Table of Content

04 December 1996, Volume 18 Issue 4

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Brief Report

LATE QUATERNARY SEGMENTATION AND SEGMETED VARIATIONS IN TECTONIC GEOMORPHOLOGY OF SOUTHERN MARGINAL FAULT ZONE OF DATONG-YANGYUAN BASIN

Cheng Shaoping, Yang Guizhi

1996, 18(4):  289-300. 

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The southern marginal fault zone of the Datong-Yangyuan basin is the largest fault in the basin-range area of NW Beijing-N Shanxi.Heights of late Quaternary fault-scarps and their a-long-striking distribution Pattern can divide the fault zone into two segments,the southwest(SW)segment and the northeast(NE)segment.Between these two segments there have been significant variations in mountain front and piedmont slope tectonic geomorphology.as well as in evolutional history of micro-physiographic stages.Individual segments have different quantitative mountain front geomorphobgical indices.Means of mountain front sinuosity(S).valley widthdepth relief ratio(V_f),and stream-gradient index(K)are 1.93,0.49 and 27.18,respectively,for the SW segment,wherea are1.57,0.39 and 56.61,respectively,for the NE segment.The SW segment piedmont slope is characterized by the landform assesbles of youngest alluvial fan A₃(Q₃²+Q₄¹)inerted into older fan A₂(Q₃²),indicating that an upwarping of the near-fault part of older fan A₃(Q₃²)might have occurred during late Quaternary.On the contrary,the NE segment peidmont slope is characterized by the landform assembles of youngest fan A₃(Q₃²+Q₄¹)overlapped onto oldest fan A₁(Q₃¹),showing that a downwarping might have occurred on the near-fault part of oldest fan A₁(Q₃¹).Before 36 8000a B.P,the NE segment might have experienced an evolutional history of erosion～aggradatin～erosion,while the SW segment minght have had evolutional stages of aggradation～erosion～aggradation.Tectonic geomorphological process rates,fault behavior,and segment boundary charateristics seem to be reasons of such segmented varations in tectonic geomorphology of the fault zone.During late Quaternary,the SW segment has a lower faulting rate relative to a fluvial downcutting rate,which were estimated to be 0.34mm/a and 0.41～0.48mm/a,resepectively.Displacement per event was averaged 0.9m ad recurrence interval was estimated to be 900～1000a.the NE segment has a higher faulting rate relative to a flurial downcutting rate,which were estimated to be 0.99mm/a and 0.22mm/a,respectively.Displacement per event was averaged 3.1m and recurrence interval was estimated to be 1800a.Furthermore,it is the overlapping faults between the SW segment and the NE segment to become the segment boundary,where a tectonic effect of displacement deficit might have occurred,playing and important role in such segmented variations in tectonic geomorphology.

A STUDY ON THE RELATION BETWEEN QUATERNARY RIGHT-LATERAL SLIP AND TIP EXTENSION ALONG THE HONGHE FAULT

Guo Shunmin, Xiang Hongfa, Ji Fengju, Zhang Wanxia

1996, 18(4):  301-309. 

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Since Quaternary,large-scale right-lateral movement has occurred along the Honghe fault.It leads to mass loss and results in extensional area at the tip of the northern segment of the fault.In spatial distribution the strike-slip segment and the extensional area are correlated each otherand belong to a system.The direct evidence for strike-slip of the fault includes a number of phenomena such as linear geomorphic feature,steep fault plane,nearly horizortal fault scratch,and water-system offset.The extensional area is indicated by the en echelon normal faults,basins,turns and branches of the fault end which were developed on the northern segment of the Honghe fault.The activity of the strike-slip segment and fractures and basins in the extensional area is synchronous and occurred in Quaternary.The right-lateral strike-slip occurring along the strikeslip segment of the fault is about 7.1km,which was transformed into the extensional area at the end of the fault associated with the block motion.The amount of extension in the right-lateral direction of the extensional area is about 5.35km,comparable to the strike-slip movement.Therefore the genetic relationship between the two types of tectonic deformation has been confirmed quantitatively.

PREDICTION OF BAOTOU EARTHQUAKE Ms6.4 AND ELECTROMAGNETIC RADIATION

Mao Pushen

1996, 18(4):  310-312. 

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STUDY ON ACTIVITY OF THE NANKOU MOUNTAIN FRONTAL FAULT IN BEIJING

Che Zhaohong, Wang Guangyu

1996, 18(4):  313-318. 

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The deformation and gravity remeasurement data which are used to monitor the activity of the Nankou mountain frontal fault in Beijing is analysed systematically.It is suggested that each segment of the fault shows differential activities.The segment from Shangkou to Nankou has small amplitude of activity.The Nankou-Baiyangcheng segment has persistent activity at a larger rate.The Baiyangcheng-Mabaoquan segment is characterized by discontinuous wrench or tensional movement.The style of the fault may have been changed prior to and following major earthquakes.The development process of major earthqukae may be representative of the regional tectonic activity.The deep activities of each segment of the Nankou mountain frontal fault are in unity and there exists local strong tectonic motion.Much attention should be paid to this fault,in particular to the Nankou-Baiyangcheng segment.where major earthquakes may occur.

DISCUSSION ON THE CHRONOLOGY OF RECENT FAULT ACTIVITY IN BEDROCK AREA

Shi Lanbin, Lin Chuanyong, Liu Xingsong, Tang Hanjun, Chen Xiade, Li Zuxin

1996, 18(4):  319-324. 

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The study of recent fault activity in bedrock area,where no young sediments can be observed,is often fulfilled through the study of fault zone materials.The authors proposed that the formation periods of fault zone materials should be classified through macroscopic observation in the field and the microscopic analysis of the deformation features.The radiometric dating of the materials of different periods then can be carried out separately.For some dating techniques,it is necessary to determine the degree of "annealing" of the fault zone materials.Then a decisive result with reasonable interpretation can be obtained.

ISOTOPE STUDIES OF SHIHUA CAVE-I:δD,δ¹⁸O AND TRITIUM ACTIVITY OF SHIHUA CAVE,BEIJING

Li Hongchun, Teh-Lung Ku, Zhao Shushen, Liu Tungsheng, Jiao Wenjiang, Yin linhui, Li Tieying, Lu Jinbo

1996, 18(4):  325-328. 

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We have measured δD, δ¹⁸O and ³H of surface water, spring water and drip water in Shihua cave area.The average values with the standard deviation of δD and δ¹⁸O are (-65.4±3.5)‰, (SMOW) and (-9.4±0.3)‰(SMOW), respectively.The average tritium content is (30.8± 4.5)TU.These data demonstrate that the drip water in Shihua cave represents fast penetration of surface water above the cave, and the mixing effect of old groundwater is negligible.Therefore, the variations in isotopic composition of cave drip water can reflect changes in isotopic composition of surface water which represent weighted mean annual isotopic composition of precipitation in the locality.The major factors that influence isotopic composition of cave drip water are mean annual air temperature, mean annual rainfall and change in moisture source.This research work forms the basis of using high-resolution δ¹⁸O record in speleothem to reconstruct paleoclimatic record in the region, especially for paleomonsoon variability.

ISOTOPE STUDIES OF SHIHUA CAVE, BEIJING (Ⅱ):RADIOCARBON DATING AND AGE CORRECTION OF STALAGMITE

Li Hongchun, Teh-Lung Ku, Chen Wenji, Jiao Wenqiang, Zhao Shusheng

1996, (4):  329-338. 

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The application of radiocarbon dating of speleothems is often limited by "dead carbon" contamination.In this paper we have established a new model to correct contamination of "dead carbon" and determine growth rate of a stalagmite which was collected from Shihua cave, Beijing.Based on the measurements of ¹⁴C activity on 11 samples from the stalagmite, we have found that 5 of the samples have little "dead carbon" contamination and four of the samples contain relatively constant contamination of "dead carbon".The two groups of the samples gives us two linear relationships between natural log of ¹⁴C activity and depth with the same slopes but different intercepts.These data results illustrate that the stalagmite has a relatively constant growth rate and no growth hiatus which are the assumptions of the model.Using the model we have reconstructed the chronology Of the stalagmite and obtained a mean growth rate of 0.042 mm/a.The results are in good agreement with the mean growth rate determined by the annual growth banding and the youngest age measured by ²¹⁰Pb method.

Brief Report

THE LOESS AND THE PALEO-ENVIRONMENT FOR ITS FORMATION IN THE LINFEN BASIN OF SHANXI PROVINCE

Wang Kelu, Sheng Xuebin, Yan Fuhua, Liu Huimin, Mai Xueshun

1996, 18(4):  339-348. 

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The Linfen basin is situated in the middle part of Shanxi Province,where loess.is widespreadly,successively deposited and forms a complete stratum.Therefore,it is one of comparative ideal area for study of paleoclimate change.The loess in Linfen basin,chrono-logically can be divided into Upper Pleistocene Malan loess,Middle Pleistocene lishi loess,and Lower Pleistocene Wucheng loess.The loess in Linfen basin has been so far in a tectonic uplift environment in the context of its formation.In particular,the tectonic uplift has been more sharp in the post deposition period of the loess,since the later stage of middle pleistocene.The loess in Linfen basin,like that on the middle reach of the Huanghe river, was formed in a arid paleoclimate environment.In the process of their formation,there were 20 alternative warm-humid climate with arid-cold climate and there were 3 notable deterioration phases.Each climatic cycle consists of a warm-humid stage and an arid-cold stage.Totally 18 climate groups can be formed.These climatic groups and climatic cycles can be compared with paleoclimatic Change curve obtained by oxygen isotope study of cores of V_28～239 drillholes.

CHARACTERISTICS OF THE WNW TRENDING NANSHANCUNCHAKOU ACTIVE FAULT IN CIXIAN,HEBEI PROVINCE AND RELATIONSHIP WITH 1830 CIXIAN EARTHQUAKE

Jiang Wali, Zhang Yingli

1996, 18(4):  349-357. 

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The paper deals with new information about the Nanshancun-Chakou active fault.The total length of the zone is about 35 km.It is divided into two segments, respectively 5km and 15km.The style of the active fault is normal-dip-slip accompanied by sinistral stike-slip.The active fault had many times of activity during Holocene.There was ground surface fracture zone along the active fault in 1830 earthquake.The northern side of the fault fell down.The vertical displacements on the ground along the fault are mostly 2-4m.The recurrent interval of the latest two times of destroyed earthquakes along the fault was about 3 500a according to the research.The paper will show the evidence to explain the serious destruction of the ancient temples along the fault in the 1830 earthquake from the the records carved in stones of the temple.

ESR DATING OF CALICHE IN LAKE DEPOSIT FROM THE YANQING BASIN,BEIJING

Yin Gongming, Lu Yanchou, Gao Juncheng

1996, 18(4):  358-360. 

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The Yanqing faulted basin has been developed since the late Cenozoic.It is confirmed that there are lake Quaternary sediments in the basin.ESR technique was used to date samples of the caliche in lake deposit exposed on the surface from the Yanqing basin, Beijing.The results indicate that it is possible to date caliche by using ESR technique,and the estimate of age for the lake deposit in question has been conducted.

SIMULTANEOUS INVERSION OF GRAVIMETRIC AND MAGNETIC DATA CONSTRAINED WITH INTERNAL CORRESPONDENCE ANALYSIS AND ITS APPLICATION TO THE TARIM BASIN

Li Yishi, Yin Xinhua, Lin Zhanpo

1996, 18(4):  361-368. 

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Gravimetric and magnetic data are useful to study the deep geologic structures,but interpretation is usually difficult because of the multi-solutions of inversion and complex field geology.We have developed an enhanced technique of constrained simultaneous inversion based on the classical inversion and internal correspondence analysis (ICA) ,which is to weight the object function of simultaneous inversion with relation coefficients of the gravimetric and magnetic data.The theoretical modeling results show that the new technique is helpful to the convergence of iteration.Appliation of this method to the Kuerle-Ruoqiang profile of the Tarimu basin shows that a reasonable initiative model for further optimistic iteration can be established with the help of the information from the ICA.

JOINT GRAVITY-SEISMIC INTERPRETATION FOR YINGXIAN-ZIBO PROFILE

Liu Changquan, Fang Shengming, Li Changfa

1996, 18(4):  369-374. 

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Using 2-D velocity structure from interpretation of DSS data of Yingxian-Zibo profile we present preliminary basic model.The values of gravity anomaly are calculated and the 2-D block density distribution is inversed making use of the block 2-D body mdel of any polysonal section.The computed results show that the detachment between the upper and the middle crusts is an obvious density interface.The strong velocity gradient,i.e.the crust-mantle transition zone in the bottom of the lower crust is a high density layer and the lower-velocity block within the middle-lower crusts beneath Wutai Mt.is a lower-density block.

DEEP VELOCITY STRUCTURE IN THE TIANSHAN REGION

Xu Yi, Feng Xianyue, V. I. Shstsilov

1996, 18(4):  375-381. 

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In terms of inversion results from P arrivals of local earthquakes,crustal velocity structrues have been investigated along the Tianshan from Xinjiang of China,Kazakhstan,to Kirghiztan.5 largEr blocks can be divided according to different features,indicating an inhomogeneous crust composition.Those low velocity belts in the crust psrts of foothills are believed to be the deep marks of the Tianshan in collision with surrounding blocks.The Tarim,Junggar and Ili blocks all have a trace of underthrusting the Tianshan.

MOHR CIRCLE ANALYSIS 3D MAGNETOTELLURIC IMPEDANCE DATA AFFECTED BY DISTORTION

Jin Guangwen, Jiang Zhao, Sun Jie

1996, 18(4):  382-390. 

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Mathematical formulas of three-dimensional(3D) Magnetotelluric(MT) responses affected by shear,twist and anisotropy are derived based on the principle of two-dimensional(2D) MT impedance tensor decomposition,which are applicable not only to complicated 3D structure,but also to 2D or 1D situations.Mohr circle analysis are also made for 3D MT responses and the properties in the cases of both weak and strong distortions.

PREDICTION OF SEISMIC RESPONSE TO SITE EFFECT OF SURFACE GEOLOGY

Xu Guoming, Chen Jinbo

1996, 18(4):  391-397. 

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Blind test for site effect of surface geology the authors took part in,is discussed in this paPer.This international exPeriment was held in Turkey flat,California,USA.We well predicted the seismic vibration at the experimental site of Turkey flat by the propagation-matrix method and the corresponding computer software was developed by us,The results of the blind test show that parameters of geology model are very important for the prediction of the response of surface seismic shake.Comparing the observed data and results of computation reveals that incident angle of seismic waves,velocity of S wave,Q value of strata media as well as depths of interfaces all have the noticable influence on the prediction of seismic vibration.

RESEARCH ON CURIE ISO-GEOTHERMAL SURFACE IN BOHAI SEA AND ITS ADJACENT REGION

Liu Guangxia, Zhang Xian, He Weimin, Shen Jingxiu, Tang Xifeng

1996, 18(4):  398-402. 

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In this paper,the authors use 3-D magnetic stratum inversion calculation to study the relief of Curie iso-geothermal surface in Bohai Sea and its abjacent regions,and along with the surface heat flow,the electrical structure of crust and upper mantle,analyze the deep seated geological characteristics.It is found that in Bohai Sea and the region from Kenli to Huanghekou in the northern part of Qiyang depression,the depths of Curie surface is only 13～20km while it reaches 22～24km at Jiao-Liao and Chengde region.The aim of our research is to Present new suggestions for the earthquake zoning and the earthquake disaster prevention.

THE PHYSICAL DYNAMIC BEHAVIOR OF GROUNDWATER IN THE TAIPINGZHUANG WELL,BEIJING

Zhu Qingzhong, Tian Zhujun, Gu Yuanzhu

1996, 18(4):  403-408. 

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Based on the physical dynamic behavior of groundwater including water-level,flux and water temperature,and their relative tides effect of inverse transmission of the water press caused by accumulated water in the depressions,effect of the damming flow,rapid-fall coseismic behavfor of water temperature and abnormal behavior of sharp flux change before earthquake,their micro-behaviors as well as the relationship between them and earthquake are discussed.Finally the relative mechanisms are also studied.The result shows that the Taipingzhuang well is important for earthquake monitoring prediction,especially in the capital region.

PRELIMINARY DISCUSSION ON GEOCHEMICAL INDICATOR FOR THE SEGMENTATION OF ACTIVE HIDDEN FAULT

Wang Jihua, Wang Liang, Sun Fengmin, Jin Xiaowei

1996, 18(4):  409-412. 

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In this paper,some examples of segmentation of active hidden fault are introduced by using mercury measurement as well as a preliminary discussion on mercury geochemical indicator for different segmentation of active hidden faults.If the buried depth of a hidden fault is relatively shallow (severial to tens of meters) and the average background value of mercury for the traverses along the hidden fault is the same on the whole,it is possibly effective to make segmetation of the active hidden fault by using mercury measurement.Meantime some questions related to segmeatation of active fault are discussed as well.

ANALYSIS OF THE TEST FOR THE FAULT PRODUCT GAS IN PINGGANG FAULT

Zhao Hongmei

1996, 18(4):  413-416. 

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Based on the previous research and our latest chemical exploration,the more exact location of the Pinggan fault has been determined.By the comparison with the test values,we found that the fault along the southwestern section is bigger than that along the northeastrn part.A trial investigation on the recent activity of the fault has been made as well.

RELATIONSHIP BETWEEN THE ANOMALOUS RELEASE OF SUBSURFACE HELIUM AND HYDROGEN GASSES AND THE THREE MAIN ELEMENTS OF EARTHQUAKE PREDICTION

Fan Shuquan, Song Guanyi

1996, 18(4):  417-420. 

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Based on the measuing data from 9 observation points and the cases of 5 moderate earthquakes in North China during the time period from 1989 to 1991,the relationship between the anomaluos release of subsurface helium and hydrogen gasses and the occurrence time,locality and magnitude of earthquake has been discussed in this paper.An empirical method was proposed for determining the three main elements of earthquake prdeiction.It is proposed that the occurrence time of a possible earthquake can be predicted on basis of synchronus anomaly of helium and hydrogen in various observation points, and specially the dropping and truning of the curves of anomalies.The possible locality of earthquke occurrence can be delineated according to the fact that the starting time of the anomaly becomes later toward the epicentral area,i.e.the closer to the epicentral area,the later the starting time of the anomaly.The magnitude of the predicted earthquake can be estimated through the intensity (a combination of duration time and amplitade )and range of anomaly,as well as the number of the observation points that show anomalous release of helium and hydrogen gasses.

A STUDY OF PREDICTION METHOD FOR RESERVOIR INDUCED EARTHQUAKES

Sun Junxiu

1996, 18(4):  421-426. 

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A method of predicting the upper-limit of the potential magnitude of reservoir induced earthquakes is proposed by using fuzzy cluster and grey cluster analyses.The applicability of the method has been discussed by taking Xinfengjiang reservoir area as an example.Fuzzy cluster analysis:A fuzzy subset should be set up at first.The fuzzy subset is defined by the function μ=A(u),where μ is called the subordination function of A.If its image is to be demonstrated,the threshold value λ which is between 0 and 1 must be chosen.If A(u)≥λ,then it is the case of u∈A or otherwise u∈A.In fuzzy cluster analyses, if R_λ is in fuzzy equivalence relation to U,then R_λ is in common equivalence relation to U for any 0≤λ≤1.According to this equivalence relation,the elements in U can be classified.When λ declines from 1 to 0, the classifications change from detailed to sketch,and then merge gradually,forming a dynamic image of cluster.In grey cluster analysis,prediction is made by using the grey target of the cluster.The object of the cluster is classified according to the grey type of different target, i.e.to take the weight of the collected samples by using statistic method,and to determine the value characteristic of the state of the predicted object on the weight function.The type then can be decided according to the magnitude of the value.Reservoir induced earthquake is a function of various factors.In the prediction,the depth and volume of the reservoir,the state of regional stress, fault activity, lithology and seisimicity background are taken as cluster factors, while the magnitude of reservoir induced earthquakes is taken as type and the predicted resevoir as the object.The results show that the predicted upper-limit magnitude is coincident with the actual case of earthquake occurrence.

THE INDICATOR SYSTEM OF NET DEFORMATION RATIO(NDR)OF CRUSTAL MOVEMENT AND SEISMIC EVENT

Huang Xiuming

1996, 18(4):  427-435. 

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This paper deals with the indicator system of net deformation ratio (NDR) of crustal movement,such as the bending deformation ratio in horizontal direction on the land surface S,the differential movement ratio in the vertical direction on the land surface τ,and the total deformation strength of crustal movement M_t.NDR system is a suit of dynamic geological indicators for quantitating seismic risk.We have made compution on NDR system of crustal movement prior to 5 earthquakes(M>6)occurring in 1966～1996 in the North China,and have found a close relation between abnormal mark on NDR system and seismic event.This method is used in forecast of earthquakes,engineering seismology,evaluation of crustal activity and study of geodynamics.

THE GREY PREDICTION OF SEISMIC ACTIVITY IN THREE-GORGE OF CHANGJIANG RIVER AND ITS NEIGHBOURING AREA

Hu Daogong, Tan Chengxuan, Wu Shuren

1996, 18(4):  436-442. 

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On the basis of histrical earthquake data and the observations two grey forecasting models for the next seismic activity period and the maximal magnitude of earthquakes which may occur within the period are constructed by means of grey system theory.The two models have predicted that the next seismic activity period will last for 79a, and that the maximal magnitude of earthquakes occurring within the period would not be more than 5.2.The results provide an imortant evidence for assessment of earthquake risk and precaution of disasters in the Three-Gorge area.

DISTRIBUTION OF THE CRUSTAL HEAT PRODUCTION IN YUNNAN

Zhou Zhenheng, Xiang Caiying

1996, 18(4):  443-452. 

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Learning the vertical distribution of the radioactive heat production of rocks is the foundation of studying the crustal thermal structure.On the basis of seismic data and relationship between the seismic velocities and heat production we have estimated the vertical distribution of the heat production for the crust of Yunnan Province.The results indicate that the general heat production is 0.8～2.1μW/m³ for the upper crust,0.4～1.2μW/m³ for the middle crust,and 0.11～0.55μW/m³ for the lower crust.

CATALOGUE OF RESERVOIR INDUCED SEISMIC EVENTS IN THE WORLD

Yang Qingyuan, HU Yuliang, Chen Xiancheng, Chen Lingyue

1996, 18(4):  453-461. 

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A SOFTWARE SYSTEM OF EVALUATING EARTHQUAKE CASUALTIES

Cheng Jiayu, Yang Zhe

1996, 18(4):  462-470. 

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The software system consists of the historical data base of the earthquake casualties,the population data base and the calculating programs.The number of casualties by Tangshan earthquake and Xingtai earthquake was collected to build up the historical data base in which the injured can be divided into the dead,the serious injured and the light injured.The main type of the buildings related to the record in historical data base was given by the statistical results according to the interpretation from aeral photos which were taken after th shock.Based on the historical data,the death ratio related to the building for each intensity was calculated,so did the serious injured and the light injured.The population data base in Beijing and its adjacent areas,using the number of populations by the end of 1994,is built up to meet the needs for evaluating the casualties in the assumed coming earthquake.A special program designed makes the evaluating casualties as quickly as possible,where the intensity lines is digitized by the digiter,and the record in population data base is checked by the intensity lines to determine the related values.It follows that the mumber of evaluating casualties should be available in a short period of time after shocks.The system formulates the evaluating method in taking the probabilities of people staying in the buldings in each time as a modification factor to correct the number that varies with the earthquake occurring time.As a subsystem of evaluating earthquake disasters,it is mainly used in fast evaluations.