Abstract:By studying the fluctuation intensification of the ratio of small earthquakes modulated (r_m)and the abnormal area of the ratio of small earthquakes modulated (Sr_m) in the earth-quake source system before strong earthquakes. The following results are gained:
1.The fluctuation intensification of the ratio of small earthquakes modulated almost appears before strong earthquakes in the source and near source region or before medium earthquakes in near source region and when the fluctuated times are three, the strong earthquake or mediutn earthquake will happen.
2.r_m abnormal area (Sr_m) around source region shows the process from small to largearea and then, from large to small area before most.moderate earthquakes,therefore,we take the ratio of the minimum area of r_m anomaly to the maximum area of r_m anomaly as an index of the mid-short term earthquake prediction,according to statistics,the anomaly index[λ]is
λ=Sr_min/Sr_max,[γ]=0.32+0.09
In some earthquakes,the Sr_m fluctuation intensification appears before earthquakes,this may be regarded as the result of weak adjusting ability of adjustment units around the source region.
3.The beginning time of r_m and Sr_m fluctuation intensification has a connection with magnitude of earthquake,the bigger the magnitudes are,the earlier the fluctuation intensi-fication will appear.According to the statisties of the time (t) from the beginning of Sr_mfluctuation intensification to earthquake occurrence and magnitude (M),the following for-mula is obtained:
M=4.29+0.11t±0.33
4.There ordinarily appear three forms of r_m anomalies in the field region before strong earthquakes:random,fluctuating and declining.If there are three r_m fluctuation intensifica-tions, the strong earthquake will happen in the field.
5.By using the principle of autonomous system and unautonomous system,the fluctu-ation of r_m and Sr_m adjustment region around the source before earthquake is explained briefly.

Abstract:在地震预报研究中,地震学方法占有重要的地位。

Abstract:Based on the geological and geophysical data,this paper establishes a stereogeologic model of the Changma basin. The change of stress field and theearthquake mechanism be-fore and after the Changma Ms7.6 earthquake in 1932 are studied by 3-D finite element-method. The results show that:
1.The difference between the focal fault strike and that inferred by the principal com-pression stress is 65°,this probably is due to the block rotation which results from the force moment produced by the rotated principal compression stress in shallow crust and the NE directional principal compression stress in depth. The hinge point is the focal re-gion.The block rotation results in the differences between the mechanical and geometrical natures of earthquake fault and focal tault.
2.The Changma earthquake is due to the cooperative interaction of closing joint and block rotation.
3.The regional stress field discords with local stress field and the appearance of stress relaxation unit is probably relative tothe earthquake preparation and occurrence.
4.Nonuniformity of fault activity is positive correlative with the inhomogeneous dis-tribution of plane maximum shearing stress.The fracture zones are characterized by rela-tive levorotation, shove and compression,but the distribution of strike slip is inhomoge-neous.

Abstract:Based on the analysis of hydrogeochemical features of Uranium, in terms of the data of dynamic variation of Uranium in some springs in the western Yunnan and Hexi corridor, Gansu, this paper studied the relation between the content variation of Uranium in ground-water and moderately strong earthquakes in these areas.The result shows that the anoma-lous variation of Uranium content is obvious under some circumstances.
By analysing the anomalous mechanism of Uranium content in groundwater and the interference factors, it is suggested that the Uranium anomaly doesnot commonly occur be-cause of the differences of gochemical conditions around the springs, and only the springs with high content of activated Uranium in groundwater and wall rock are suitable to obser-vation of Uranium content.
with the method of comparative observation, the interpretation is tried, for the first-time,on the relationship between the content anomaly of groundwater Uranium and that ofgroundwater Radon,and on the mechanism of Radon anomaly in groundwater. The feasi-bility of earthquake prediction with groundwater Uranium anomaly is also dealt with.

Abstract:The periodic change of ground resistivity, which appears the square wave of‘one peak and one valley 'every day, is recorded by DZ-8 digital terrameter at Jiangninggeoelectric station. This paper describes the daily period-variation shape,and analyses the seasonal features and temporal features of daily variation by using time-distance square method. Be-fore the Xiaodanyang earthquake,Jiangning (M3.1,Δ=34km) on Sep.12,1991 and the Sheyang earthquake (M4.6,Δ=244km) on Oct.22,1992,the daily variation shape of ground resistivity disappeared,ten plus days after the earthquakes,the daily variation re-covered,showing obvious short-impending precursor.

Abstract:Based on the full understanding of characteristics of earthquake sequences,26 items of original features of earthquake sequences are selected from distinct views of physics back-ground. According to the Wallen scores of these original features, 11 items of original fea-tures which can prominently represent the characteristics of earthquake sequences are care-fully chosen as indexes. Using ISODATA method of fuzzy clustering,earthquake sequencesare classified into two categories:Type-Ⅰ sequences are these in which earthquakes with M≥5.0 occur in the same area within 3 months after an earthquake with M≥6.0;Type-Ⅱ sequences are these in which no M≥5.0 earthquakes occur within 3 months.The dis-criminating model of post-earthquake tendency has been built by using 22 known earth-quake sequences occurred in the China continent since 1966. Then, extrapolation tests are taken by using other 8 earthquake sequences occurred in China. The results indicate that this method has good effects on discriminating the type of earthquake sequences.

Abstract:In this paper,the authors applied the grey system prediction model of the grey system the-ory to set up respectively three grey prediction models (GM) of magnitude (M),epicentral dis-tance (R) and origin time (tf) versus apparent resistivity abnormal value (U) and lasting time (T).Because of introducing GM to avoid determining subjective statistical function,this modelis able to predict earthquake with less data at one geoelectric station,and afford different pre-diction equations for different stations. The Drediction effect is better than that of present someprediction equations, The advantages of this method are: requiring less data; simple calculation; clear result and practical.

Abstract:Before constructing a nuclear power plant, it is highly important to evaluate the capability of faults in its site area in seismology and geology sitings, The author studies the NUSS Codes and Guides, and combining with field fault investigation of the site area, further suggests that Donggang fault is a capable fault defined in the NUSS Codes and Guides(HAF0101).Howev-er,this is not a subversive factor for the recommended site. Because the faultis 4km from the site,the fault rupture at or near the ground surface will not affect straight the operation safety of nuclear reaction pile. Thus,it is considered that the site is satisfied with the demands of the NUSS Codes and Guides in China.

Abstract:Based on the historical earthquake data of the loess are in Northwest China and by using the fuzzy sets method,the fuzzy information relation between magnitude and isoseismal area in the loess area is established.According to the fuzzy relation,two recent earthquakes' isoseismal areas are examined,and the results are more corresponding to the reality than that using the least squares method. Finally,the results are compared with the former's.

Abstract:The disasters of landslides and slumps caused by earthquake have not been systematically studied since the 1927 Gulang M8 Earthquake occurred in Gansu Province. This paper, for the first time, intrduces the main features of the seismic landslides based on the interpretations of the air-photos and field investigation, and discusses the relation between the distribution of seis-mic landslides and the fault belt in the Gulang region.
The result has a certain meaning to analyzing the seismotectonic environment of the Gu-lang M8 Earthquake and forecasting the seismic landslide and land fall disasters.

Abstract:Based on analysis of the basic features of Laohushan fault zone,this paper discusses the segmentation of the active fault zone by using the natural, geometric, kinematic and rupture features of active faults as the segmentation principles.It emphasizes the rupture segmentation. The results show that Laohushan fault zone can be divided into 4 segments: Xijishui, Lao-hushan, Caoxia and Heimajuanhe segments. The segmentation can provide important informa-tion for mid-long term earthquake prediction.

Abstract:Tmis paper introduced the real-time processing system in micro-computer,using the hard-ware interruption and clock interruption and the technique that the programs can be stayed in a internal memory of computer. The system has foreground and background processing function; multi-channel programs can be run in the CPU of main computer at the same time;the real-time processing of the data collecting,event detecting,data dumping and earthquake locationetc. can be carried out.The system is suitable to the regional telemetric seismic network or the local telemetric seismic network.

Abstract:This paper briefly describes the principles,configuration and features of a practical pro-gram for the microcomputer management of the observed data. The flow diagram and simple instruction are given.

Abstract:当前在地应力观测分析工作中,普遍使用对电感原始测值曲线划定基线,从而确定异常的方法。

Abstract:1990年兰州地震研究所在青海祁连县建立了大地电场、大气电场、电磁幅射和地应力4种手段的综合观测台(简称祁连台)。

Abstract:1993年10月26日在甘青交界托来附近(Ｎ38°36',Ｅ98°42')发生了一次Ms6.0级地震。

Abstract:It is often observed that there are separated graben structures in the reactivated cratons where rifting occurred durig different poriods of their evolution. Some of these graberls behave as present-day active seismic zones,such as the Linfen graben, Shanxi,China; the Xingtai graben, Hebei, China; and the New Madrid graben, the United states. Increasing data have demonstrated that the causes of earthquakes in these areas are in-volved with many geological and geophysical conditions besides the active fauting.As a typical case,studies on the Luifen graben show that the seismogenic process is associated with the foliowing factors:(1)The metamorphic rocks with greater strength around the graben,in which stress is built up under the action of the regional tectonic stress field.(2)The medium of the seismogenic layer with lower strength at the depth range of 5 15 km within the graben,which ruptures during the seismic source process to release energy and radiate seismic waves. (3)The abnomal layer with low velocity or low resistance beneath the seismogenic layer,which has the ductle adjusting function to the seismic source process.(4)The fault zones along the both sides of the graben ,which are character-ized by mylonitization and have controlling effects on the process of earthquake brewing.The combination of these elements offers seismogenic models which can explain the causes of some seismic zones in the continental ar-eas associated with reactivated cratons and refting grabens.Numerical modeling has been used to test the pro-posed models.