Table of Content

09 March 1994, Volume 16 Issue 1

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Brief Report

THE CRUSTAL DEFORMATION FIELD AND IT'S DYNAMIC FEATURES IN BEIJING AREA

Wang Ruobai, Yang Guohua, Geng Shichang, Sun Dongping

1994, 16(1):  1-9. 

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Theprecise Ieveling data for several perid in Beijing area have been adjusted by using samecalculated method for uniform leveling network and from the same initial point.The maps of vertical crustal deformation rate from 60＇s to 90＇s have been drown on microcomputer using curvefiting method. The features of crustal deformation,including its long-term tendency and featuresfor each seismic episod during more than 30 years have been also systematically studied in Beijingarea.These results offer some important clue to both seismic prediction study and the theoreticaldeformation field.

A PRELIMINARY STUDY ON A PALEOEARTHQUAKE FISSURE IN LINTONG, SHAANXI

Zhang Anling, Hu Wei, Mi Fengshou, Wu Jianfang

1994, 16(1):  10-11. 

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DISCUSSION ON SLIP MODE OF F₁ IN NORTHERN SEGMENT OF THE YISHU ACTIVE FAULT

Yang Yichong, Gao Weiming

1994, 16(1):  12-20. 

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Based on field investigation and laboratory analysis,we discussed the slip mode of F₁ in thenorthern segment of the Yishu active fault in this paper. The macroscopic identification and analysis of the composition of clay minerals of fault gouge shows that it slowly sliped with the mode of creeping before late Pleistorene,while micro features indicate that it strongly stick-sliped before Pleistocene.Along with the study of chronology,it is preliminarily interpreted as variousstages from sticking-slipping slide to creep.This result is of practical significance to earthquakeprediction and engineering construction in the area nearby the Yishu fault zone.

STUDY ON THE JUMPING─OVER RELATION BETWEEN EARTHQUAKE AND MAGNETIC STORM

Xu Daoyi, Wang Xiangnan, Shen Zongpi

1994, 16(1):  21-25. 

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Thejumping-over relations between magnetic storms,between magnetic storm and lunarphase,between magnetic storm and great earthquake,and also between great earthquakes havebeen investigated,which show some correlation to the variations of relative positions of Sun,Mcon and Earth. Significant orderliness has been found based on the jumping－over relation between the magnetic storm that occurred on Nov. 30,1988,and several subsequent occurring magnetic storms and great earthquakes.Most of time intervals may be obtained as the results of synodic month or nodical month periods multiplied by factors,which are such prime numbers as 19,23,29,and 31.It seems that there is a close relation between earthquakes and several magneticstorms.

¹⁴C DATING OF DESERT SOIL FROM THE DUSHANZI AREA AND ITS SIGNIFICANCE

Peng Gui, Jiao Wenqiang, Zhang Jialin, Li Guiying, Gao Songsheng

1994, 16(1):  26-28. 

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Discussed here is the source of carbon in tbecarbonate sediments as well as the reliability of their ¹⁴Cdating,It is significant to determine the soil age on the basis of the inorganic carbon in soils.

DISTRIBUTION OF EARTHQUAKES, STRESS STATE AND INTERACTION OF THE PLATES IN THE SOUTHERN TAIWAN─PHILIPPINES AREA

Zhang Shaoxian, Chen Qizhi, Huan Jinshui

1994, 16(1):  29-37. 

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Abstract The spatial distribution of m_b≥5.0 earthquakes and their focal mechanis solutions havebeen studied for the southern Taiwan─philippines area by use of ISC seismic data,as well as thepatterns of the subduction zone and the stress state in the crust and subduction zone along withthe other resuIts from the geophysical studies.It is considered that the eastern boundarv of theSouth China Sea plate consists of such subduction zones as southwestern Taiwan,Manila,Negrosand Cotabato.The western boundarv of the Philippines plate consists of the subduction zones ofEast Lazon trough and Plilippine Sea.The Philippine Islands are a transitional zone of being deformed.In the presence of that transitional zone,the South China Sea subplate has subducted beneath the Philippine Islands and the Philippine plate has a weak effect on the southern part.Key works：Subduction zone,Stress field,Plate movement,Focal mechanism solution,Taiwan,Philippines

SEISMOLOGICAL STUDY FOR WEIHAI CITY

Cai Keming

1994, 16(1):  38-42. 

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Weihai City lies on the eastern end of Shandong Peninsula;a part of the famous fault zone(Zhang Jiakou-Bohai-Weihai)goes across the city,where there occurred destructive earthquakes many times.This paper gives some data of seismology,hydrology and engineering geology and preliminary discussion andanalysis of the fault zone in question has been carried out.The author has come to a conclusion that the activityis in evidence.

IS THERE VOLCANIC ACTIVITY IN HUNAN PROVINCE?

1994, 16(1):  42-42. 

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A COMPARATIVE STUDY OF MAIN ACTIVE FAULT ZONES ALONG THE COAST OF SOUTH CHINA

Zhang Hunan, Wu Qianhong

1994, 16(1):  43-52. 

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Developed along the coast of South China have been three sets of active fault zones,in whichthe NE～NNE trending faults are of the largest scale,with their surficial manifestation most evident and with the ENE～EW trending faults cutting most deeply and the developing historylongest,as well as with their growth and activity most evident for the NW～WNW trendingfaults.The resuhlt indicates that the characteristics of all faults mentioned above are in evidence inmacro～microtectonics,suggesting that the faults are of similar formations and developing history and controled by similar sources of tectonic forces.Their characteristics are to some extentrepresentative of the evolutions of the crustal motion.

EXPERIMENTAL STUDY OFTHE INFLUNENCE OF PORE PRESSURE VARIATION ON SLIDING BEHAVIOR OF ROCK SURFACES

Li jianguo, Song Ruiqing, He Changrong, Wang Shengzu, Zhang Liu

1994, 16(1):  53-59. 

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In order to understand relation between earthquake activity and the variation of pore pressure,this work studied the effect of pore pressure rate on the sliding behavior between rock surfaces,with constant normal stresses ranging from 10 to 120MPa. The result shows that,withhigh increasing rate of pore pressure,surfaces with low increasing rate of pore pressure,slidingbehavior was characterized by stable sliding,and there occurred a transition between the twomodes with a moderate increasing rate. The above mentioned result is important in future research on the precursory phenomena ofearthquake and earthquake control.

THREE-DIMENSIONAL FINITE ELEMENT MODEL OF VARIABLE VISCOSITY, FLOW IN THE MANTLE

Zhang Shuxia, Luo Huanyan

1994, 16(1):  60-70. 

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Athree-dimensional finite element model has been constructed for tbe variable viscosity,compressible Netwonian flow in the mantle.In development of the formulations,the motion equation starts from the momentum equation which is described in terms of stress components.The physical properties of the mantle,such as rheology,equation of state,the thermal conductivity and others are of three-dimensional heterogeneities,they can be evaluated either using theempiric formula or the laboratory experiments depending on the problem to be studied.As an example,a medel with variable viscosity and no slip at bottom is shown for the typical three-dimensional flow pattemrn.

CHARACTERISTICS AND IMPLICATIONS OF ACOUSTIC EMISSION ENERGY IN THE PROCESS OF DEFORMATION AND FAILURE OF SINGLE-JOINT ROCKMASS

Zeng Zhengwen, Ma Jin, Wu Xiuquan, Wang Aifang

1994, 16(1):  71-77. 

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Rockmass models with single-joint cemented by plaster were compressed uniaxially.Fullwaveforms of acoustic emission(AE)events were recorded. Relative AE energy was calculatedwith the full waveforms.Analyses of the results show that AE energy are closely related to theprocess of deformation and failure.Distribution of AE energy reflects the scatter of fracture dimensions,the larger the AE energy,the bigger the fracture dimension.The fracture modes arernainly controlled by the joint angle(θ)and Poisson's ratio(ν)of the plaster.When θν)/ν),mode-Ⅱ(shear)is the major fracture form and AE energy concentrates onrelatively fewer events.When θ＞arctg(0.707·(1-ν)/ν),mede-Ⅰ(extension)is the major fracture form and AE energy scatters on more events.The results suggest that rockmasses with dif-ferent structures have different modes in deformation and fracture,and would be different in precursory modes and warning time of failure.

DISCCUSION ON "9.5" KEY SCIENTIFIC STUDY OF UNDERGROUND FLUID BRANCH

Che Yongtai

1994, 16(1):  79-82. 

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THE PHYSOCAL AND MECHANICAL PROPERTIES OF CHLORITE-SCHIST AND PLAGIOCHASE AMPHIBOLITE AT HIGH P T CONDITIONS AND ITS APPLICATION

Gao Ping, Liu Ruoxin, Ma Baoling, Li Biao, Mu Runchang

1994, 16(1):  83-88. 

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The conductivity,P-wave velocity and the strengh of chlorite-schist and plagiochase amphi-bolite were measured at high P T conditions.It has been shown that the dehydration of water-bearing minerals wolild lend to abnormal changes of physical and mechanical properties.The dehydrating temperature decreased with increasing pressure at semi-sealed condition. It has beenpresented that the dehydration of water-bearing minerals in chlorite-schist and plagichase amphi-bolite should be the cause of the low-velocity/high conductivity layer(or body)in North Chinacrust,This layer(body)should also be a soft layer(body)with low strgngth,favourable to theoccurrence of earthquake.

CHAKACTERISTICS OF ILLITE MINERALS IN FAULT GOUGE FROM XIAOWAN, YUNNAN AND THEIR GEOLOGICAL SIGNFICANCE

Zhang Bingliang, Liu Guifen, Fang Zhongjing

1994, 16(1):  89-96. 

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In this paper,characteristics of illite in fault gouges are studied by SEM, XRD and chemicalanalysis.The study shows that illite belongs to I ＋ISIl structure;expansibility takes approximately 15%; IMis of multiple paterns interlayer positive ions 2Ca＋Na＋K≈l;b₀ value of illite is 8.993Å in fault gouge at Xiaowan,which show that mechanisms of fault movement in Xiaowanare of low pressure and temperature(<200℃)。