Abstract:This paper theoretically discussed two kinds of pre-displacement stopping phases. One occurs in part area of fault, we call it partial area predisplacement. Another occurs in the whole fault, we call it whole area pre-displacement. There are obvious differences of stopping conditions between the two kinds of pre-displacements, which result in difference of pre-displcement stopping phases and difference of long-period wave as well as difference of sudden types of precursors induced by long-period wave. The preliminary results are as follows:
(1) The pre-displacement before the most of large earthquakes is partial area pre-displacement, but that before the most of moderate earthquakes whole area pre-displacement.
(2) The source process of partial area pre-displacement is finite moving source and that of whole area pre-displacement is combination of finite moving source and instantaneous source. The former only produce one long-period P-wave, but the latter produced two long-period P-waves with different arriving time.
(3) The long-period P-wave induced by partial area or whole area predisplace-ments is similar to their source time function. The former produced single peak type of precursor, the latter produced double peak type of precursor. So the magnitude of future earthquake can be judged approximately by type of precursors.
(4) Because extent of partial area pre-displacement region before large earthquake is approximate to extent of whole pre-displacement region before moderate earthquake, their pre-placement amplitudes is also approximate. Such results can explain the fact that the amplitudes of precursor is not related to magnitude of earthquake.

Abstract:The interaction between two intersecting strike slip faults is considered by the elastostatic dislocation theory. The two intersecting faults are taken to be situated in a homogenous, elastic half space. For simplification the following assumptions are made in this paper:(1) the stresses are independently calculated in an elastic half space, that is, when the stress produced by one fault is calculated, it is assume that the other fault is not existent; (2) These independent stresses are added up, thus analysing the interaction between two intersecting faults; (3) The depth of the two fault-planes is similar.
In this paper, the interaction between two intersecting strike slip faults with the types of Y, V, X, T and+according to the above assumptions. It is shown that the interaction related to the disposition in geometry, that is, the intersecting fault in different regions near the earthquake fault is differently affected and that the theoretical results obtained may be useful in the estimation of seismic risk and also in earthquake prediction.

Abstract:In this paper, we are rolling in damage data and the results of a laboratory tests. A set of predictable method that is satisfactory to China's Northwestern sites damage are established with the principles of information distribution, fuzzy multifactorial evaluation and information concentration. Site is classified into three sorts:stable region, stable region in the main and non-stable region. Evaluated paramenters are geography and geomorphology, soil liquefaction potential, loess settlement, the thickness of artificial filled soil, the depth of soft soil and slope stability. The damages of a few sites of Xian and Baoji Cities are evaluated by this method. And its results are in keeping with those of macrosopic analysis. This paper provide the prediction of China's Northwestern sites damage with a kind of quantitive research method. At same time, it is of importance to research of seismic microzonation.

Abstract:Based on the experimental study, the formation mechanism of radial fissures and small holes in quartz grains from active fault gouges is dealt with in this paper. A new standpoint, of which the radial fissures and small holes result from the explosion of inclusions in the quartz grains in the course of stick slip friction of the active faults, is put forward. The conclusion is that radial fissures and small holes in quartz grains can be regarded as a new mark identifying stick slip of active faults.

Abstract:In this paper, the direct computing results about electric sounding for three dipping layers are investigated. And the explanation of complication of electric sounding curve from obsurvatory is dealt with. The method of determination of the depth of electric layers is introduced.

Abstract:Some dynamic feature and effect of seismic waves by explosion are defined as seismic effects of explosion source. The methods and targets to appraise seismic effect of explosion source are put forward, including coherence function, converted coefficient of energy, attenuation factor of vibration time, spectra etc. The coherence function was introduced to analyse explosion for the first time. The physical principle and computational method of the aforementioned targets are represented. For the application, the experiment results of a certain charges are analysed and the data of the experiment shots from the DSS in the area from southwest of Shandong to north of Henan was dealt with, and they are basically identical. The method mentioned above will be useful for seismic exploration, seismic sounding, engineering seismics and seismic tomography.

Abstract:Reservoir induced seismicity is closely related with water permeating. The paper considers that the pre-earthquake activities in reservoir induced seismicity are mainly due to pore pressure diffusion produced by water permeating and the weakness of rock strength. As result of complexity of permeating property in underground rock beneath reservoir region, it is divided into two cases which are respectively homogeneous and inhomogeneous permeating in reservoir rock medium. Then, this paper has used the theory on pore pressure diffusion in porous media of solid-liquid two phases so as to calculate in numerical analog the pore pressure field produced by reservoir impounding. It is shown by calculated results that the distribution of pore pressure due to water permeating in inhomogeneous seeping models is corresponded well with the spacious position of reservoir seismicity. The time (1.8~45 days) of diffusion from peak of pore pressure to pre-earthquake focus of reservoir induced seismicity is about the same as the lag of the pre-earthquake activity produced by reservoir impounding.

Abstract:In this paper, the effect of radon in hydrofracturing experiments at the experimental area of the Tangkeng village ZK10 well, Nanging county, Fujian province is introduced. Water-radon and soil-radon changes with the increase of pressure. For example, the variable amplitudes of water-radon are 15%, 13.5% and 7.5% in the ZK12 well with the different pressure; variable amplitudes of soil-radon as +219% and +186%, -110% and -197% in the 1° and 4° observation point respectively.

Abstract:Applying the data of 7 artificial explosions we calculate the average crustal thickness and the average thinckness of the upper layer, and various seismic velicities in the area of southeast of Gansu, the north of Sichuan, the south of Shaanxi, the south of Ningxia and the northeast of Qinghai and the contiguous areas of Gansu, Sichuan, Shaanxi respectively. It is suggested that thickness on contiguous areas of Gansu, Sichuan and Shaanxi is quite close and the crustal thickness decreases from northwest to southeast gradually.

Abstract:Using the data from more than 100 meteorological stations, this paper preliminarily analyzes the effect on earthquake occurrences by the variations of atmospheric pressure field during the last two years or longer in the southwestern areas of China, yielding results show that when the 24-hour atm. variation in Yunnan area and its neighborhood (mostly in the Sichuan basin) appears a high value and then reaches a certain index) i. e. △P_ij=P_ij-P_i-1,j(i:date, j:month) we have:
△P_ij ≥ 1.4σ_j (j=Jan., Feb., …Dec.; σ_j=standard deviation). If a relatively low atm. pressure is also detected in the same period in Yunnan area, there might be possibility for occurrences of M_L ≥ 4.0 events in Yunnan region and its neighborhood. The 91.8% prediction accuracy can be maintained for earthquake occurrences within the following 7 days, and 84,5% prediction accuracy can also be reached for earthquake occurrences in the following 5 days. The epicentres of the earthquakes nearly all distribute appears the areas where the greatest strength of low atm. pressure, or it is on the shearing belt of the high-and low-atm. pressures.
Finally, the paper briefly discusses the possible connections between the above-mentioned two situations.

Abstract:In 1957, we studied a lot of historical records of the Jan. 23 1556 Guanzhong earthquake (M ≥ 8). We found two interesting records in the epicenter area:About eight hours before the great earthquake, people felt a kind of ground rotational movement and dizzied.We pointed out that is a kind of foreshock phenomenon^[1]. In 1971, the author and Qin Baoyan studied this phenomenon and considered that it is a slow motion which is useful for earthquake prediction^[2]3 In this paper, we intend to discuss the cause of the ground rotation before great earthquake. Besides, we also intend to discuss a significance of block rotation in earth-quake prediction

Abstract:作者在文献1)中曾提出"青海四川交界处的玛多-达日-玉树-甘孜范围内,在1989年(±1年)可能发生7.5级(±(1/4)级)地震"的预报意见。根据对三年多来全国地震活动形势和南北地震带中强地震的活动图象的分析,作者认为该预测意见所提出的强震危险性增强了。

Abstract:1987年1月6日凌晨,新疆拜城县境内发生5.9级中强地震,作者对这次地震进行了考察^*,现将这次地震的有关情况叙述如下。

Abstract:煤矿地下电气作业会在其周围局部地区造成一定的电磁干扰,但是对其影响程度目前尚未进行过较深入的分析和讨论。1970年宁夏石咀山市党校测点的大地电磁观测中曾发现过这种干扰,结果使该测点工作无法进行。1979年在甘肃山丹邮电农场测点亦发现此种干扰。1986年4月在山丹南湾测点上又发现了这种干扰。

Abstract:1987年在甘肃省境内发生了三次中强地震,这三次地震是1月8日迭部5.9级地震、9月12日张掖4.5级地震和10月25日礼县5.0级地震。我们根据甘肃省、青海省、陕西省地震台网以及全国部分基准台站记录到的P波初动资料得到这些地震的震源机制解。

Abstract:作者作出了1953年-1986年在日本发生的7级以上大地震的M-t图,发现了一个很有规律性的现象,即每隔5年的时间,就要发生一次7.3-8.1级的大地震,从1953年至1986年,共出现6个同样周期(图1)。