Abstract:In this paper, a new non-uniform fault model with crooked fault surface is proposed. The crooked fault surface has been simplified as zigzag shape. When the slip and the travel velocity of dislocation on each saw tooth are uniforrm, we have found the analytic solution in enclosed form for the simplified problem. The amplitude spectra of body wave radiation have been calculated for different numbers of tooth, inclined angles of tooth and position angles of the field. The studied results show:1) the crooked fault can make unusual peak appear in spectral curve, the position of the peak is dependent on the tooth number, and moves towards the point of high frequency as the number increasing; 2) the change of the inclined angle can cause the change of spectral envelope line near the unusual peak; 3) the shape of amplitude spectrum is different for the observing point with different position angles. Comparing observed with theoretic spectra carefully, ones perhaps understand the non-planar feature of fault surface.

Abstract:In this paper, we have researched the space-time distribution characteristics of small earthquakes sequence before and after large earthquakes from information amount, and defined lack information amount I_Q value to reflect the distribution which hides the anomalous information of large earthquake in future. As some examples of the Haicheng, Tangshan, Helingeer and Manasi earthquakes, we have analysed the dynamic variations of I_Q values before and after these strong earthquakes.The results show that the I_Q value had appeared notable low value phenomena before the strong earthquakes took place. We believed that I_Q value can quantitatively describe the information of various phenomena patterns of the seismic space-time distribution before large earthquake. It is a good way to monitor and forecast large earthquake.

Abstract:Using the short-period conversion function and extracting local anomaly from the geomagnetic field, we have re-studied the variation of the geomagnetic field before and after the Heze 5.9 earthquake. It is concluded that before Heze 5.9 earthquake, there exists anomalous variation in short-period component of the geomagnetic field and local anomaly of the fundamental geomagnetic field in Heze and its vicinity. These anomalies synchronize and have similar shape with the b-value, activity of small earthquakes and some other precursory anomalies.

Abstract:This paper describes the normal and anomalous features of electrotelluric field before some earthquakes in Hexi area of Gansu Province, based on the data observed at five stations in Hexi area, It points out that study on the anomalies of electrotelluric field is significant for short-term and imminent prediction of earthquake.

Abstract:The precursory characteristics of ground strain before the Liyang earthquake Ms 6.0 on July 9,1979, Sheyang earthquake Ms 5.1 on Feb.17, 1987, Changshu-Taicang earthquake Ms 5.1 on Feb.10, 1990 in Jiangsu Province, China are analysed in this paper. And some questions about the imminent earthquake prediction using the impending earthquake precursor of ground strain are also discussed.

Abstract:大震与大洪、大旱的相关性有同域相关和异域相关。1991年4月24-27日在兰州举行 "全国天灾预报研究会",我们指出,蒙、新、甘交接地区发生7级以上大震后,黄河流域往往有大洪或大旱。这是异域相关。1991年从太阳活动来说,符合黄河大洪指标,但相关区的大震指标不具备,故预报1991年不致发生太大洪水。

Abstract:Three variation patterns of U_SH-U_SV of the Nov. 6,1988, Lancang-Gengma earthquakes(M=7.6, 7.2)have been obtained through calculating and analysing the S-wave polarization angles before and after the earthquakes. The variation characteristics possess precursory meaning. Study on the distribution of maximum amplitude ratio of P-and Swaves and spatial distribution of S-wave polarization angles before and after the earthquakes shows the line of 22°57'north latitude may be the medium boundary between Lancang and Gengma areas.

Abstract:Loess seismic landslides are usually the most outstanding and serious disasters type in disaster area of earthquakes. To seek for a method of predicting the earthquake disasters, the authors made a study of seismic stability analysis on the typical Huihui Chuan loess seismic landslide in Xiji county with 10 degree intensity of the great Haiyuan earthquake in 1920. In order to conform the analysis result to reality, the parameters gained from strength tests on dynamic triaxial apparatus by an irregular wave of random seismic loading was used. In the stability analysis, a method of soluting critical seismic coefficient was adopted. The result of invering the landslide is coincident with reality. For clarifying the forming rules and the stability analysis of loess seismic landslides, this paper provides a more accur ate method which is more conformable to reality. This paper brings it forth new ideas to apply strength parameters under random vibration and the method of stability analysis.

Abstract:In this paper, by use of an APPLE-Ⅱ microcomputer controling a dynamic triaxial apparatus made at home, the dynamic strength tests are directly performed on a loess by employing random time histories of seismic load. The method of determining the dynamic strength of loess under the seismic loading from relation curves of dynamic stress and residual strain was presented. And then, the Huihuichuan loess landslide induced by the 1920 Haiyuan earthquake (Ms=8.5) is inverted, and the inverted result coincides with the real seismic damase.

Abstract:In this paper,the Nakai's fitting method is improved and it is applied to the calculation of tidal and barometric coefficients of the well level.The advantage of this method is that the lag time of the response of the well level to the tide and barometric pressure can be calculated.The well Lu-06 is instanced.We have calculated by this method that the tidal coefficient is 16.9mm/10^-8,the barometric coefficient is 5.58mm/hPa,their lag time respectively is 18.8 and 22.4 minutes for the well level.The corrected standard deviation decreases from 8.5mm to 6.1mm.

Abstract:This paper proposes the method of direct forecasting epicenter with multipoint aimed at predicting the probable areas of coming strong earthquakes. The procedures of this method are:selecting four reference-points out of any seismic areas; writing down geocentric angles relative to the reference-points of each epicenter on the coordinate plane; finding out the curve of epicentral space movement law. Different curves show different movement states, each state migration of epicenters accords with Markov process. Thus, the earthquake occurring probability in future can be predicted for any seismic area. Finally, Using this method, the future seismic situation for some seismic areas in North China is predicted.

Abstract:This paper deals with the effect of the structure of crustal quality factor Q on the measurement of Q value.Most of reported results show that there is some positive correlation between Q value and ray path of seismic waves.Therefore,for explaining the spatial distribution of observed Q values,not only the effect of seismic frequencies,but also analysing and correcting the effect of ray path on epicentral distance must be considered.Finally,according to current crustal velocity model of Chinese Continent,by calculating the seismic ray path in horizontal layered medium,the authors obtained the functional relation between the epicentral distance and the maximum depth of ray path,and give the structures of crustal Q in North China and partial areas of Southwest China.

Abstract:Based on the covering dimension method for measuring the San Andreas fault system applied by P.G.Okubo,the fractal behavior of Haiyuan Quaternary active fault system has been investigated.The fractal dimensions for the entire fault system and its two of the four segments,Jingtai and Haiyuan,are obtained,i.e.D_QB=1.137,D_OJ=1.109 and D_OH=1.182.The fractal dimensions for the other two segments,Shaojiashui and Lijunpu,aren't obtained,so the SL segments are self-affine or nonlinear fractals rather than self-similar ones.It.may be seen that the real seismic faults are more complicated than ideal ones,should be multifractals or self-affine.Basides.the correlation between fault geometry and seismicity,mechanical circumstance around the fault system has been emphatically discussed.It further proves that the geometry complexity of self-similar faults is close to seismic activity;shear faults have lower fractal dimensions (1.1-1.3);but the fault systems formed in tensional circumstance have higher fractal dimensions (1.5-1.6).Finally,this paper discussed the effect of fault trace map,etc.on the measuring accuracy of fractal analysis.

Abstract:桌子山断裂是南北地震带北段地区内的一条长期活动的大断裂带。1989年,在为石咀山电厂扩建工程区作地震危险性分析与断裂活动性评价工作中,笔者对桌子山断裂带进行了较系统的实地考察,并取得了大量断层新活动方面的资料。

Abstract:兰州地区地质构造复杂,且大部地区为黄土覆盖,因此虽然以往做了不少地震地质工作,但对该区的地震构造条件的认识尚有进一步研究的必要。本文试图根据卫星影象的解译结果,分析兰州及其邻近地区活动断裂的展布特征及其与地震的关系,为该区地震危险性的研究及地震预报提供资料。

Abstract:研究区(图1)位于东秦岭以南、江汉平原以西,是丹江水库及葛州坝所在区域。考虑到研究区包含了不同的构造单元,将该区划分为两个小区域进行处理。以青峰断裂为界(约北纬32°),鄂西南以黄陵背斜为主体,范围为北纬30°-32°,东经108°-112°;鄂西北以武当地块为主体,范围为北纬32°-34°,东经108°-112°。所用资料选自《湖北省台网地震目录》。

Abstract:自1970年以来,云南已先后发生了4次Ms ≥ 7级强烈地震(1970年1月5日通海-峨山7.7级、1974年5月11日永善-大关7.1级、1976年5月29日龙陵-潞西7.4级、1988年11月6日澜沧-耿马7.6级),说明云南地区的地壳可能经常处于非稳态,易因内、外涨落加剧而产生状态突变。为此,本文专门做了系统的资料分析,初步勾画出了云南强震前一再重复出现的如下基本物理图象:1.强震前5年,其周围二百余公里范围内5-6级地震明显活化;2.震前1-3年,震中区降水剧变,出现罕见的旱涝振荡;3.进而,M ≥ 3.7级地震频次呈非线性增长,不久,气压出现短临性巨涨落;4.强震总在一定的天文时刻爆发。研究上述的地壳内、外巨涨落过程,不仅有助于云南强震的实际预报,亦有助于孕震动力模型的研究。