Table of Content

09 September 1992, Volume 14 Issue 3

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Brief Report

KINEMATIC FEATURES OF TECTONIC DEFORMATION OF TERRANES IN THE XIZANG (TIBETAN) TETHYAN BELT

Shen Xianjie

1992, 14(3):  193-215. 

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From the point of view of plate kinematics a unified convergence velocity model is employed to derive a series of kinematic equations for deformation of Himalaya and Lhasa-Gangdise terranes during the Himalayan orogeny.These equations describe terrane shortening,crust-upper mantle thickening,lateral strike-slip movement,plateau surface uplift,erosion planation and isostatic height of the crust,etc.These kinematic equations for terrane deformation derived on the basis of mass conservation define the macroscopic trends of tectonic evolution of 2-D deformation of the Himalaya Terrane and 3 D deformation of the Lhasa-Gangdise Terrane during the 40Ma of the Indian-Eurasian convergence-collision on the one hand,and provide the systematically defined initial and boundary conditions for further study on the process of tectono-thermal evolution of the deformed terranes on the other hand.

THE DISLOCATED HOLOCENE ALLUVIAL-DILUVIAL FANS RELATED TO THE ACTIVITY OF THE JIAOCHENG FAULT IN SHANXI PROVINCE

Jiang Wali, Nie Zongsheng, Zhang Kangfu

1992, 14(3):  216-216. 

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ANALYSIS OF SEISMOGENIC CONDITIONS IN THE WEDGE TECTONIC REGION OF SOUTHEAST YUNNAN PROVINCE

He Honglin, Li Ping, Fang Zhongjing

1992, 14(3):  217-226. 

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The wedge tectonic region,in which there are complex features of fault geometry and strong seismicity,is a special tectonic location.This location is a interlock region of the Honghe fault zone and Xiaojiang fault zone in southeastern Yunnan Province.First,a detailed discussion is griven geometric characteristics of main active faults in wedge tectonic region:Qujiang fault and Lihaozhai fault interlock in Qujiang basin in the shape of "┤",the former is confined at the western side of the later;Jian-shui pull-apart area is formed by right-lateral range of Lihaozhai fault and Jianshui fault,in which the former interlocks with Yilonghu fault in Jianshui basin and Heinidi fault is confined at the eastern side of the later.Jianshui fault is replaced gradely by fragment breccia zone on southern segment,ending at Shanhua on the northern side of Honghe fault.These faults are confined on the northern side of Honghe fault zone which is the dividing line of first class tectonic unit.Second,after the analysis of the types of deformation combination,the block movement model has been established,and the dynamic mechanism of this model has been explained.Finally,the analysis of the relationship between fault-block movement and seis-misity has been made.

TENTATIVE ANALYSIS OF SLIP PATTERNS AND SEGMENT TYPES OF ACTIVE FAULTS

Ran Yongkang, Wang Yipeng, Fang Zhongjing

1992, 14(3):  227-236. 

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This paper deals with the slip patterns along active faults and their segment types from the data of ruptures by historic earthquakes,palaeoearthquakes and time of fault movement.Some cases show that there are at least 8 patterns of fault slip and relevant segments.These segments can be merged into 4 main types-stable,transient,variable and shrinking segments according to fault slip characters.And we can also define these segments to be of typical characteristic-earthquake type,extensive characteristic-earthquake type and non-characteristic-earthquake type.The stable segment is the most important and general one of the 4 types of active fault segments.There is some difference in the earthquake mode and magnitude between these types of segments.

GRADIENTS OF VERTICAL DEFORMATION RATES AND HIGH-RISK AREAS OF STRONG EARTHQUAKE IN CHINA

Zhang Yingzhen, Zhang Liren, Su Shengping, Li Zhixiong

1992, 14(3):  237-244. 

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In this paper,we introduce a method which can be used to determine the gradient of vertical deformation rates and discuss the relation between the gradients of deformation rates and tectonic and seismic activities.Using the digital results from the map of present-day vertical deformation rates in China,we draw a contour diagram of the horizontal gradients of vertical deformation rates in China.A comparison between the zones with high gradient of deformation rates and the locations of strong earthquakes is made and the possible high-risk areas of strong earthquakes in the coming twenty years are also pointed out.

RESULT OF HARMONIC ANALYSIS OF EFFECT OF EARTH TIDE ON WATER LEVEL IN SEVEN WELLS IN NINGXIA AND ITS APPLICATION

Wang Yong

1992, 14(3):  245-250. 

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The effect of earth tide on water level in seven wells of the Ningxia well network is systematically studied.Tide parameters of main tide wave effecting on the water level in seven wells are given after harmonic analysis.From the tide parameters some physico-mechanical parameters of aquifer in seven wells are obtained.The ability of well-aquifer system to reflect the crustal stress and strain and using the effect of tide on well water level to study earthquake prediction are discussed.

GEOCHEMICAL CHARACTERISTICS OF GASES IN WUDALIANCHI VOLCANIC AREA OF HEILONGJIANG PROVINCE

Gao Qingwu

1992, 14(3):  251-258. 

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A systematical study of geochemical characteristics of gases in Wudalianchi volcanic area leads us to find that the main component of the gases is CO₂ and minor components are rare gas He,microgas H₂ and radioactive gas Rn.The gases are characteristic of post eruption volcanic gases.In plane distribution,CO₂ ejects in Laoheishan and Huoshaoshan latest eruption activity zone and tectionic activity area.The formation conditions and origin of CO₂ are analysed,and release amount of CO₂ is also roughly estimated.From February to April,1988,H₂ in the South Spring exhibits large-amplitude positive anomaly variation.We think it has ralation with nearby small earthquake cluster.The discover and study of a gas hole in ice cave at Laoheishan volcanic crater is important for monitoring and studying future volcanic activity.The gas from the volcanic gas hole is a mixed gas composed of He,H₂ and CO₂.We think this volcanic gas hole is related with deep structure and lalest volcanic eruption.

CHARACTERISTICS OF SEISMIC-SOURCE FAULTS WITHIN THE CONTINENTAL PLATE

Gao Xianglin, Luo Huanyan

1992, 14(3):  259-264. 

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On the basis of analysis of the continental seismotectonics a relationship between shallow earthquakes and faults is discussed.It is now widely accepted that earthquakes are caused by dynamic spreading of shear rupture zone on a discontinuous plane which is called source fault.Seismic-source faults within the continental plate are characterized by complicated regional variation in styles which depend on the tectonic setting and the geodynamic processes.Two types of seismic-source faults within the continental plate have been suggested:(1) Seismic-source fault of type A is usually consistent with the active tectonic fault existing on the ground and represents a bound ary between tectonic blocks;(2) Seismic-source fault of type B is buried in the crust and determined only by fault plane solutions of earthquakes.It has been found that the movement pattern along the seismic-source faults of type B is different from the mapped active faults on the surface in the extentional regions.Accordingly it is necessary to use different methods for research of the seismic-source faults of the two types.

CHARACTERISTICS OF FAULT GOUGE FROM THE NW-TRENDING FAULTS IN WEST SHANDONG AND ITS SEISMO-GEOLOGICAL IMPLICATIONS

Wang Hualin, Chao Hongtai, Geng Jie

1992, 14(3):  265-273. 

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A systematic study is made on the characteristics of fault gouge from NW-trending faults in West Shandong.The macro-structural features of the fault gauge zones have been investigated.Based on the surface textures of quartz grains from the gouge and its maturity,the relative age,the movement pattern,rupture mode and activities of the NW-trending faults are determined.In addition,its seismo-geological implications and some problems in studying fault gouge are discussed.

HISTRIC RECORD OF EARTHQUAKES IN TAIWAN

Liu Zhaomin

1992, 14(3):  274-274. 

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DETERMINATION OF POTENTIAL EARTHQUAKE SOURCE FROM BOTH SEISMIC AND GEOLOGICAL DATA

Zhang Yuming

1992, 14(3):  275-278. 

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This paper summarizes seismic and geological data used in determining potential earthquake source for compiling Seismic Zoning Map of China(1990),including determination of the extent,direction and upper-limit magnitude of potential earthquake source,as well as the upper-limit magnitude of background earthquake.

SURFACE RUPTURE HAZARD ANALYSIS OF A SITE

Yu Ketao, Jiang Pu, Luo Huanyan

1992, 14(3):  279-285. 

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Fault rupture is a main type of earthquake-induced geological hazards in the region where faults are developed.Generally speaking,the damage to structures caused by surface rupture is difficultly to withstood.Therefore,Rupture hazard analysis becomes a more important subject in earthquake microzonation.Based on the principles of seismic risk analysis,the paper presents a rupture hazard analysis model for a site with the at-enuation of displacement taken into account Finally,taking the Xianshuihe fault as an texample,we make an estimation of the rupture hazard of a certain site.

STUDY OF GAS SAMPLING CONTAINER AND FIELD SAMPLING METHOD

Kong Lingchang

1992, 14(3):  286-288. 

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SEISMICITY EMERGING IN THE RESERVOIR AREA OF TONGJIEZHI HYDROELECTIC STATION,SICHUAN PROVINCE

Lu Guixuan

1992, 14(3):  288-288. 

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