1991, 13(2):1-7.
Abstract:Using Fourier transformation, the 3-D boundary value problem of electric field of point source on 2-D geoelectric section is converted into 2-D boundary value problem. Then we discussed the application of boundary element method for calculating apparent resistivity on layered medium which contains 2-D column body. The integral calculation of horizontal boundary is avoided because of the selection of basic solution. So, the number of all needed boundary cut joints are much less. Particularly, it need not calculate the partial derivative any more, unknown quantities are decreased very much, so that it calculates 2-D boundary value problem conveniently. And using Fourier inverse transformation, we can obtain electric potential in 3-D space. The mathod proposed in this paper requires less memory, less ariginal data needed for computer input, and has higher calculating accuracy.
1991, 13(2):8-21.
Abstract:On the basis of dispersion relations for the magnetotelluric (MT) field,the physical meanings of 1-D joint inversion of MT data are expounded.The necessity and applied prospects of the joint inversion using a pair of MT response functions,especially the apparent resistivities of the impedance's real and imaginary parts,which are relative with the dispersion relations,are inferred.The effects of the single parameter's and joint inversions for MT impedance are tested.It is shown that in the aspects of increasing the velocity of the inverse iteration,limiting the non-uniqueness of the inverse solution and assuring the stable convergence of the inverse iteratinn,the joint inversions are more advahtageous than the single-parameter's inversions,in the most cases the joint inversion using the apparent resistivities of impedance's real and imaginary parts is more advantageous than the joint inversion using the normal apparent resistivity and impedance's phase,which is usually used now.The test for practical MT data shows that the use of the various average impedances and the synthetic interpretation of them will help to obtain more reliable results.
1991, 13(2):22-28.
Abstract:After much discussion of origin mechanism of tectonic earthquakes a mathematical model is advanced in this paper. With this model, not only the stick-slip behavior in rock's tests can be simulated, but the occurrence of tectonic earthquake can be analyzed qualitatively and quantitatively as well. In addition, by the numerical simulation of Tangshan earthquake sequence, a group of mechanical parameters and some qualitative understanding for the deeply buried rocks in seismic area of the Tangshan earthquake are obtained.
1991, 13(2):29-38.
Abstract:First, to the eight minor regions in and near Gansu Province, the background b-values are computed and the least magnitude lower-limits for the calculation of the b-values are determined. Then, the two calculation methods are compared. Finally, the relation of the b-value changes to the moderate earthquakes is discussed. The research shows that there are some abnormal changes of b value in and near epicentral regions before about half of the moderate earthquakes that are studied in this paper. The change of b value can be regarded as a reference factor for earthquake prediction.
Wang Anbin , Wan Dengbao , Yang Guojun , Huang Zhenyi
1991, 13(2):39-44.
Abstract:Based on the analysis of the anomalous characteristics of groundwater outflow before Lancang-Gengma strong earthquakes in Yunnan, the mechanical mechanism of the anomalies is discussed in this paper. We have obtained the following conclusions:the groundwater outflow has extremely sensitive reflection ability for tectonic stress and earthquake activities in a region. The anomalies of groundwater outflow mostly occurred during the short-term and impending earthquakes, and the concentricity of anomalous duration, the generality and heterogeneity of regional distribution, the complexity and diversity of anomalous variations are appeared as well. With the change of epicentral distance the anomalous variational quantity showed certain regularity.
Wang Shuding , Wang Hua , Xiao Wencheng
1991, 13(2):45-50.
Abstract:In this study, the background values of seismic hydrogeochemistry in west Shandong Province are obtained. The regional hydrogeological condition, wall-rock components, structural condition and tectonic activity are major factors influencing components of water and gases. The variations of hydrochemistry components in wells and springs which are located in the active structural zones are sensitive to earthquakes, but sensitive factor reflecting earthquake for each well and spring is different.
Wang Xiuqiong , Yao Zhengsheng , Zhang Cheng
1991, 13(2):51-55.
Abstract:Using the method of seismic tomographic image of joint inversion and rapid two-point ray-tracing method to process the arrival-time data of natural earthquakes recorded by regional Hexi seismic network, we obtained the 3-D velocity anomaly distribution of the upper and middle crust in Hexi area. According to the inversion results, the earthquake risk in Hexi area is discussed.
1991, 13(2):56-62.
Abstract:In this paper,the clustering phenomenon of earthquakes in the region surrounding Ordos Block and Shaanxi Province has been researched using grey system theory.The grey forecasting models GM(1,1) for the clustering time-section in the two areas have been built respectively.The forecasting results show that the next clustering time-section of Ms ≥ 5.5 event is from 1987 to 1994 for the region surrounding Ordos Block and that of Ms ≥ 4.0 event is from 1990 to 1995 for Shaanxi Province.The testing results also show the models have higher precision.
Tang Jiu'an , Yang Jiawen , Zhou Zhiyu , Chang Qianjun , Qiang Keyu , Bai Yaping , Peng Weirong , Cao Wenxiang
1991, 13(2):63-67.
Abstract:The harmonic analysis results of the data of type-FSQ water-tube tiltmeter observed at Lanzhou deformation station from 1987 to 1989 are introduced. The repeatability of the tide factors and the monitoring ability to the non-tidal variation are discussed. The influence of meteological factors on diurnal wave is analysed. Finally, a comparison between the observed tide factors and the theoretical values of G-B earth model is made.
1991, 13(2):68-75.
Abstract:From statistics it is discovered that the earthquake repetition rate in terms of intensity and the distance in China continent has the constant ratio between the intervals and follows the number of 0.618. It shows the repetition process of time of earthquakes with different magnitudes doesn't keep the same but are correlative. This indicates the generality of all natural things.
1991, 13(2):76-82.
Abstract:In this paper, it is found that power spectrum of earth tremor corresponds to acceleration peak value and response spectrum of ground motion using comparison analyses between the practical data on the seismic microzoning of Xining City, where the basic intensity is 7 degrees, and profiles of borehole is well. Therefore, in this context, the earth tremor can indicate the engineering-geology properties of Quaternary overburden layer under a certain site condition more directly, and the method of evaluating site by earth tremor may be regarded as a simple, convenient, and economic one of evaluating engineering site, used with other methods together.
1991, 13(2):83-86.
Abstract:1986年11月15日在我国台湾省花莲海域发生了一次7.6级强烈地震及其随后的一系列余震。这是台湾经历了8年(1979-1986年)地震相对平静期后,发生的一次强震。除台湾省台北、花莲、宜兰等地遭受严重破坏和人员伤亡外,福建、广东和浙江三省的沿海地区也受到波及,有感半径达600-700公里。这次地震前闽赣水位观测网的深井水位异常特征明显。本文对此进行了讨论。
1991, 13(2):87-89.
Abstract:绥化台位于黑龙江省绥化市西南郊区,台址位置为东经126°57'50″,北纬46°37'30″。该台所处构造部位属于新华夏系第二沉降带,测区内分布有走向约N18°E的绥化-逊克主干断裂带,並有NE向、NW向断裂与之斜交或斜切。
1991, 13(2):90-92.
Abstract:山西地堑由于其特殊的地理位置及构造运动的特点,成为我国一条重要的地震活动带,因而,引起了国内外地质学家的注目。本文基于此点,利用最新的重力测量资料,反演计算了山西地区莫霍面形态特征,试图揭示山西地区深部构造与地震震中分布的关系。
1991, 13(2):93-95.
Abstract:北纬35度线是地球赤道到北极这一纬度区间的黄金分割线。在中国,大地水准测量发现该线以南上升,以北下降,这与地球自转和日月引潮力所形成的地球升降交界线相一致。在中国35度线上不同段上的强震活动有准同步性,且有准60年或其倍数年的间歇期。如上一活动期以1936-1937年为准,预计在1996-1997年和其前后几年该线上应有若干次强震活动。再者该线与别的斜向构造或地震带相交部位一般易发生7.5-8.5级大震。故预报在该线与喀喇昆仑构造交汇部位今后几年内可能会发生7-8级地震,在北西向断裂系与该线交汇的黄河源和长江源地区今后几年可能会发生7级左右地震。
Sopyright:China Earthquake Engineering Journal