Table of Content

08 March 1995, Volume 17 Issue 1

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Brief Report

FAULT BLOCK MOVEMENT AND SEGMENTATION OF ACTIVE FAULT

He Honglin, Fang Zhongjing

1995, 17(1):  1-6. 

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The behaviour of faults,which are the boundaries of fault block,is closely related to the movernent of the latter. Analysis of the relationship between the fault block movernent types and the fault activities and segmentation,as well as that between fault block movement and structural barriers is carried out in this paper.

AE b-VALUE DYNAMIC FEATURES DURINE ROCKMASS FRACTURING AND THEIR SIGNIFICANCES

Zeng Zhengwen, Ma Jin, Liu Liqiang, Liu Tianchang

1995, 17(1):  7-12. 

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Full waveforms of acoustic emission(AE)events were recorded during uniaxial compression of rockmass specimens with different structures. AE b-value of every 50 successive AE events was calculated.By scanning all AE events,a curve of b-value dynamic behaviour,i.e. b-value dynamic curve,of each specimen was obtained. According to the variation and evolution mode of b-values and the shape of the curve,two types of b-value dynamic curve,the hill-shaped and the step-shaped,have been distinguished.The hill-shaped b-value curves occured in intact specimens and correspond to progressively stable fracture and propagation. The step-shaped b-value curves tookplace in specimens with planar dis-continuities or heterogeneities,showing abruptly unstable fracture and propagation. In this case the term of fracture phase was suggested to describe the fracturing process.

ANALYSIS OF HONGTONG 1303 M8 EARTHQUAKE PROCESSES

Song Huizhen, Lan Yingang, Xu Pengfei, Sun Junxiu, Zheng Fudeng

1995, 17(1):  13-24. 

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Available are a lot of data about the slip rate for the Huoshan fault and the dislocations associated with Hong tong 1303 M8 earthquake and the Cenozoic activities are investigated for the Linfin basin. In this paper,Huoshan fau It plane is taken as dislocation plane。The stress rates and strain energy rates corresponding to the fauIt creep in pre-seismic period and the fault dislocation in co-seismic period have been calculated by means of the finite element formula of dislocation model in viscoelastic medium. Three results have been obtained:(1)Prior to Hongtong 1303 earthquake,he stress and strain energy rates are the highest for the southern section of the Huoshan fault in the Linfin basin,suggesting aaccumulating process.However,the minus rates are the highest in co-seismic period,suggesting a relieving process。(2)Hongtong 1303 earthquake speeded up the accumulation of strain energy for Linf in 1695 earthquake.(3)Application of split node technique in fimite element analysis to discreteness of the dislocation planes is in agreement with the dislocation concept.

INVERSION OF DEEP SLIP OF INCLINED-FAULT FROM GEODETIC DATA

Liu Jie, Song Huizhen, Wu Yingxiang, Liu Guimei

1995, 17(1):  25-31. 

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In this paper,according to the calculating formula for the surface displacements related to an inclined,shear and tensile fault,an inverse model of inclined fault has been established,by use of Segall and Harris＇method.A FORTRAN program has been given also,by which the deep slip rate and deep slip value of different attitude fault in different motion components can be inversed.So,the slip rate of two faults in Beijng area have been calculated.The activity of main active faults in Beijing area are well coincident with the regional stress field and fault stress field.

FUZZY MODEL DISCRIMINATION OF SHORT-TERM AND IMMINENT EARTHQUAKE PREDICTION

Li Minfeng, Ma Zongjin

1995, 17(1):  32-34. 

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A method for a decision to make short-term and imminent earthquake prediction using fuzzy model discrimi-nation is given in this paper.On the basis of seismic disaster database and the research on seismic disaster prediction and scientific division of disaster degrees we can make a reasonable decision on short-term and imminent earthquake prediction.

STUDY OF DIFFERENT-STAGE QUATERNARY TECTONIC STRESS FIELD FOK THE XIANSHUIHE FAULT ZONE

Xie Furen, Zhu Jingzhong, Shu Saibing

1995, 17(1):  35-43. 

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By use of fault slip data in invesion of using different-stage tectonic stress tensors,we have obtained two stages of tectonic Quaternary stress field of the Xianshuihe fault zone. In the first stage(from early-mid Pleistocene),the tectonic stress field is characteristic of NE-SW compression. In the second phase(from late-Pleistocene to the present),the tectonic stress field is mainly characteristic of nearly E-W compression and nearly S-N extension. In this stress field,the Xi-anshuihe fault mainly shows a left-lateral slip.

PALAEOEAKTHQUAKE TRACES ALONG THE SOUTHERN BOUNDARY FAULT OF XUANHUA BASIN,HEBEI PROVENCE

Ran Yongkang, Wang Jingbo, Peng Shizheng, Deng Qidong

1995, 17(1):  44-46. 

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Excavation of trenches revealed three palaeoseismic events along the southern boundary fault of Xianhua basin. They occurred in 8.54 ka,7.08 ka,and 5. 31 ka B.P.,respectivly,The average reccurence interval is1 615±360a. The displacement of three events are 0.55～0.74m,0.52～0.7m and 1.63～2.2m,respectivly.However,the event displacing the surface has not occurred since 5.31 ka B.P.,suggesting that reccurrence interval of palaeoearthquakes is not simply quasi-periodic.

ANALYSIS OF VELOCITY STRUCTURE OF THE CRUST IN THE EASTERN PART OF YANGTZE-NANHUA TECTONNIC REGION

Wu Jiansheng, Lao Qiuyuan

1995, 17(1):  47-51. 

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Studied in this paper are eight types of velocity structures of the crust in the studied region that can be distinguished,the relationship between the velocity structures and tectonic units of the crust as well as the geological implication for the different velocity structure types. Mean-while,the authors indicate that the low-velocity layers existing in the studied region occur at dif-ferent levels and have their small thickness and extension. Hence, they are unfavourable for de-velopment of large-scale basement detachment and lohg-distance overthrusting in an orogenic episode.

NEW EVIDENCE FOR ACTIVE FAULT ALONG THE NUJIANG SUTURE ZONE

Wang Yipeng, Ren Jinwei, Ye Jianqing, Shen Jun

1995, 17(1):  52-53. 

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THE RELATION BETWEEN VARIATIONS IN CONCENTRATION OF TRACE ELEMENTS AND SEISMIC ACTIVITY

Hu Yutai, Zhang Yusong, Li Jianhua

1995, 17(1):  54-58. 

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The contents of Al,Si,Fe,Mn,Zn and La in the hot water show a great amplitude of anomalous and trending variations prior to moderate and small earthquakes occurring along the faults and their adjacent areas,the patterns of which may be controlled by the coseismic stress fields and local geologic structures. However,the time sequence the amplitude of the anomalies related to appearing anomalies may be controlled by the chemical properties of the elements and their partitions. These elements in questions are easy to form parts of the colloid in the hot wateror to be absorbed bv the colloid.which are more sensitive to the medium than other ions andcomplexs,the anomalies in question can be regarded as an indicator of the occurrence of earth-quakes.

PRELIMINARY RESEARCH OF THE ANOMALOUS FAULT SOIL GAS FOR THE TAYUAN FAULT AND ITS ABILITY OF RELATING TO EARTHQUAKE AS WELL AS ITS MECHANISM

Kong Lingchang, Li Qiuzhen

1995, 17(1):  59-62. 

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SURFACE EFFECTS OF WAVES NEAR-FIELD OF SHALLOW EARTHQUAKES IN THE SANXIA AREA

Ma Wentao, Hu Yuliang, Chen Xiancheng, Yang Qingyuan, Hu Ping, Zhao Meng

1995, 17(1):  63-68. 

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From the near-field observation of microearthquakes and available data,it can be found that the amplitude of displacement decreases with the epicentral distances. The analysis of S-wave spectrum in the digital records indicates that the Goner frequenty is as high as up to 21.9 Hz, with its maximal power spectrum ranging form 0.5-26 Hz, and that the distribution of seismic intensity,epcentral intensity and the longth of major axis of isoseismic line shows certain dispersion,which results from the effect of the near-field surface. Study of these characteristic effect in question can provide a base of earthquake-proof/resisting engineering for economic construction.

PALEOMAGNETIC RESEARCH ON THE PHANEROZOIC TECTONIC EVOLUTION OF CHINA

Cheng Guoliang, Sun Yuhang, Sun Qingge, Wang Lihong

1995, 17(1):  69-78. 

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Synthetic Phanerozoic appanent polar wander paths for the North China,Yangtze and Tarim blocks are obtained by averaging paleopoles distributed in a small area for a defined geolog-ical time of a block.This area contains not only most of higher quality paleopoles but also some lower ones.Base on the synthetic APW paths and considering tectonics,paleontology and global geo-graphical reconstruction,we suggest that the North China,Yangtze and Tarim blocks were lo-cated along the lower paleolatitudes near the Eastern Gandwana during the Cambrian,With the clockwise rotation of global main continents in the Paleozoic,the Gandwana moved southwards to the middle-high paleolatitutes of the southern hemisphere and three stable blocks of China were separated in turn form Eastern Gandwana. In the Late Paleozoic these blocks and terraneswith Cathavsian flora were located on tropical or relatively low paleolatitudes. Clearly,they be-long neither to Gandwana nor to Laurassia. Rather they might be distributed in the middle Tethys as an independent assemblage.The collision and weld of the three blocks of China took place from the latest Permian to the late Jurassic. North China and Mongolian blocks had joined by the Permian before they accretedto Siberian plate. This accretion did not take place until the Cretaceous,when the basic frame-work of Eurasia was formed.

AN OBJECTION TO JIAONAN GRORP

Ji Zhuangyi, Zhao Huanjin

1995, 17(1):  79-85. 

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On the basis of the study of metamorphic rock in the Jiaonan group along the northern Jian-su～southern Shandong area,along with the data of the characteristics of boundary rocks,lateral undiscontinuity,types of rocks,correlation of rocks and the isotopic dating,the authors suggest that the group in question is not for the implication of single strata unit and is embeded between the Wulian-Rongcheng fault and the Haizhou-Siyang fault.The former contains three tectonic levels,its formation being presumably related to the opening／locking of the deep-seated bound-ary faults instead.

A METHOD FOR THE STUDY OF MINERAL INCLUSIONS AND ITS APPLIATION IN EVALUATION OF REGIONAL STABILITY

Chu Tongqin, Luo Guoyu

1995, 17(1):  86-88. 

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THE ACCURACY ESTIMATION IN THE INVESTIGATION OF DISASTER BY AIRBKORN REMOTE SENSING

Cheng Jiayu, Yang Zhe, Tang Hanjun, Wang Gongxue

1995, 17(1):  89-95. 

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Statistics of the size of the major earth quake disastrous targets in the past 30 years and the probabilities of targets in different size were conducted.The probabilities of interpreting the dis-astrous targets from different scale of aerial photograph were made on the basis of the visual in-terpretation. In order to meet the need of the disastrous investigation and lose estimation,the in-troduced scales of aerial photograph for the investigation in urban,countryside and rural areas are 1:10000,1:20000 and 1:30000 respectively,which should be adjusted by local terrain condition and the economic development.The error sources in the investigation by aerial photogropy were discussed,and the accuracy for major disastrous targets is more than 80%.