1988, 10(2):1-7.
Abstract:The additional stress which is caused either by air pressure and rain fall (The phenomena are defined as air pressure effect and rain effect respectively), or by rise and fall of surface water (such as river, lake etc.) can disturb water level of pressure well. In this paper, the solution of elastic half-space is used to analyse the pressure effect and rain effect. The pressure coefficient by J. Bear is modified and meanwhile the rain coefficient is proposed. Through calculation, we find that air pressure coefficient and rain coefficient are related not only to the behavior of aquifer, but also to the range of pressure variation, area of raining and the depth of pressure aquifer. Some facts of observation have been proposed that the sum of the two coefficients equals unity which is also proved in this paper. Taking Su-07 well as an example, we analyse the disturbance caused by rise and fall of the surface water, and the results of calculation is nearly keeping with the results which are got from the calculation of regression analysis.
1988, 10(2):8-21.
Abstract:This paper deals with the resistivity changes inside a three layer media and corresponding apparent resistivity changes observed in different "epicentral distance" on the surface of the media, which are caused by the additional stress-strain field due to an expanding sphare in the media as a modelling earthquake source.
The results show that for a certain source, the stress field within the detective scale of a given geoelectrical observational system in a given "epicentral distance" varies very much with the layers which have different values of elastic modulus, and that the strain field within the same scale does not vary so much as stress. Thus the true resistivity changes in different layers of the three layer model have been calculated in terms of the "resistivity-strain sensitivity" based on some laboratory experiments, and then the apparent resistivity changes associated with the electrical structure of the same model calculated also, so that we could know something about the relations between the apparent resistivity changes and the strain fields for the earthquake source (expanding sphare). The relations reveal the synthetic influences of both mechanical structure and electrical structure on apparent resistivity changes. For the geoelectrical method as one of the means in earthquake prediction, on one hand, we have to seek the observational site which is of high sensitivity of resistivity-strain for the media, on the other hand, it is necessary that the site has a good response of apparent resistivity change to the true resistivity change inside the media which is of high sensitivity of resistivity-strain.
Gui Xietai , Dai Jingan , Guan Huaping
1988, 10(2):22-28.
Abstract:A. C. Method began to be applied in the geoelectrical observations by using a set of equipments of type Mark-4 with accuracy of 10-3 in 1976, The results of experimental observations in terms of A. C. Method are presented in this paper as the following:
(1) The results from A. C. and D. C. method are agreeable.
(2) Signal-to-noise ratio can be increased in one digit number.
(3) The accuracy of A. C. method is 10-3 but D. C. method is 10-2. The resistivity anomalous of precursor phenomena up to 1-2% may be determined.
(4) For same depth, power consumption may be decreased by A. C. method.
1988, 10(2):29-34.
Abstract:Based on the seismic data during 1900-1985, this paper discusses some features of great earthquakes(M ≥ 7.0) activities in western China and its vicinity. Finally, the physical mechanism of results and its application in the earthquake prediction are discussed.
1988, 10(2):35-47.
Abstract:In this paper, the fundametal characteristics of the geological structures of the Hexi corridor basin and the recently active features of the fault at the northern flank of the yumushan mountain and Shanglongwang fault at the eastern flank of the yumushan mountain in its middle segment have been discussed. The research result has indicated that
(1) The Qilian mountain range is a nappe that moves to the northeastwards. It is estimated that the distance moving to the northeastwards is abont 4-5 kilometers since the middle Pleistocene.
(2) The NWW fault belt located at the north flank of Yumushan mountain takes overthrust as the dominant factor and cuts the deposits of the later part of the late Pleistocene.
(3) The activity type of the NNW Shanglongwang fault belongs to the type of the right strike slip accompany with the pressure. The geologicol and micro geomorphic evidences show that there have occurred 4 times earthquakes with the magnitude 7-8 in this fault since 25000yr. ago, and the latest one of them occurred at about 13300yr. ago. About the reoccurrence interval of the 4 times paleothquakes, they are nonuniform, namely, there are either the big or the small interval in this fault.
1988, 10(2):48-55.
Abstract:This paper studies premonitoring ability of seismic network in Shaanxi, Gansu, Ningxia and Qinghai area in detail and drew figure for premonitoting ability. It provides basis for selecting lower limit of magnitude. Finally, this paper offeres proposals of adjusting stations in above mentioned four areas.
Ma Shutian , Wang Biquan , Wang Yuxiu , Yang Jinying , Chen Zuyin
1988, 10(2):56-62.
Abstract:The Modified Hierarchical classification Method is used to divide seismic active periods of Northern China in this paper. The seismic active periods divided are better when the distances between classes are increment of square sum of deviation and the distances between samples are Euclidean Distance than that when the distances between classes are any kind of method mentioned in the paper and the distances between samples are resemblance coefficient. The methods of predicting seismic active peroids and selecting features are proposed, and they are used as well. After features are selected by our method the classification results can be improved and the posterior prediction made are consistent with actual state basically.
Yan Yuding , Chen Enmin , Huang Yongyin
1988, 10(2):63-70.
Abstract:The three-dimensional photoelastic simulating experiments to tectonic stress field of great Qiongzhou earthquake of 1605 are made. The results indicate that the maximum shear stress and principal compressive stress are mainly concentrated in the depth of about 20km where the NNW trending Tashi-Yanfeng fault is intercepsted by the NEE trending. Guangcun-Puqian deep fault. The Qiongzhou earthquake of 1605 is formed in the intercepted region. Because of the influence of the vertical force, the stress vector diagram shows obviously a feature of the fault-block type dip-slip subsidence in the east of Tashi-Yanfeug fault (a narrow belt near Dongzhai port), and a feature of the fault-block type subsidence in the north of Guangcun-Puqian fault (from Puqian bay to the south of Qiongzhou strait), respectively. The results of tests are consistent with field survey as well as the analysis and calculation based on the other data.
1988, 10(2):71-79.
Abstract:为了扩充北京地震台网的实用功能,为研究地震提供更多的有用资料,我们在北京台网利用数字地震波形记录,开展了常规的近震波谱分析,编辑出版了"北京地震台网地震波谱和震源参数观测报告",并开展了一些应用研究。
1988, 10(2):80-83.
Abstract:在地震分析预报系统的现代化建设中,计算机软、硬件的建设始终是核心。所谓现代化的含义之一,就是地震分析预报的人-机-体。硬件部分,主要是以计算机为中心,配备图像、声像显示的现代化视听设备。
Li Liuyu , Jin Ming , Jiang Xuyuan
1988, 10(2):84-86.
Abstract:许多关于岩石样品和模拟岩石样品的实验结果都证实了,在样品破裂前波速有一个明显的变化过程。但由于实验设备和技术所限,绝大多数实验样品都是比较小的,其尺度一般仅在几厘米到十几厘米,与野外实际情况相差较大[1]。
1988, 10(2):87-88.
Abstract:一次强烈地震所造成的灾害,主震的作用固然很重要,但强余震的作用也不能忽视。研究强余震的发生规律,对主震发生后的余震序列预报,减少地震造成的损失有一定的意义。本文拟通过对1605年琼山大震强余震的研究统计,来探讨海南岛强余震发生的规律,为今后海南岛的地震预报和防震抗震提供参考依据。
1988, 10(2):89-91.
Abstract:Based on the Asperity model and the Barrier model, another heterogeneous model-Obstacle model is proposed in this paper. The research of numerical modelling is taken for this model. The results show that on the fault plane where there are obstacles, the rupture expansion is related to the spreading speed of rupture, the area of initial rupture, crack types and the medium of the fault which contains obstacle. It also verifies that the rupture can cross or detour higher strength or/and bigger size obstacles, and then makes obstacle fracture again after a period of stress accumulation process under the condition of confining stress. Besides, it also proves the experiment results of imitated obstacle under uniaxial compression which we took before.
The possible genesis of the Haicheng and Xingtai earthquake sequences are explained, and some reasonable consequences are made through the research of the properties and effect on obstacle in earthquake source area.
1988, 10(2):92-104.
Abstract:A model system of earthquake prediction and countermeasure is designed. The necessaries, conditions, designed ideas, constructions, functions, compositions of the model system and applied mathematical methods are discussed in this paper.
Sopyright:China Earthquake Engineering Journal