Table of Content

03 June 1981, Volume 3 Issue 2

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Brief Report

EXPERIMENTAL STUDY ON RADON EMANATION OF SATURATED ROCK UNDER ULTRASONIC VIBRATION

Feng Wei, Wang Yongcai, Deng Yuren, Hou Yanzhen

1981, 3(2):  1-7. 

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This paper illustrated experimental study on the influence of ultrasonic vibration upon microstructure and emanation process of saturated rocks. It was found by scanning electron microscope observation that specimens under ultrasonic vibration, whether on the ultrasonically irradiated sides or on the non-ultrasonically irradiated sides, all show a large number of fissured traces, i. e. microcracks. So it can be inferred that under the ultrasonic vibration the development of microcracks provided an outward-diffusing "passage" for the sealed radon to take part in the emanation process.The results of the ultrasonically vibrating experiments indicate that the ultrasonic vibration made the amount of radon separating-out of rock obviously increased, and the amount would be as much as it was before vibration when the vibration stopped. The increment of separating radon depends on the times of ultrasonic vibration. These results obtained are consistent with the scanning electron microscope observation showing that the primary rock structures were certainly destroyed by ultrasonic vibration. During each vibration, new cracks appeared and the separating amount of radon was also increased correspondingly. For the first vibration, the amount of radon increased by a factor of 4.5 under the temperature-control condition (it will be 4.3 under temperature-uncontroi event). For the fourth vibration, it increased by a factor of 9.1 under temperature-control condition (it will be 11.2 under temperature-uncontroi condition). Among the increment of radon, absorbed radon accounts for 64-76 percent, sealed radon accounts for 24-36 percent. The contribution of the ultrasonic thermal effect to the separating radon accounts merely for 10-30 percent.The experiment results show that the rock emanation process was clearly related to the ultrasonic vibration. Its mechanism is rather complicated. It is reasonably considered that prior to the failure of rock the expensive microcracking produced accoustic emission, i. e. ultrasonic vibration, leading to a constant emanation from rocks in a significant amount which may be probably regarded as a precursory information of radon.

REVIEW ON THE APPLICATION OF GROUNDWATER CHANGES IN COMPOSITION TO PREDICT THE EARTHQUAKES OVER THE LAST 12 YEARS

Zhang Wei, E Xiuman, Yang Yurong

1981, 3(2):  8-8. 

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THE SEISMICITY AND THE RECENT CRUSTAL MOVEMENT IN THE HIMALAYA REGION

Ye Hong(Yeh Hung), Zhang Wenyu, Yu Zhishui, Xiu Qin

1981, 3(2):  9-21. 

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In this paper three aspects of analysis are made for the recent crustal movement in the Himalayas on the basis of earthquake data recorded from 1897-1976.1. The characteristics of the present active faults in this region were studied by the fault plane solutions.2. The vectors of the tectonic movement in the lithosphere blocks were calculated by the null vector method.3. The rate of the crustal slip, was estimated from the seismic moment data.In light of the analysis mentioned above, a model of recent crustal movement in the Himalayas is tentatively presented as follows.1. According to the results calculated by the null vector method, the direction of the tectonic movement of the lower lithosphere in the Himalayas is NNE, and its plunge is nearly horizontal, indicating that convergence of the NNE-ward drifting Indian plate and the Eurasian plate was mainly a sort of collision in nature with intensive horizontal compression and shortening rather than underthrusting.2. The regional trend of the western part of the Himalayan arc is nearly perpendicular to the direction of the tectonic movement of the Indian plate. During the process of intensive horizontal shortening of the lithosphere. its upper part upthrusts with a rather low angle over the Ganges Plain, and now the type of movement is still going on chiefly along the main boundary fault and the Ganges Plain boundary fault. The strike of the eastern part of the Himalayas is nearly parallel to the direction of the tectonic movement of the Indian plate. Along this fault belt the Indian plate is moving NNE-ward and has a left-lateral strike slip relative to the Eurasian plate with some upthrust component.3. As a result of the intensive push of the Indian plate applied to the Himalayas, shortening of the latter at a rate of about 3.4 cm/y. was estimated. In the eastern part of the Himalayas the strain energy seems to be released chiefly by earthquake dislocations, but in the western part mainly through aseismic creeps. In the Qinghai-Xizang Plateau north of River Yarlungzangbo, the rate of shortening is probably less than that of the Himalayas. The north-south shortening of this Plateau causes the thickening of the crust and the eastward flow of the crustal materials, and consequently the intensive right-lateral strike slip along the Miju and Red River faults on the south side of this plateau.

DISCUSSION ON PHYSICAL MECHANISM OF THE REGULARITY OF THE NINE DAYS MULTIPLICATION

Guo Zengjian, Qin Baoyan

1981, 3(2):  22-22. 

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CONTINENTAL RIFT VALLEY SYSTEM AND SEISMIC ACTIVITIES IN NORTHEAST CHINA

Zhao Wenfeng

1981, 3(2):  23-29. 

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The Northeast China continent is restricted by the regional stress field, and within it, are developed the NE trending Xialiaohe and Songliao rift valleys. The continental basement is filled with the loose clastic sediments of continental fades, from 1000 up to 5000m in thickness. From the rifts border were ejected lava of olivine basalt and hot water springs, as a result, formed the rings as the earthquake-control zones. The mechanism of the rift valley formation could be viewed as a reflection of the underth-rusting of the Pacific plate.

THE THERMOLUMINESCENCE DATINGS OF BAKED SEDIMENTS IN VOLCANIC LAVA

Li Huhou, Mei Yi, Sun Jianzhong, Ji Fengju

1981, 3(2):  24-24. 

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PRELIMINARY STUDY OF PRINCIPAL FEATURES OF THE NW AND NWW TRENDING FAULT STRUCTURES IN THE YANSHAN REGION

Zheng Binghua, Guo Shunmin, Xu Haomin

1981, 3(2):  25-40. 

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Basing upon the recent field investigations, the principal features of the NW trending fault structure in Yanshan region are summarized in this paper.By analyzing structural, seismological and geophysical data, the authors demonstrated the space distribution, formation, development and movement mode of the NWW trending basement fault zones, as well as their relation to the seismicity. It is suggested that the NWW trending fault zone can be attributed to a crustal fault, controlling both the development of fault block structure and the recent seismicity. The fact that the NW faults spread en echelon and cluster into a zone is a indication of a NWW fault zone in the superficial strata. Moreover, the movement mode of the zone under investigation has a very close relation with the relative motion of the fault block structures. Since Mesozoic and Cenozoic periods, in addition to the differential movement, this fault zone was of shearing motion which had a very obvious changes in nature during the periods from Late Cretaceous to Early Tertiary.

ON THE SEISMOGEOLOGICAL CHARACTERISTICS OF 1976 SONGPAN-PINGWU EARTHQUAKES

Tang Rongchang, Lu Liankang

1981, 3(2):  41-47. 

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This paper discusses the seismogeological background of the Songpan-Pingwu earthquakes, their seismicity, the characteristics of tectonic stress field and the conditions of seismogenic structures in the region under investigation.Judging from the location of epicenters of three strong shocks along the Huya fault, the contour of their synthetic isoseismals and the agreement of fault plane solutions with the occurrence of Huya fault, the authors come to a preliminary conclusion that the studied events were caused by the dip-slip displacement of NNW trending Huya fault with a slightly sinistral component and under the action of nearly EW trending tectonic stress field.

NEW EVIDENCES OF THE EARLY ORDOVICIAN LITHOFACIES AND BIOFACIES CHANGES IN LINAN AND YUHANG COUNTIES, ZHEJIANG PROVINCE

1981, 3(2):  48-48. 

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TECTONIC CONDITIONS OF OCCURRENCE OF STRONG EARTHQUAKES IN SHANDONG PROVINCE

Gao Weiming, Li Jialing, Sun Zhuyou

1981, 3(2):  49-56. 

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From the analysis of the distribution of strong earthquakes, the deep-seated crustal structures and the medium conditions, the authors of this paper attempt to divide the faults within the earth's crust into six groups and to estimate the depth and characteristics of seismo-pregnant layers. The motion of upper mantle materials, the faulting and seismicity are a common source-contemporaneous. The occurrence of strong earthquakes is directly controlled by the activities of both deeply penetrating faults and faults of basaltic layers.

SOME FEATURES OF CONTEMPORANEOUS FAULTS IN BEIJING PLAIN AND THEIR SIGNIFICANCE

Peng Yimin, Li Dingrong, Xie Zhenzhao, Wang Ande, Liu Qingsi

1981, 3(2):  57-64. 

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By the data obtained- from the seismogeological work in the Beijing plain, the authors supposed that all the main active faults in this region were of contemporaneous nature and originated at the same time as the deposition took place. In our opinion, the study of contemporaneous faults is of great significance. At the end of this paper a general morphological model for contemporaneous faults is presented.

ON NEOTECTONICS OF THE HUNHE FAULT ZONE

He Chisong

1981, 3(2):  65-68. 

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The Hunhe fault zone is a western extension of the Shenyang-Dunhua Mishan fault and there can be found an evidence of Pre-Sinian movement. It is suggested that the faulting of Hunhe fault zone was significant in Mesozoic time and more intensive and frequent in Tertiary and Quaternary.Basing upon the data on geology, morphology and seismicity. this paper illustrates the trace of the neotectonic movement since Tertiary.Actually this fault acts as one of main faults of Cathaysian tectonic system. In general, this paper deals with only the Shenyan-Qingyuan section.

THE HYDROGEOCHEMICAL CHARACTERISTICS AND PRECURSORY INDICATORS IN THE COASTAI REGION, FUJIAN PROVINCE

Cai Shihuang, Yu Zhaokang, Lin Jiatao

1981, 3(2):  81-82. 

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OUTCOME OF "THE SEISMOTECTONIC MAP OF ASIA AND EUROPE"

Chun Zhu

1981, 3(2):  83-83. 

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