1987, 9(3):1-10.
Abstract:In this paper, the author gives and analyses the forms and characteristics of the plane harmonic waves in the medium model founded by Men Fulu in which the effect of the viscosity of the fluid has been discussed. It is found out that there are four kinds of plane wave in the medium:first P wave, second P wave, first S wave and second S wave, which are all nonhomogeneous waves. And there are interference effects among them. Their attenuation and phase velocity are determined by the medium parameter, frequency, boundary conditions and source.
It is discussed in detail that P wave and SV wave are incident on the medium Ⅱ, seimispace of the porous medium, from the medium Ⅰ, elastic seimi-space. When SV wave is incident on the medium Ⅱ vertically, some numerical results have been obtained. The theories of propagation of wave in porous media have some significance for observing and explaining precursors of earthquake especially for oil exploration. The effect of viscosity of fluid that the second S wave is simulated must be considered in some acoustic fields and supersonic analogous experiment.
1987, 9(3):11-17.
Abstract:In this paper, the slip-softening model of earthquake instability on a strike-slip vertical fault with infinite length has been analysed by the finite element method. The effects of fault parameters on instability and precursors have been researched when there is softening phononous on both stiff and soft regions of fault. Relations between softening low of frictional stress and earthquake prediction, have been analysed, The process of changes in displacement, strain and stress fields before and after instability has been discussed.
1987, 9(3):18-22.
Abstract:The cause of earthquake is a complex problem. Perhaps, the combined efforts of many branches of science would contribute to the study of cause of earthquake. In view of the train of thought, the author tried to discuss the cause by using "localizability" model, based on the theory on non-equilibrium statistical physics developed in the 1970s.
1987, 9(3):23-30.
Abstract:A method of determining and examining earthquake risk region has been developed in this paper. After a strong earthquake, the energy propagated to the neighbourhood, It will become a triggering force to another earthquake in neighbouring region. Under the effect of the triggering force, the small and moderate earthquakes may easy occur in the low strength medium region, but in the high strength medium region the earthquake isn't easy to occur. Thus, the seismic gap may be shown by the small and moderate earthquakes. The high strength region (or seismic gap)can be regarded as future earthquake risk region. We can also examine the truthfullness of the seismic gap using the other earthquakes in succession.
Yu Xuejun , Yao Lixun , Gu Jinping , Sheng Guoying
1987, 9(3):31-38.
Abstract:The stress within Chinese continent plate results mainly from the compression of neighbouring plate, therefore, the seismicity within the plate has a direct bearct on the movement of several large plate around it. The strong seismicity along boundary of the plate is a clear signal of the plate movement. In this paper, the correlation between the strong seismicity within Chinese continent and the strong seismicity around it have been researched in time, space and magnitude of the earthquake. The method and indexes estimation earthquake situation also have been advanced. Furthermore, from the indexes we drew the concrete inference of the future earthquake situation in Chinese continent.
Tian Shaobai , Guo Daqing , Liu Guangyuan , Wang Wei
1987, 9(3):39-44.
Abstract:In this paper, the formulas estimating aquifer parameters have been reduced. From well tide observations of well No. 6 in Gansu province, the author calculated rocky porosity n, well-aquifer equivalent volume, rocky, elasticity modulus Ea and sensitivity η for using the well-aquifer as strain instrument. Changes of these parameters might reflect the changes of subsurface rock structure and strain case. It is significant to study these changes for predicting earthquake.
He Mingjing , Hu Mengchun , Lu Lian
1987, 9(3):45-50.
Abstract:The staged feature and directional migration of the Quaternary tectonic activity along the major fault belt in the southeast of Weihe Basin have been tentatively discussed according to the information from field prospect.
1987, 9(3):51-56.
Abstract:The causes of snakes leaving their holes before the Haicheng M=7.3 earthquake of February 2, 1975 have been analysed using experimental result about sensitivity of snakes to radon. It is believed that, besides the established "thermal anormaly", snakes may be sensitive to radon.
1987, 9(3):57-62.
Abstract:The fault-block structures are well developed in the coastal area of Fujian province. The boundary of the area is the Minjiang River and the Jioulong River. The differential movement of fault-blocks since neotectonic period may be divided into three regions, i. e. thenorthern, the southern and the middle. The preparation for 1604 Quanzhou earthquake is considered to be conform to the combinatorial model theory. The middle fault-block is corresponding to its accumulation unit of stress, the northern and southern fault-blocks are corresponding to its adjustment units of stress. They have quite different respectively. The preparation process of the earthquake is divided into several periods, and the patterns of stress effect and analyzed.
1987, 9(3):63-70.
Abstract:It is presented that the numerical experiments about effect of the deviation of crustal model used in location on determining focus. Which results show that the model errors affect mainly the depths determination of shallower earthquakes in upper crust, whereas their effect on events in lower crust is few. The shocks determined will be deeper than that of actual ones when model used in location is simpler than that of true structure, on the contrary, the real depths will be deeper than that located. The deviation of total crust thickness will make focu depths calculated a system error which is in close proximity to the thickness deviation. Depths determined with a common model contain the relative accuraty, otherwise they is imcomparable. Finally, the experiment results is discussed briefly.
1987, 9(3):71-77.
Abstract:Active Zhongwei-Tongxin fault is a regional great fault belt located at the northern foot of Xiangshan Mountain. This fault is the east segment of large Tianzhu-Tongxin fault belt, its length is about 150km. The segment consists of a series of discontinuous faults. On October 14, 1709, a great earthquake(M=7.5) occurred on the segment in the south of Zhongwei. All strata singe the latg Epipleistocene cut by the fault, the offset is 25±3m the average slippins rate is 2.5mm/yr.. Since about 6000yrs. B. P. 3 great earthquakes (M≈7.5)have occurred on the fault. The average recurrence interval of the events 2299 yrs. The average recurrence interval obtained from the method of micro geomorphology is 2100 yrs.
1987, 9(3):78-83.
Abstract:In the paper, according to the data of more than two hundred of drill holes in the region of Xian, the author divided 16 kind of combinations of soil layers and calculated the surface maximum accelerations and response spectra of accelerations of all kind of combinations with the method of Wilson-θ. The changing rules of the earthquake motions following the change of the combinations were studied. The contour map of the surface maximum accelerations and the map of the distribution of response spectra was drawn. Contrasting the maps with the topographic map, author concluded that the topographic units control the distribution of earthquake motions regionally and that the combinations of soil elasls in the topographic units control earthquake motions concretely. The results could be used in earthquake microzonation directly.
1987, 9(3):84-91.
Abstract:This paper presents a detailed analysis on the pattern of drainage systems and the geological structures along the Red Piver Faults and its eastern adjacent area. Together with the results about the earthquake mechanism proposed by precursors, it is pointed out that the stress field in the studied area has been changed since the neotectonic period.
Briefly, before the middle time of the early Pleistocene the compressive stress axis was approximately east-west trending, while in the middle Pleistocene it was northwest-southeast trending. After this, it has turned to northwest north-southeast south trending.
The stress field inferred from the pattern of drainage systems is consistent with the stress field obtained from geological analysis and earthquake mechanism data. This shows that the analysis of drainage systems is a useful approach for this type of research in this particular area.
1987, 9(3):92-98.
Abstract:The triaxial experiments of rock mechanics completed recently show that rock failure can be caused not only by increasing of maximum principal stress, but also by change(increasing or decreasing)of intermediate principal stress and by decreasing of minimum principal stress. Concerning that earthquakes are rock failure under triaxial stress state in the crust, it is pointed that earthquakes can be caused not only by increasing of maximum principal stress, but also by decreasing of intermediate principal stress or minimum principal stress. Before earthquakes there must be a process of increasing of stress or renergy, but earthquakes mustn't happen in the process of increasing of stress or energy. Earthquakes can happen in the process of decreasing of stress or energy. The action which can cause the stress decreasing in the crust was discussed, and the possibility of earthquakes caused by stress decreasing was searched by seismic activity.
1987, 9(3):99-102.
Abstract:作者曾在文献[1]、[2]中对新疆6级以上强震活动的可公度性特征分区进行了初步研究,并对此进行了地震预报的实际检验。结果表明,利用强震活动的可公度性估计强震发生的时间有一定效果。
Gu Jinping , Yu Xuejun , Li Qinghe , Sheng Guoying , Min Xiangyi , Hou Xiaoyu
1987, 9(3):103-106.
Abstract:1986年8月23日门源6.4级地震前,地震波速度比异常从1984年起即开始出现,异常过程中由于受1985年7月14日冷龙岭3.6级地震的影响而略有回升,以后继续呈负异常,最大幅度达7%。震前在震中以西地区的波速比值未出现回升以后的明显高值,而震中以东的九条岭地区虽然长趋势波速比值负异常不明显,但震前的趋势上升及高值的出现却十分清楚。
1987, 9(3):107-110.
Abstract:工程技术的先进性包括两个方面,即开拓性(创造落后技术所不能创造的产品和成果)和合理性(用更少的物力和人力创造出更多的产品和成果)。在生产过程中,从经济上衡量工程技术的合理性是十分重要的。任何一种科学成果要付之于工程技术以期得到生产应用,首先要考虑其经济效果。
1987, 9(3):111-112,115.
Abstract:宁夏地区现今中强地震主要发生在南部的西海固地区和北部的灵武、吴忠一带。自1970年建立了前兆观测台网以来,共发生过4次5级以上的中强地震,即:1970年12月3日西吉5.5级地震、1971年6月28日吴忠5.1级地震、1982年4月14日海原5.5级地震和1984年11月23日灵武5.3级地震。
1987, 9(3):113-115.
Abstract:近年来,在我国天山境内发现了许多古地震遗迹(图1),现就几个古地震剖面介绍如下:
1.莫会察汗沟口古地震断层陡坎
在和靖县城以西,焉耆盆地的西北隅的莫会察汗沟口西侧(拔海约1800米),发育着三条大致平行的古地震断层陡坎。
1987, 9(3):116-118.
Abstract:天水地电台已有15年观测历史,但由于一直存在着较严重的干扰现象,直接影响了资料质量和预报效果。为了克服和排除这些干扰,我们用不同极距进行了对比实验观测,取得了较好的效果,据此提出了该台的改造方案,並已正式投入使用。
1987, 9(3):119-121.
Abstract:山丹地震是西北地区强震之一。前人已经进行过多次考察与研究工作1)2),但是对极震区构造背景、发震断裂特征的认识尚有一定分歧。本文利用陆地卫星多波段影象片,对1954年山丹7(1/4)级地震构造背景、发震断裂特征进行目视解译。
Sopyright:China Earthquake Engineering Journal