Table of Content

06 December 1989, Volume 11 Issue 4

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Brief Report

GREETINGS TO ALL THE SEISMOGEOLOGISTS ON THE OCCASION OF THE 40TH ANNIVERSARY OF OUR NATIONAL DAY

Editorial Board, Editorial Office of SEISMOLOGY AND GEOLOGY

1989, 11(4):  1-2. 

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CONGRATULATING PROF.MA XING-YUAN UPON HIS ENGAGING IN GEOLOGICAL RESEARCH FOR 51 YEARS

Editorial Board, Editorial Office of SEISMOLOGY AND GEOLOGY

1989, 11(4):  3-4. 

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RESULTS OF IMAGE PROCESSING OF AEROMAGNETIC DATA IN NORTH CHINA AND THE SEISMOTECTONIC INTERPRETATION

Yu Qin-fan, Ma Xing-yuan

1989, 11(4):  5-14. 

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The results of image processing of aeromagnetic data in North China are introduced, including pseudocolor enhancement, stereo shaded relief, convolution filtering, expon-tial filtering and local adoptive histogram equalization images. Based upon the information reflected by these images a comprehensive study of both the geological entities and their evolution and also the related tectonic lineaments has been made. Thus is established the seismotectonic framework of North China subplate. A model of block rotation in the strike-slip setting has been adopted to explore the mechanism of the tectonic deformation and seismic activity of the region.

HORIZONTAL DISPLACEMENT AND EARTHQUAKE RECURRENCE ALONG LUHUO SEGMENT OF THE XIANSHUIHE FAULT ZONE

Li Tian-sao, Du Qi-fang

1989, 11(4):  31-42. 

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The horizontal displacement, pre-historical earthquake traces and earthquake recurrent interval along Luhuo segment of the Xianshuihe active fault zone are discussed in this paper, The average slip rate of the fault since late Pleistocene is 13mm/a. The recurrent interval of large earhquakes since Mid-Holocene is less than 600 years.

FAULTED LANDFORMS ALONG THE XIANSHUIHE FAULT ZONE AND THEIR SEISMOLOGICAL SIGNIFICANCE

Qian Hong

1989, 11(4):  43-49. 

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Recent displacements along the fault will certainly produce pronounced markings on the landforms. Therefore, it is possible to acquire some important informations about seismic activity along active fault by using these land’ features-faulted landforms. Faulted landforms along the Xianshuihe fault indicate that the fault is characterized by intermittent earthquake displacements which follow the characteristic earthquake model for the recurrence of earthquakes with the same size at the same place. The pattern of the progressive evolution of offset streams might indicate that the slip rate of the fault in the same place is relatively constant during a certain period. Therefore, faulted landforms can be used as an important indicators in the research of seismic activity.

SEISMIC INFORMATION ENTROPY——ALSO AS DISCUSSION WITH MR.ZHU LING-REN

Xia Hao-ming

1989, 11(4):  50-52. 

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COMMENTS ABOUT THE PAPER“SEISMIC INFORMATION ENTROPY”

Zhu Ling-ren

1989, 11(4):  53-54. 

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SEM STUDIES ON THE FAULT GOUGE FROM JIANGYIN-JIADING FAULT ZONE IN SOUTHERN JIANGSU PROVINCE AND ITS SEISMO-GEOLOGICAL IMPLICATIONS

Zhou Ji-yuan, Duan Guang-xian, Gao Den-Hang, Pan Yang-wei

1989, 11(4):  55-62. 

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Based on the analysis of the macrostructural and microstructural features of the Jiangyin-Tiading fault zone in Southern Jiangsu Province, the surface textures of the quartz grains from the fault zone was studied by means of scanning electron microscope (SEM). For comparison, the same work has been done for the middle segment of Tancheng-Lujiang fault zone. By comparison and analysis of the results, the ralative age and activity of the Jiangyin-Jiading fault zone have been determined. In addition, the model of earthquake migration along the fault zone, the probability distribution for the surface texture of quartz grains from the fault zone and its seismo-geological implication have been discussed in this paper as well.

SYNTHETIC PROBABILITY METHOD AND ITS APPLICATION TO CHARACTERIZE THE SPATIAL AND TEMPORAL HETEROGENEITY IN POTENTIAL SEISMIC SOURCE REGION

Jin Xue-sheng, Dai Ying-hua, Ma Gui-hua, Kang Ji-cheng, Feng Hui-yun, Zhao Jun

1989, 11(4):  63-70. 

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Based on the recurrence rates of strong shocks, the spatial and temporal relation between small and moderate earthquakes and the occurrence of strong shocks, the gap in fault zone, the immunity of strong shocks as well as estimation of seismic risk in North China in the coming 5-10 years, the way of describing spatial and temporal heterogeneity in potential seismic source region is discussed. The weighed coefficients are defined to describe the spatial and temporal heterogeneity, as example, in several potential source regions in the north part of Hebei province. In combination with the Weibull distribution, different reccurrence rates in each year are obtained, which may be applied to seismic risk analysis.

FAULT FAILURE BY TANGSHAN EARTHQUAKE AND NUMERICAL ANALOGUE OF ITS MECHANICAL PROCESS

Wang Ji-cun, Xu Chun-rong

1989, 11(4):  71-76. 

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This paper discusses the mechanical process of earthquakes from its preparation to occurrence by the method of numerical analysis, taking the 1976 Tangshan strong earthquake as an example. We have analysed the mechanism of the causative fault failure in Tangshan region using the nonlinear finite element method.The mechanical process from the preparation to occurrence of the causative fault and the rock system around the fault are approximately simulated according to the time-sequence by the increment analysis method. The results are analysed and compared with the observed real earthquake data.

GREY ZONATION OF SEISMIC RISK IN SOUTHERN LIAONING PROVINCE

Huang Xue-fan, Zhong Yi-zhang

1989, 11(4):  77-82. 

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According to grey systematic theory, a grey zonation of seismic risk in southern Liaoning Province has been proposed in this paper, based on seven environmental factors such as seismicity,active fault,Bonger gravity anomaly etc.As a result,southern Liaoning Province has been regionalized into extremely dangerons, dangerous, less dangerous aud safe regions, respectively.

ESR DATING OF FAULTS IN THE AREA OF XIAOLANGDI RESERVOIR ON THE YELLOW RIVER

Chen Yi-jian, Zhao Po, Lu Jin-fen, Qiao Li

1989, 11(4):  83-90. 

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In order to check the applicability of ESR dating method to determination of the age of fault, 13 samples from fault gouges and calcretes were collected from five fault outcrops in the area of Xiaolangdi Reservoir on the Yellow River. The E’ signal of quartz grains from fault gouge, and the signal at g = 2.0000 and g = 2.0036 of calcretes from the loess deposits covered the faults were used for the assessment of AD value.To check the hypothesis that the ESR signal intensity was reset to zero by faulting, pure quartz sand were pressed to 17 kbar in a vessel. The result shows that the E’ signal intensity was decreased to 24 % of the original intensity. In addition, the AD value of the sample collected from the sliding face of the fault was decreased greatly compared with the sample collected from the normal position located five metres away from the fault zone. It indicates that the zeroing effect of faulting seems to have occurred but the ESR signal intensity was not completely reset to zero. The ESR age therefore, is considered to be a rough estimation of the period of fault movement.The measurement of samples from fault outcrops resulted in ages ranging from 0.154-0.532 Ma for the fault gouges and 0.098-0.348 Ma for the calcretes from the loess deposits covered the faults. It is in accordance with their relative chronology estimated from the geological field evidence. The determination indicates that the ESR method is a promising technique for determining approximate age of fault movement.

THE GEOLOGICAL ENVIRONMENT FOR INDUCED EARTHQUAKE IN LONGTAN RESERVOIR OF HONGSHUI RIVER

Pan Jian-xiong

1989, 11(4):  91-99. 

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Based on study in deep geochemisty seismogeology and tectonic stress field, the geological environment in Bayu(Longyu), Bziceng, Moyang and Gengxin of the reservoir district is found in favor of inducing earthquake.