• Volume 7,Issue 1,1985 Table of Contents
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    • DISCUSSION ON A KIND OF YEARLY CHANGE IN APPARENT RESISTIVITY OBSERVATION

      1985, 7(1):4-11.

      Abstract (562) HTML (0) PDF 504.85 K (725) Comment (0) Favorites

      Abstract:In this paper,from theoretical calculation and practicaI observation data,we discussed a kind of yearly change which presents low vaIue in winter and high vaIue in summer at some earth resistivity stations in our country.lt is pointed out that there may be three kinds of reasons Ieading to such a yearIy change.Among them the principal one is the contrary con-tribution of resistivity variation in overIayer medium to observed apparent resistivity for some of special geoelectrical profiles,in which the variation of overlayer resistivity results in a non-linear variation of underground current density in a special geoelectrical profile.The overlayer response coefficient sishows the negtive,which is a very apparent mark for such a special geoelectrical Profile.In addition,the eliminating approach about thrs kind of yearly change is also discussed.

    • ANOMALOUS VARIATIONS OF THE AMPLITUDE RATIO CHARACTERISTICS OF THE SEISMIC WAVE BEFORE AND AFTER SOME STRONG AND MODERATE EARTHQUAKES in XINJIANG

      1985, 7(1):12-19.

      Abstract (500) HTML (0) PDF 545.15 K (961) Comment (0) Favorites

      Abstract:In this paper,we make a primary analysis of the temporal-spatial dis-tributions characteristics of the amplitude ratio,including those of the imminent shock anomaly before the 4 strong and moderate earthquakes in kuche-kurle,Xinjiang.
      The preliminary results show that:(1)The amplitude ratio of the maximum vertical displacements of the S and P waves remarkably decreased before and after the strong and moderate earthquakes.(2)During the four months before the shock,near the seismograph stations from their epicnters,the As/Ap appeared suddenly immediately was observed at times.(3)The temporal-spatial distribution of the As/Ap appeared su-ddenly is most concentrated in ten days before the shock.(4)The As/Ap anomalies correspond approximately with the velocity ratio anomalies of seismic waves and duration ratio of the seismic waves.
      Finally,it is suggested that it be possible to make use of the anoma-lies of the amplitude ratio to predict earthquake.

    • STIFFNESS EFFECT OF FAULT ZONE TIP IN HYPOCENTER

      1985, 7(1):20-28.

      Abstract (496) HTML (0) PDF 574.64 K (607) Comment (0) Favorites

      Abstract:Some simplified hypocenter models are presented for explaining an im-portant effect of environmental stiffness,which includes the axial and the lateral stiffness and that of fault zone tips,on shock generation pro-cess of hypocenter.Besides the strength condition,the environmental stif-fness condition is another one necessary for shock-generation.The effect of environmental stiffness may reduce the magnitude of mean stress drop in hypocenter to the order of 102 or even 10 Mpa,and the lower stress drop may occur at higher confining pressure.Some problems are discuss-ed:two different kinds of locking segments on fault zone-the potential “seismic core”and the“tip”which constrains shock-generasion;two pos-sible effects of water injecting into different parts of hypocenter region- inducing or preventing strong earthquake;the relation between the geome-tric parameters of environmental stiffness and the distribution of seismic intensity.

    • FAULT SCARPS RESEARCH AND EARTHQUAKE RISK ESTIMATION-EXAMPLE IN EASTERN HOLANSHAN FAULT SCARPS

      1985, 7(1):29-38.

      Abstract (643) HTML (0) PDF 797.02 K (854) Comment (0) Favorites

      Abstract:This paper deals with the formation and evoluting processes of fault scarps,and proposes that research on fault scarps should be not only on geometry but also on sedimentology.On the basis of research on the eastern Holanshan frontal fault scarps,we realized several characters of fault colluvial wedge and the important sense in studying earthquake occurrenee.
      According to geometry and sedimentary research on fault scarps in Hogguozi valley and Suyukou,four times rapid dislocation events have been indicated in eastern Holan Shan frontal fault since Holocene These four events can be named as A.B.C.D from the oldest to the youngest.The C'1 age of material beneath the second colluvial wedge(B) ls adout 5745±90from now,so event B may occur 6000 years ago.The last event(D)occured within 400 years from now,it displaced the Great Wal-which built 400 years ago.There are two places where Great wall have been displaced, the vertical displacement is 0.35 meter in weastern place and 0.95 meter in eastcrn place. The occurrence interval of four offset ev-ents is estimated as 2000 to 2500 years.According to the hight of ancient colluvial wedge,we estimate the amplitude of vertical displacement as 0.52 to 0.5 meter in western scarp and 0.9 to 1.2 meter in eastern scarp of Hong guozi valley,0.8 to 1.6 meter in Suyukou.obviously they coincide with the event D.If we suppose that event D is associated with Pingluo earthquake in1739,the occurrence interval of the four fault offsets can be seen as the acurrence interval of earthquake with magnitude 7(1)/(2).This occurrence interval coincides with the one which can be calculated by using fault slip rate in same segment of the fault.
      The eastern Holanshan fault in northern Ninxia is a right lateral strike slip to normal fault.Since Holocene its vertical slip rate is 0.2-0.25 mm/year in northern segment,and 0.5-0.6mm/year inmiddle segment.How ever in south of Ninxia,the Southern Huashan to Western Huashan fault is a left lateral strike-slip fault,the horizontal strike-slip rate can be as large as 28.65mm/year since 20000 years.That is because these two faults belong to North China and Qinzang tectonic regions respeetively,so they have different active tectonics and earthquake occurrence.

    • ON THE CONVERSION BETWEEN THE GEOCENTICRIC LATITUDE AND THE GEOGRAHPHIC LATITUDE

      1985, 7(1):39-43.

      Abstract (750) HTML (0) PDF 320.35 K (1010) Comment (0) Favorites

      Abstract:The approximated formula of conversion between the geocentric latitude and the geographic latitude from a basic formula is presented in this paper.And using the recent value of the ellipticity of the Earth(satellite orbit betermination method,1977),we have given the conversion coeffi-cients(βandγ)and a new α-φlist.There is some difference about 5 angle seconds(corresponding to the distance on the surface of the Earth-about 150 meters).It is not neglected for some aspects of GEONOMY to require higher precision of the latitude conversion.Finally,there is a brief discussion on some approximated formulas in this papaper.

    • SOME CHARACTERISTICS OF DEFORMATION IN TIANJIN REGION BEFORE TANGSHAN EARTHQUAKE(M=7.8)

      1985, 7(1):44-47.

      Abstract (523) HTML (0) PDF 273.90 K (601) Comment (0) Favorites

      Abstract:This paper holds that the measurement data,both from Panzhang fluid levelling and from Zhangdaokou short levelling,are the mid-short term anomalies of Tangshan earthquake.Its anomalous deformation value is lar-get than that in the epicentral area.It is of“stress adjustment element”.

    • FAR-FIELD RADIATION THEORY FROM A RECTANGULAR FAULT WITH UNIFORMLY VARYING VELOCITY

      1985, 7(1):48-58.

      Abstract (510) HTML (0) PDF 583.35 K (810) Comment (0) Favorites

      Abstract:The far field displacements radiating from a rectangular fault with uniformly varying velocity are studied in this paper.An analytic solution to the general form of this problem is obtained.The assumptions are:
      1)When 0 ≤ t ≤ V2-V0/a1,the instantaneous Vt is:
      Vt=V0+a1 t
      where V0 is initial rupture velocity,a1 is rupture acceleration.(a1= constant)
      2)When V2-V0/a1 ≤ t ≤ V2-V0/a1+tu(2),Vt is Vt=V2
      tu(2)=a1(2a1L-V02)-a3(V22'-V02)/2a1a3V2
      where V2 is maximum rupture velocity,a2 is deceleration(a2=const-ant),and L stands for the length of rupture.
      3)When V2-V0/a1+tu(2)≤t ≤ V2-V0)/a1+tu(2)+V2/a3,Vt is:
      Vt=V2-a3t
      where a1 is not equal to |a3|.
      4)Cracking starts from an initial length of which is considered as zero in this paper.
      Above all,V0,V2,a1,a3 and L are parameters.

    • THE NILKE GREAT EARTHQUAKE(M=8.0, MARCH 8,1812, XINJIANG)

      1985, 7(1):59-65.

      Abstract (568) HTML (0) PDF 522.98 K (600) Comment (0) Favorites

      Abstract:The earthquake of M=8.0 in the Nilke county,Xinjiang,on March 8, 1812,caused the violent deformation of the earth surface and produced a zone of the seismical fault about 65 km long.Within the zone,the maxim-um vertical offset measured is 10 m and the right-lateral offset more 1.5m There are also many structural collapses,landslips eboulements in the ma-gistoseismic area where the largest collapse is about 2km2,the widest back margin of landslip about 2km long,and the epicenter intensity over 11.
      In this paper,based on the field investigation,the data from the his-torical records and the interpretation of aerial photographs,we not only have plotted the isoseismic map but had a discussion and calculation about the magnititude of the earthquake,the epicentral location,the source depth,the seismic moment,the stress drop and the solution of focul me-chanism of the Nilke earthquake.Furthermore we have made preliminary research on the seismological background of the Nilke earthquake

    • THE SEISMIC AND GEOLOGIC CONDITIONS OF THE EARTHQUAKE IN HUAXIAN,SHANXI(M=8.0, JAN.23, 1556)

      1985, 7(1):66-74.

      Abstract (606) HTML (0) PDF 633.36 K (760) Comment (0) Favorites

      Abstract:This paper relates to the recent and present rupture activities in the maximum intensity area of the Huaxian great earthquakes(M=8.0,Jan. 23,1556)and makes an analysis of neutectonic stress field.It tells the tectonic sites where the earthquake occurred,estimates the period of earth-quake occurrence in this area and probes by means of the finite element method into the relation between the underground stress and the Huaxian gear earthquake.

    • THE INFLUENCE OF THE DIFFERENTIATION OF THE UPPER MANTLE AND THE LOWER PART OF CRUST ON THE EARTHQUAKE MECHANISM

      1985, 7(1):75-81.

      Abstract (460) HTML (0) PDF 552.53 K (690) Comment (0) Favorites

      Abstract:This paper accents the influence of the differentiation of plate subdu-ction zone and the interia of crust on earthquake mechanism.It holds that because of structure motion and the heterogeneity of the earth rotation velocity,the different diapire structure is apt to be formed at the top of basalt or the upper mantle near abyssal faults.The vertical force caused by such an uplift can make ground surface form synchronous rise and la-teral fall,and epicenter is often considered to lie in the sides or at the top of diapire structure.A superimposed epicenter stress field is made of the superimposition of the horizontal structure stress field and the verti-cal force of diapire structure.

    • THE DATA FROM GEOPHYSICAL EXPLORATION OF THE EARTHQUAKE REGION IN CHANGMA,GANSHU PROVINCE(1932, M7.5)

      1985, 7(1):82-85.

      Abstract (436) HTML (0) PDF 237.68 K (630) Comment (0) Favorites

      Abstract:Thirteen electrical sounding profiles have been made along the fracture zone of the earthquake of magnitude 7.5 in Changme,Ganshu Province. The results of these profiles are used to study the distribution of the fracture zone of the earthquake and its relation with the distribution of Quaternary faults.The relation between Quaternary faults and older ones are studied by analysing geology in Changma and its surrounding area.All of this is followed by the analysis of the structural condition and the ways of the function of the structural stress.

    • SEISMIC ATTENUATION AND EXPLOSION SPECTRA FOR DEEP SEISMIC SOUNDING IN THE STUDY OF THE CRUSTAL AND UPPER MANTLE STRUCTURE

      1985, 7(1):86-93.

      Abstract (504) HTML (0) PDF 502.47 K (735) Comment (0) Favorites

      Abstract:We have analysed,in detail,seismic trace for the shot point and dif-ferent receiver points and proposed different explosion spectra on the ba-sis of modes explosion of such as underwater,cluster in the wells,blast and cave explosions and observable seismic data in the region about 5- 250km.The predominant frequency is 6,7,5 and 9 Hz for underwater, cluster in the wells,blast and cave explosions respectively.The attenuat-ion of peak-value of ground maximum velocity with distance is represented by(R/W1/3)-1.5-(R/W1/3)-1.6We have simply analysed the relation-ship between the observable distance and charge as well.

    • Discussion on Earthquake Prediction by Means of the Stereoscopic Cross Model

      1985, 7(1):100-101.

      Abstract (449) HTML (0) PDF 485.04 K (487) Comment (0) Favorites

      Abstract:在把地震带的延伸方向与地面上可见的或可判的构造带的方向作对比的时侯,人们发现在很多情况两者是一致的,另外也有不少情况两者是不一致的。前一种情况的道理显而易见,人们也讨论较多,而后一种情况人们却讨论很少,有时只是用隐伏构造这一简单名词作回答,并未阐明其成因问题。本文从震源物理的角度提出立交模式*来阐明这个问题并试图把其应用于地震预报。

    • DILATION-CREEP MODEL OF EARTHQUAKE SOURCE DEVELOPMENT AND THE TANGSHAN EARTHQUAKE

      1985, 7(1):102-120.

      Abstract (535) HTML (0) PDF 1.05 M (446) Comment (0) Favorites

      Abstract:The article has made a simple exposition of the dilation-creep model of earthquake source development(abbreviated DC).Inelastic volumetric dilation of rock masses and fault creep are considered as two basic phys-ical processes in the DC model. The physical mechanism of precursors of the M=7.8 Tangshan earthquake has also been analysed and discussed in this paper. The results show that the precursors of the Tangshan earth-quake were not caused by only one factor and the precursors observed in-and around the epicentral area prior to this earthquake can be grouped in to three types. TypeⅠ precursors may be causally related to rock dilata-ncy. Type Ⅱ precursors result from fault creep. Type Ⅲ precursors may be associated with some sort of upward migration of mass in the crust or the upper mantle, and/or may be attributed to large scale stressing process accommodated by some combination of stable slippage and discontinuous brittle rupture (namely small earthquake) along the faults. It was sug-gested that repeated dilation and discontinuous creep occurred during the process of source development of the Tangshan earthquake and the prepa-ratory process of the Tangshan earthquake can be divided into the follo-wing six phases: elastic stress accumulation(from 1954 to 1967);earlyinelastic dilation(from 1968 to 1969);early fault creep(from 1970 to 1973);the second dilation(from the end of 1973 to the first half of 1975);the second evident fault creep(from the second half of 1975 to the end of Apr.1976);and fault creep just before the main shock(from the end of Apr.1976 to the occurrence of the Tangshan earthquake).It is regarded hat the preparatory process of the Tangshan earthquake,as one of the intraplate events,may be controlled jointly by the upward migration of deep mass and large scale intraplate stress field.This characteristic prob-ably is different from that of earthquake along plate boundary.

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