediction are found.
Zhang Zhaodong , Zheng Jinhan , Zhang Guangcheng
1995, 17(3):66-71.
Abstract:In this paper on the basis of the theoretical solutions of the earth tide effect,barometric effect and Oceantide load effect as the boundary conditions of permeation between a well and aquifer,the internal relations of the response of the well aquifer system to three kinds of tidal signals that have different mechanisms,i.e.the response functions of the well aquifer system to tide,have been developed,which involve the amplitude response function and phase lag function of the well aquifer system.The relationship between these two functions and the parameters of the well aquifer been discussed and compared with those under no drainage.
1995, 17(3):72-74.
Abstract:On the basis of anisotropy of mechanical property of rock mass and based on the orthogonal anisotropy elastic theory of rock mass,this treatise has advanced the principle measuring magnitudes and directions of two horizontal principal stresses by hydraulic fracturing method and the method measuring and calculating elastic parameters of rock mass relating to the stress measurement in rock mass.
Liu xu , wang Jianrong , Zhang Senan
1995, 17(3):75-79.
Abstract:In this paper,the elastic wave velocity in saturated soil was discussed in detail.A method is suggested which is used to calculate the elastic wave velocities of frame in saturated soil by using the velocities measured in site,The method can solve some problems on the application of elastic wave velocity in engineering geology.
Li Buyun , Yang Bin , Liu Hongchun , Li Qiang , zhang Xianghong
1995, 17(3):80-87.
Abstract:This paper considers comprehensively concerned data of geology and geophysics within 250 km around the Daba power plant and establishes a 3-D finite element model.The struc-tural stress field in the region is simulated by the model and then the seismic hazard there is analyzed.Danger coefficient and quantitative and qualitative differentiation signs of the potential source region are advanced according to differentiation of seismic safty.It is considered that the structural stability is better near the Daba power plant.
ZhangSuping , Zheng Weiping , Guo Xinduo , LiXiaofeng
1995, 17(3):88-89,95.
Abstract:选取1990年至1994年3月陕西、甘肃、宁夏、青海、四川和西藏自治区发生的5级以上的地震,1990年到1994年2月在上述范围内地磁台站记录的K ≥ 6的磁暴。
Meng Fanqi , Pan Yuzhen , zhang Baihan
1995, 17(3):90-92.
Abstract:作者在台站的长期观测实践中发现,若同一次地震的两种震级差δ出现较大的变化时,其变化结束后该次地震附近地区就有较强地震发生。强震前两种震级差值可超出正常值的一倍至数倍。
1995, 17(3):93-95.
Abstract:地震三要素的预报是一个难题,关于时间的预报更难。近几年来推出的实用化攻关及多种研究成果,使预报规范化了,但预报的准确率仍然很低,这就需要科技工作者进行多种学科和多种方法的研究和探索。
1995, 17(3):96-104.
Abstract:Based on Biot's basic motion equations for the fluid saturated porous elastic medium and by using the method of complex function,the displacement field due to moving source with uniform velocity U in an infinite porous elastic saturated space is studied in present paper,Two types of sources are considered:a.An oblioue concentrated pulse force moving along the horizontal axis of the infinite space,b.The moving couples of forces.There are four cases for the moving velocity of force source:a.The velocity U is less than all three types of body wave velocities of the fluid saturated porous elastic medium,the subsonic case.b.The velocity U is less than the first dilatational wave velocity and the rotational wave velocity of the medium,but greater than the second dilatetional wave velocity,the weak transonic case.c.The velocity U is less than the first dilatational wave velocity,but greater than the velocities of the second dilatational and the rotational waves,the strong transonic case.d.The velocity U is greater than all three types of body wave velocities,the supersonic case.The results show that in the transonic and supersonic cases,the solutions represent the character of plane chock waves attached to the load and associated with a jump in the displacement.
Sopyright:China Earthquake Engineering Journal