Table of Content

01 December 1986, Volume 8 Issue 4

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Brief Report

INDUCED SEISMICITY AT HUNANZHEN RESERVOIR,ZHEJIANG PROVINCE

Hu Yuliang, Chen Xiancheng, Zhang Zhonglian, Ma Wentao, Liu Zuyuang, Lei Jun

1986, 8(4):  1-25. 

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Hunanzhen reservoir with a dam 129m high and a volume of 2?10⁹m³ is located in Quxian County,Zhejiang Province.A series of tremors have occurred since its impoundment in 1979.A dense seismic network was installed in the epicentral area during high water season of 1982 and 1983.Hypocenters of 1029 were located and focal mechanism for 372 events was individually determined.The observations show that almost all of the events are clustered along the immediate banks upstream 15km from the dam and have quite shallow depth only of hundreds of meters.Seismic activities bursted with rapid fluctuation of lake level only in hours to days'delay.Focal mechanisms demonstrate that most are of thrust fault and next the normal.Analysis of the data suggests that the seismicity is caused by the slips along the preexisting fractures due to the water seeping under the effect of local stress in the banks or the gravitation of rock mass.Future seismic activity is expected to be continued for a time but to be limited in magnitude.

ONE-DIMENSIONAL INVERSION FOR THE DATA ON MAGNETOTELLURIC PHASES

1986, 8(4):  26-26. 

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ANALYSIS OF STRESS FIELD ON FAULT ON LIAODONG PENINSULA AFTER HAICHENG EARTHQUAKE

Song Huizhen, Sun Junxiu, Liu Lihua

1986, 8(4):  27-49. 

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From the information oi active faults and focal mechanism the behaviour of fault zones is described plastically according to the increment concept.The stress field of the fault in relation to fault geometry and regional stress field is estimated numerically by using nonlinear finite element method.The Coulomb-Navier theory is used as criteria for failure of element in fault zones.For some elements'stresses are released with each time incremental step.Thus,a process of variation and adjustment of stress (ield of the fault can be simulated and the potential stress release area can also be determined on the basis of stress pattern of element.Combining the ratio of the radius of stress circle of future stress release area to that of the largest historical stress release area with the ratio of the volume of the future stress release area to that of the largest historical stress release area,we can estimate intensity of future stress release.

SUPPLEMENT OF THE PALEOEARTHQUAKES FOR SHANGFANGSHAN IN THE FANGSHAN COUNTY

Wang Tingmei, Li Jianping

1986, 8(4):  50-50. 

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ACTIVE FAULTS AND THEIR RELATIONSHIP WITH SEISMIC ACTIVITIES IN DALI OF YUNNAN PROVINCE AND ITS ADJACENT REGIONS

Li Xianggen, Ran Yonkang, Peng Gui, Zhang Jing, Quo Shunmin, Xiang Hongfa, Chen Tieniu, Zhang Guowei, Ji Fengju, Ye Yongying

1986, 8(4):  51-61. 

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Geological evidence indicates that the fault activity on the middle segment (Dali and its adjacent region) is the strongest along the Honghe fault (the Red River Fault).The active fault shows a distinct tendency of getting younger from the ends to the middle segment of the fault,i.e,faulting in the Dali area is the youngest,which coincides with the distribution of recent strong shocks.Geological evidence and its ages show that five events with a recurrence interval 昽f about 1500 years occurred in the middle-late Holocene time,presumably associated with an earthquake of M=8.

SCIETIFIC MEETING FOR TWENTIETH ANNIVERSARY OF XINGTAI EARTHQUAKE IN SHIJIAZHUANG

Yao Yanzhi

1986, 8(4):  62-62. 

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TWO KINDS OF CHARACTERIZED MYLONITES AND THEIR GENESIS AND GEOLOGIC SIGNIFICANCE

Sun Yan, Shen Xiuzi, Xuang Zhongzin, Jia Dong

1986, 8(4):  63-69. 

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On the basis of systematical observation on mylonites in hundred of fault zones or more in eastern China and with referring to different divisional views of some researchers for mylonites categories,authors have stressed such three factors on which classification of mylonites depends as the texture,the mechanical genesis and the physical character of fault rocks.Obviously,mylonites which may be included in ductile deformation are based upon the characters of physics and mechanics.Actually,these mylonites may be also divided into three categories,shallow,low temperature and brittle deformation mylonite,i.e.B type;moderate-high temperature and ductile mylonite,i.e.D type;deep,high temperature viscous mylonite i.e.V type.As mentioned above,each category of the mylonite shows the different typical character.B type (brittle-tracture type) is of mylonitic texture,the D type (ductile-gliding type),of subgrain structure,and the V Type (viscous-flow type),of flow structure.These properties are correlative and may have a transition each other as well.In the studied categories,authors mainly describe and compare the B and D types of the mylonite.

INTRODUCTION OF SIXTH INTERNATIONAL CONFERENCE OF GEOCHRONOLOGY,COSMOCHRONOLOGY AND ISOTOPE GEOLOGY (ICOG VI)

Chen Wenji

1986, 8(4):  70-70. 

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INVESTIGATION OF EPICENTRE OF JINZHOU M=6.0 EARTHQUAKE OF 1861

Zhong Yizhang, Wang Ligong, Zhu Haizhi

1986, 8(4):  71-75. 

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The southern Liaoning Province is one of the strongest seismic zones in Northeast China,where have happened a series of destructive earthquakes.The epicentre of Jinzhou earthquakes of magnitude of 6.0 that occurred in 1861 was the Jinzhou in previous documents.However,based on field investigation.and available data,the epicentre in point should be located adjacent to the Huitun in the Xinjon County,about 42 km far from the Jinzhou to the southwest.

SYMPOSIUM ON THE PREDICTION OF EARTHQUAKE HELD IN WEST BERLIN IN 1986

Wang Ruobai

1986, 8(4):  76-76. 

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EFFECT OF PLASTIC COMPONENTS IN ROCKS ON THE MODES OF INSTABILITY

Wang Shengzu, Shi Liangqi, Zhang Liu

1986, 8(4):  77-84. 

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As welll known,the instability modes of rocks depend on quite a number of factors,such as rock type,fault gouge,temperature,confining pressure,strain rate and liquid media,etc.It is emphasized in the paper that all of them are associated with the plastic components contained in rocks to different extent.The plastic components of rocks are referred to those of minerals which can deform irreversibly under the given geological and physical environment.Triaxial compression tests of intact quartzite,granite,granodiorite,gabbro and basalt under room temperature and confining pressures up to 0.7 GPa indicate that the contents of plastic components in rocks have no obvious effect on the magnitudes of stress drop of sudden instability,but do influence the instability modes.The plastic components filled in the elastic framework of rock affect the elastic behavior of rock specimen on the whole in two aspects: (1)The effective bearing area of specimen and the effective height of reversible deformation part in specimen are reduced and higher stress level is necessary to accumulate enough reversible strain energy for sudden instability; (2) The plastic components,as damping elements,hinder the rebound of elastic framework and higher strain energy is necessary too.

ON PORE PRESSURE PARAMETER IN SATURATED ROCK-SOILS

Che Yongtai

1986, 8(4):  85-90. 

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The parameter is used to explain the relationship between pore over pressure and stress in saturated rock-soils under triaxial compression.This is an important subject in the studies of anomalous mechanism of underground water level in a well before an earthquake.In this paper,on the basis of results from laboratory and field test,and of some date of observation in a well,the influences of rock or soil characteristics and loading rate upon the parameter have been researched.

QUANTITATIVE ANALYSES ON THE CALIBRATIONS OF THE INDUCTION MAGNETOMETER

Deng Qianhui

1986, 8(4):  91-98. 

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The best way of calibrating the induction magnetometer is presented and this paper deals with such aspects in quantitative analyses as: selection of calibrating,optimization of calibrating the coils and calibration error,and so onThis research can provide some useful references to coiling,field work in this regard and improvement of the calibration precision.