SEISMOLOGY AND GEOLOGY

THE INVESTIGATIONS OF DEFORMATION TRACES OF Ms=8.0 EARTHQUAKE IN HONGDONG, SHANXI PROVINCE

Meng Xianliang, Yu Shene, Xi Yun

1985, 7(4): 1-10.

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The authors investigated the active faults in the Linfen basin,Shanxi Province and discovered many earthquke defortmation traces in the foreland of mountains from the Hongdong county to Huo county on the eastern boundary of the Linfen basin.We considered that these were the result of Ms = 8.0 earthquake of 1303.The discoveries are likely to provide new data for further study of the earlest Ms = 8.0 earthquake drcumented on the historical record.In this paper.We have described the earthquake deformation traces discovered in good detail,and made a preliminary discussion of problems concerning the great earthquake of 1303.

THE PREHISTORIC MAJOR EARTHQUAKES FOR HAIYUAN ACTIVE FAULT

Liu Baichi, Zhou Junxi

1985, 7(4): 11-21.

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There are geological and microgeomorphological evidences that for the Haiyuan fault there have been 5 major earthquakes with a magnitude of about 8.5 since the Holocene,among which the earthquake of 1920 is the latest.The ¹⁴C dates forthe others are 3680?60,6300?70,7830?>103 and 9360?75 B.P..respectively.It can be found that there has been an evident increase of the interoccurrence time for these events since that time.

THE APPLICATIONS OF LICHENOMETRY IN SEISMIC RESEARCH

1985, 7(4): 22-22.

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INVESTIGATION ON THE HOIOCENE ACTIVITIES OF THE HELAN MOUNTAIN PIEDMONT FAULT BY USE OF GEOMORPHOLOGICAL METHOD

Yang Jingchun, Guo Zhengtang, Cao Jiadong

1985, 7(4): 23-31.

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This paper deals with the Holocene activities of the He an Mountain piedmont fault on the basis of morphometric data of nickpoints and terraces along 45 gullies strentching across the mountain flank and of inclinations for various parts of the fault scarp.We have come to the conclusion that there were at least 8 events in the Holocene,the last one leading to an offset of the Great Wall 400 years ago and to nickpoints on the gullies,at a distance of about 5 m from the fault scarp.Under the condition that the last event for the fault was associated with Ping Luo earthquake of 1739 we may estimate the average rate of headward erosion for the gullies resulting from uplifting of the fault scarp to be 2.0-2.5cm/yr.Based on the distance between the two neighbouring nickpoints,the average rate mentioned above and the climate of China showing a tendance to have come drier and drier in the last 5000 years,we have worked out the cycles of activity for the Helan Mountain piedmont fault as shown in Table 3.From relative height for varios terraces near the fault scarp we have calculated the amplitude of movement of the fault occurring during each cycle (Table 4).

A PRELIMINARY STUDY ON THE LATE PLEISTOCENE STRATIGRAPHY ALONG THE COASTAL AREAS OF SOUTHERN FUJIAN

Yao Qingyuan, Zhang Hunan, Zhang Jingwen, Zhao Xitao

1985, 7(4): 32-40.

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In the coastal area of Southern Fujian,the late Pleistocene sediments have a wide distribution (Fig.1).The late Pleistocene strata are mainly composed of following sediments in ascending order:Dgrey medium-fine sand,2)black mud or peat,and 3)yellow sand and sandy clay.The other possible late Pleistocene deposits,so-called "Old Red Sand",are the semi-cemented,well-sorted,and red quartz silt-fine sand.These deposits are distributed over the bays and gullies of mainland and the islands,and constitute the second terrace,tiebar and other littoral accumulation landforms.In this paper,a number of natural outcrop sections of late Pleistocene strata have been described and drown in Fig.2.Based on the sedimentologic and geomorphologic investigation in the field and the data of ¹⁴C dating (Table 1),analyses of foraminifers and ostracods (Table 2) and pollen analysis (Table 3),the following conclusions can be obtained:1.The grey and yellow sand and sandy clay intercalated with black mud or peat belong to the late Late Pleistocene,i.e.the middle and late pleni-glacial substages of the last Glacial Stage,between about 40,000 and 16,000 years B.P..2.The grey and yellow sand and sandy clay,especially the black mud or peat,of the late Late Pleistocene are mainly the deposits of marine-land transitional facies,in part the littoral,and in part lake and swamp facies.3.On the whole,the climate of the late Late Pleistocene was warm and humid,but sometime cooler and drier.4.The "Old Red Sand" is the littoral sediments which were deposited under the heat and humid climate.It might be deposited during the late stage of Late Pleistocene,but the possibility of forming in the earlier period can not be ruled out.

SOME PROBLEMS OF MEASURING TAMPERATURE AND PRESSURE IN THE DIAMOND-ANVIL ULTRAHIGH PRESSURE AND HIGH TEMPERATURE DEVICE

Xu Huaiji, Guo Jindi

1985, 7(4): 41-48.

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The use of optical pyrometer to measure temperature in diamond-anvil ultrahigh pressure device is different from that under normal conditions because the temperature is measured through the optical system of microscope.Therefore,a caribration is recessary for the used optical pyrometer.There exists an interference from miscellaneous light in using the ruby R₁ fluorescence technique to measure the pressure.In this paper,we introduce a method of temperature calibration for optical pyrometer and discuss how to estimate the pressure in the region of interference.

EXPERIMENTAL STUDY ON THE RELEASE OF SEALED H₂ FROM BASALT ROCK UNDER ULTRASONIC VIBRATION

Feng Wei, Wang Zhenguang, Wang Jianqiu, Wang Gengzhou

1985, 7(4): 49-55.

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This paper discusses ultrasonic mechanism of the sealed-H₂ release from basalt rock on the basis of experiments.A small amount of released H₂ by ultrasonic vibration is escaping H₂,whereas most H₂ is absorbed H₂.Both phenomena can be regarded as a precursory H₂.So,it is possible to use H₂.to.forcast earthquake.Seeing that the intensity of u.v.and the its duration were constant in the experiments and the amount of released H₂ gas increased during each vibration,abnormal H₂ seems not to be representative of accoustic emission intensity,thus suggesting that the intensity of the failure of rock may be representative of the earthquake magnitude.

AN INVERSION METHOD ON TWO-DIMENSIONAL MAGNETOTELLURIC MODEL

Zhao Guoze, Liu Guodong

1985, 7(4): 56-58.

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A PRELIMINARY ANALYSIS ON DYNAMIC STATE OF RECENT TECTONIC MOVEMENT IN THE WENAN AND BAXIAN AREA OF THE HEBEI PLAIN

Gui Kunchang

1985, 7(4): 59-67.

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On the basis of spatial and temporal characteristics of vertical deformation in the study area as shown by data obtained from repeated levelling,dynamic state of recent tectonic movement is described in this paper.It is suggested that a N-S slip of the block was accommodated along the low angle fault before and after the Tangshan earthquake.Moreover,in view of changes in deformation following the shock in point the stress accumalation might be on the front of the slipping block,suggesting an increase in tectonic stresses in the southern part of the North China plain.It is concluded that historically seismic zones and those in the process of being deformed,which have NW-treniding structures acting as a barrier to shocks can regarded as seismically potential regions.

THE APPLICATION OF FINITE ELEMENT ANALYSIS OF MICROSTRCTURAL STRESS FIELD TO THE STUDY OF CAUSATIVE MECHANISM OF PRESSURE SOLUTION

Lin Xiaohui

1985, 7(4): 68-70.

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MICROSTRUCTURE STUDIES OF SOME MANTLE PERIDOT1TES IN CENOZOIC ALKALI-BASALTS FROM FANGSHAN,LIUHE COUNTY,JIANGSU PROVINCE

Yan Meie, Wang Wenhu

1985, 7(4): 71-80.

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In this paper microstructure,texture,and preferred orientations in peridotites from Fangshan have been studied and kink structure,glide systems in olivins have been measured primarily.Fangshan is a volcanoc cone which consisted of Cenozoic alkali-basalts as the substances were carried out from upper mantle by volcanic eruptions.The results indicate that crystalline plasticity and solid state flow are characteristic of upper mantle.The upper mantle physical parameters for this region have been calculated as:
Temperature T=1278-1487癒
Confining pressure P= 17.3-30.1kb
Applied stress =214-362b
Depth Z = 57-95km
strain rate = 10^-13...10^-16 strain/sec.
Viscosity =1.3?10²⁰p-1.3?10²³p.

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