Abstract:Based on the "stereoscopic model", we computed a few simplified geological models using 3-D viscoelastic finite element method in this paper, discussed the effect of deep creep fault on shallow fault activity in crust and the process of controled and adjusted shallow stress field by the deep fault. The results show that the stress field in shallow can be increased and the stress acumulation or slack can be accelerated in fixed direction and fixed trend fault by creeping function of deep, Based on above, we explained the migration problem of seismic epicentre along a straight line and discussed the mechanism of repeat occurrence of large earthquakes.

Abstract:Based on reference[1], the numerical experiments, its processes and results of the imaging for the seismic velocity structure of upper mantle in the northern portion of North-South Seismic Belt, using the ART Method, are discussed in detail. It is suggested that in the present case of station distributions and its observational precision, satisfactory imaging results maybe obtain ed, using natural earthquake data recorded by stations located in and near studied region, and that in inversion calculation, the crustal velocity model as well as the selecting of the Moho dip angle are the important factors associated with the quality of imagine directly.

Abstract:After analysing the data of annual precipitation and the destruc tive earthquakes (M≥7.0) in mainland of China during 1951-1988, the following conclusion is obtained. When the earthquake(M≥7.0) occurred during last year October to next August, the seismic center area will be wet (more precipitation)in this year and appeared as drought last year. So the order of three biggest disasters is as "drought——earthquake——flood". The relation between the seismic swarm and precipitation is also analysed. Finally, from the variation of the geothermal flux, the possible causes of more precipitation caused by earthquake are preliminarily analysed.

Abstract:In this paper, the anomalous changes in radon content recorded by nine monitoring sites before ten moderately strong earthquakes occurred along the northern segment of NS seismic zone are analyzed. Further studying the temporal and spatial distribution characters of seismic and aseismic anomalies in the area, total anomaly frequency, time difference between the beginning and ending of anomalies etc., it is found that, in general, the seismic anomalies are characterized by "synchronism" or "cluster" and that the most of "scattered" anomalies are aseismic. Based on the above-mentioned results, the method predicting time, location and magnitude of future shocks using radon anomaly is also proposed.

Abstract:This paper introduces the method determining the normal dynamic curve of radon content in groundwater every year. And using the normal bynamic curve of every year and five-day standard deviation, the method evaluating observed datum quality of radon content in groundwater is proposed.

Abstract:Recently some scholars think that in the crust the stress probably causes slow plastic deformation wave, and consider that this deformation wave is significant in process of earthquake pregnancy, However, it is difficult to observe this deformation wave both in nature and in laboratory. We proceeded some field tests of large Scale samples to explore the existence of this wave. The tests were proceeded in rock body of fault zone. The test bodies of which size is 50×60×30cm⁸, were made in tunnels, The frictional surface is layer of nature fault gouge. The tests show that during loading the yield time of gouge is not identical. The gouge near the loading end yields first, then the yield scope expands progressively. This process corresponds with the propagation of plastic deformation wave in fault gouge. The measured velocity of plastic deformation wave is about 2-3cm/min, it corresponds to 10-16km/year.

Abstract:In this paper, the effects of SO₂ gas which is a main composition in earthquake premonitory sulphureous ground gases on the behavior in mice, earthworm and budgeriga (Melopsittacus undulafus L.)are discussed.
The experiments show that in mouse and earthworms some behavior responses are exhibited under the action of SO₂ gas at 50 ppm, and at 100 ppm, they present behavior responses, such as frequent actings and escapings and so on. In budgerigas, the calling frequencies present relatively obvious abnormalities under the action of SO₂ gas at 100 ppm, and at 400 ppm, the calling frequencies remarkably decrease and the behavior responses, such as dull-looking, spreading plume and swinging head and so on are presented. Spilling sulphureous groundgases prior to earthquakes may be a main factor exciting behavior responses in rats living in holes, earthworm living in underground and budgeriga with sensitive olfaction.

Abstract:For a vertically inhomogeneous layered model, Fourier-Bessel integration transform is applied to the equation of wave propagation, after that a synthetic seismogram can be obtained by a finite-difference iteration in the wave number domain. Due to the separation between space and time variables after the transform, such algorithm is of stable and wide feasible. In the present paper some models involving a lower velocity layer(LVL) and a higher velocity thin-layer are studied for comparison. Through an analysis for wave propagation in space and time domain, the processes of propagation and generation of several prominent phases are revealed. Computational results indicate that no matter how much the thickness of higher velocity layer is the reflection wave is still strong, while the initial head wave from the thin-layer is not obvious. It is worthwhile to point out that there exists one kind of converted head wave in the thinlayer. It is found that the upward propagation wave with strong energy is hard to be formed at the top of LVL, which means that there is rather serious uncertainty at inferring the depth of LVL.

Abstract:Under the non-uniform grid, method and calculating process distinguishing potential seismic source are proposed using the improved consecutive Hmmaing method. The calculating results show that this method can avoid some problems caused by the shape of potential seismic source area and the distribution of spatial parameters, and it is suited to different structures which have different strikes and different grid shapes.

Abstract:根据甘肃区域地震台网和全国地震台网测定,这次地震的基本参数是。

Abstract:Holographic photograph is applied to study surface deformation of core-contained rock samples under single-axial pressure and visible image of off-surface displacement field is displayed. When load is 90% of the critical value, strong deformation zone and macroscopic cracks appear around cores. Such zone may be found on one side of the core, if the strength of core is below or equal to that of the peripheral material. If the strength of core is above that outside, deformation inside the core may be small in contrast to outside.
Based on the experimental results, a new explanation of 'gap'formation before earthquakes is proposed.

Abstract:In this paper we have discussed the relations between the hydraulic diffusion, reservoir-induced earthquake and dynamic geological conditions in hydrology. We suggest that the hydraulic diffussion is main cause of reservoir-induced earthquake. We have also constructed two iducedfocus models associated with the hydraulic diffusion——nonstress increasing model and stress adjusting model, and proposed conditions and method of applying those models in prediction of reservoir-induced earthquake.

Abstract:Using the theory of consolidation and Boussinesq solution, the additional stress field, displacement field and over-pore-pressure field are calculated under the water-loadings for Danjiang Reservoir. The water levels are assumed to be 130m and 15km and the depth of bedrock body from reservoir bottom is 1, 3, 5, 7, 9, 11, 13 and 15 km respectively. The results show that:(1) the maximum values of σ₁, σ₃,τ_max appear at the centre of reservoir and the smaller values of σ₁,σ₃, σ_max, appear at the reservoir bank; (2) both σ₁ and σ₃ at the centre of reservoir are compressive and σ₃ near bank is tensile; (3) the maximum vertical displacement (7cm) occurs at the middle of reservoir and the maximum horizontal displacement (0.6cm) at the bank; (4) the maximum over-pore-pressure generally appears at the deepwater region of reservoir from 3km to 9km below the reservoir bottom; (5)the volume strain forms a compressive region at the centre area of reservoir, and a tensile at the bank area and expands in all directions being consistent with the distribution of epicenter of induced earthquake.

Abstract:目前地震预报还没有过关,单靠某一个前兆观测台站和某一种前兆手段来预报地震都不是很准确的。因此,利用多个台站、多种前兆观测手段来预报地震就成为提高预报准确率的一种重要途径。

Abstract:郯-庐断裂带是我国东部的一条著名的深大断裂带。它与地震活动的关系一直是人们研究的重要课题。

Abstract:公元前70年安丘7级地震发生于郯庐断裂的渤海和郯城两个强震活动段之间。

Abstract:近年来,笔者对全球、中国、中国大陆、华北、云南、四川、台湾以及日本等不同地区地震的时间分布进行了研究,提出地震的时间间隔△T与其出现频次N_△T之间存在两种分布关系^[1-4],即。

Abstract:

Abstract:根据甘肃区域地震台网和全国地震台网测定,此次地震的基本参数是。