Table of Content

04 June 1986, Volume 8 Issue 2

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Brief Report

THE B-VALUE OF ACOUSTIC EMISSION FOR THE SAMPLE WITH "λ"-PATTERN CRACKS AND THE PHYSICAL SIGNIFICANCE OF THE FREQUENCY-MAGNITUDE RELATION

Du Yijun, Ma Jin

1986, 8(2):  1-20. 

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In this paper,the b-value of acoustic emission for the sample with "λ"-pattern cracks and the physical significance of the frequency-magnitude relation were experimentally and theoretically studied.The geometry of μλπ-pattern cracks influences the b-vnlue,and the b-value is very low.There are two kinds of processes of the b-value as a function of loading:one is that b decreases continuously and keeps low as loading level increases;the other is that b decreases and then rises or rises undulately.The change of b-value probably is closely related to the microfracturing processes.According to the physical picture of origination,propagation and coalescence of mierofractures,the distribution equation of microfractures was established.In the case without the interaction of cracks,the solution of the distribution equation is the Gutenberg and Richter relation.In the case of crack interaction,the solution of the distribution is not a simple power function,the frequency-magnitude relation deviates from linearity in logarithmic coordinates and it may be a precursor of large earthquakes.

SOME SEM MICROTEXTURES OF QUARTZITE FROM STICK-SLIP AND STEADY STATE SLIP EXPERIMENTS AND THEIR SEISMOGEOLOGICAL SIGNIFICANCE

Yang Zhuen, Zhang Liu, Shi Guimei

1986, 8(2):  21-25. 

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Some Scanning Electron Microscopy (SEM) microtextures have been observed on the products of quartzite from triaxial compression experiments with a confining pressure of 1-5 Kb and a strain rate of 4.4?10^-5/sec.The SEM microtextures resulting from stick-slip are distinguishable from those resulting from steady-state slip.The former shows the characteristics of bashing and shearing fracture or rapid slipping,and the latter demonstrates those associated with rubbing fracture and slow shearing.The SEM mic-rotextures in products from active faults can be compared with those from experiments.It is significant to distinguish between stick-slip and steady-state slip motion of active iaults by using these typical SEM microtextures.

EXPERIMENTAL STUDY ON THE MEASUREMENT CONDITION FOR QUICK THERMAL CONDUCTIVITY METER

Zhang Ruhui, Xie Yizhen, Li Xingrong

1986, 8(2):  26-32. 

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This paper is to deal with the measurement condition for the QTM meter used in the experiment and its reliability.With the comparison of the experimental data the meter in question,has proved to be the same in its performance as the stable plate thermal conductivity meter,an error within 10% for the isotropic samples and within 5% for the rock sample.

THE VELOCITY OF HOLOCENE VERTICAL TECTONIC MOTION IN THE COASTAL AREA OF FUJ1AN AND GUANGDONG

Chen Weiguang, Zhang Hunan, Li Ziquan

1986, 8(2):  33-42. 

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The tectonic motion in South China is characteristic of vertical uplifting and subsiding of the blocks.Based on the data for such 58 Holocene carbonaceous samples from the study region as shells,beach rock,puddle,peat and coral reef,the authors estimated and compared the rate of the vertical tectonic motion for various fault block regions,which have been confirmed by the rate of the present crust deformation.The results indicate that the motion of the active fault has a rate of 1.5mm per year while the inactive,only about 0.5mm per year.The former is of a value 3 or 4 times the latter and forms the part of main seismic zones in the study region such as the Quanzhou-Santou seismic zone and those in the northern Hainan Island.And the inactive fault blocks make up the nonseismic zones or the microseismic region such as the southern Hainan Island and the Zhujiang Delta.The value in point corresponds with the strength of the seismicity.In this paper the authors discuss the relationship between the differential velocity for the moving blocks and the neotectonic stress field along the coastal area of South China and indicate that because the crust of southern Fujian and the eastern Guangdong are in the process of being deformed between Pacific plate and Phillippine Sea plate,the strength of the tectonic motion is more intensive than the central Guangdong and may act as a seismic barrier to the latter.In the coastal area of western Guangdong the crust is in the presense of the tension of South China Sea basin,the strength of tectonic motion being also larger than the central Guangdong.The velocity of vertical tectonic motion in the coastal area of South China gradually increases from the central Guangdong to the southern Fujian and eastern Guangdong and from the central Guangdong to the eastern Guangxi and western Guangdong.The vertical differential movement of the blocks is only a main model in the coastal area of South China and its adjacent area.

GRAVITY MEASUREMENTS AND THEIR TECTONIC IMPLICATION IN EAST CHINA SEA AND ADJACENT REGIONS

Xi Jusheng, Liu Suowang, Zhu Zhongfen, Liu Guangquan

1986, 8(2):  43-52. 

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The measuring accuracy of the ZYZY-type Sea Gravity Meter,developed by Seis-mological Institute of State Seismological Bureau,was re-determined by sea gravity data that had been obtained during 1977-1979 in the study regions.The basic contours of free-air gravity anomalies,Bouguer anomalies and crustal thickness etc.were compiled.The characteristics of the crustal structures for the region in question were investigated with reference to geological and geophysical data.

CHARACTERISTICS AND MECHANISMS IN RECORDED EARTHQUAKES BY THE LEVEL FLUCTUATIONS IN LOG YU 38

Jing Zhiguo

1986, 8(2):  53-60. 

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A lot of worldwide earthquakes are represented by the level fluctuations in Log Yu 38.This paper is to discuss the characteristics and the mechanism oi the earth-quakes.This well along with the ambient aquifer system means a sensitive volumetric strain-meter to the earthquakes,and to the crustal deformation as well.Its ability of recording the shocks is believed to be closely relative to the hydrogeological conditions of the aquifer system and its texture.

VERTICAL CRUSTAL DEFORMATION AND VARIATION OF GRAVITY FIELD AND RECENT CRUSTAL MOVEMENT IN THE TANGYIN GRABEN AND ADJACENT REGION

Zhao Jiangzhen, Gu Menglin, Liu Jianhua, Lu Guohe, Zhang Xiangro

1986, 8(2):  61-67. 

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The northern part of the Henan Province has been being one of main seismic monitoring regions in North China.Therefore,the networks of the vertical crustal deformation and the portable measurement of gravity have been established in the study region.The study of recent crustal movement has been made as well.Based on the date obtained the authors discovered the data are very coincident for three parts of the work,the results of crustal deformation and gravity mesurement showing the recent crustal movement in the study region which may be taken a sa diastro-phic background of the potential seismic activity for the moniroring region in the He-nan Province.

HOT SPRINGS HAVE BEEN DISCOVERED FOR THE FIRST TIME IN THE LIYANG AREA JIANG SU PROVINCE

Zhong Huabang

1986, 8(2):  68-68. 

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EXPERIMENTAL RESEARCH OF ROCK FRACTURE UNDER PORE-TRIAXIAL STRESS CONDITION

Wu Jingnang, Wu Mianba

1986, 8(2):  69-76. 

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In this paper fracturing behavior of granite and marble as well as the effect of the stress path on the rock fracturing strength,is studied by use of the rock pore-triaxial apparatus.The test results show that:(1)strength of pore-pressure fractured rock increases with increase of confining,pressure;(2)under the tensile-compressive stress the rock shows the tensile fracture and the tensile stress which causes fracture in the rock decreases with increase of the axial pressure;(3)the values of rock tension strength from hydrofracturing are higher than those from other methods.

FAULT DISPLACEMENT AND RECURRENCE INTERVAIS OF EARTHQUAKES ON THE NORTHERN SEGMENT THE HONCHE RIVER FAULT ZONE,YUNNAN PROVINCE

Guo Shunmin, Zhang Jing, Li Xianggen, Xiang Hongfa, Chan Tieniu, Zhang Guowei

1986, 8(2):  77-90. 

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Displacement rale along the Honghe River fault (northern segment) since Pleistocene was determined in this paper on the basis of geological investigation:for the narrow valley segment (Dingxiling),offset rate is 8mm/yr,and the throw rate is 1.8mm/yr;for wide one (Dali),5mm/yr and 9mm/yr,respectively.It can be estimated from the parameters of fault displacement that recurrence intervals for M6,8 earthquake are 178?29 years.It is consistent with the recurrence intervals (150?50 years) of M 6-7 earthquakes from historic seismic records in this area.It may be useful to immediate-long term earthquake prediction.

THE ACTIVITY OF A FAULT ZONE INFERRED FROM MICROSTRUCTURAL STUDY OF DEFORMED ROCKS

He Yongnian, Lin Chuanyong, Shi Lanbin

1986, 8(2):  91-96. 

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The neotectonic activity of a minor fault zone on the Southwest margin of Yangzi platform has been studied based on analysis and comparison of the microstructural features of deformed rocks within and outside the fault zone.According to thermoluminesccne dating it is proposed that after Pleistocene there would be more than one active period of the fault.The strees of the main period was up to 700 bars.The strain and stress of the rocks within the fault during the faulting process were significantly greater than those in the rocks outside the fault.

TRACE OF THE ANCIENT EARTHQUAKES FOUND IN THE HEIZI RESERVOIR IN XINJIANG

1986, 8(2):  97-97. 

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