• Volume 3,Issue 3,1981 Table of Contents
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    • APPLICATIONS OF FUZZY MATHEMATICS TO EARTHQUAKE PREDICTION AND INVESTIGATION OF THE PREPARATORY MODEL OF EARTHQUAKE SOURCE

      1981, 3(3):1-8.

      Abstract (483) HTML (0) PDF 566.68 K (671) Comment (0) Favorites

      Abstract:The concept and method of fuzzy sets were proposed only more than ten years ago.And they have been used in many scientific fields nowadays.
      The authors try to introduce the knowledge of fuzzy mathematics into earthquake prediction. Therefore, "normality" and "abnormality" are preliminarily explored by using fuzzy language. The membership functions of the single precursor abnormality and multiple precursor abnormality are preliminarily determined, the method of programming the earthquake prediction is boldly imagined and internally examined by using two simple cases as samples, and finally, some preliminary results are obtained. It is considered that the prospect for using the technique of fuzzy mathematics is captivating.

    • THE STUDY OF THE ELECTROMAGNETIC WAVES INFORMATION DURING THE APPROACHING OF THE EARTHQUAKES

      1981, 3(3):9-14.

      Abstract (499) HTML (0) PDF 487.59 K (690) Comment (0) Favorites

      Abstract:During the period before and after the earthquake of magnitude 6.0 occurred on July 9, 1979 in Liyang, Jiangsu province, the observational station of electromagnetic waves in Nanjing(epicenter distance about 80 km)indicated the following three types of waves:
      1. The electromagnetic, waves arising at the early stage before the earthquake are called waves type A;
      2. The electromagnetic waves arising in the form of wave train before the approaching of the earthquake are called waves type B;
      3. The electromagnetic waves arising after the earthquake characterizing both A and B are called waves type AB.
      All sorts of the phenomena indicated that the characteristics of the electromagnetic waves arising during the approaching of the earthquake are:the nearer the occurrence of the earthquake approached, the higher the frequency of the electromagnetic waves. Moreover, the frequency spectrum of the electromagnetic wave sappeared to be wider than it is known today. In the continued duration in which the electromagnetic waves were arising, the group number of the wave train reached the peak value.

    • GRAVITY ANOMALY OF TANGSHAN EARTHQUAKE

      1981, 3(3):15-20.

      Abstract (573) HTML (0) PDF 384.44 K (498) Comment (0) Favorites

      Abstract:The practice and experiments for many years have proved that the calibration of the gravimeter varies with temperature and has great effect on observed values. So it is necessary to find the temperature coefficent of the calibration and to correct the calibration of the observation data.
      In this article, the calibration of all gravity data in Beijing, Tianjin and Tangshan regions has been corrected in another way. After the correction, the annual variation of gravity values at various stations is obviously eliminated, and has been calculated pre-earthquake gravity anomaly in Tangshan.
      From April, 1974 to March, 1976, the cumulative gravity increased by 130μgal and the short-term anomaly approached 200μgal.
      The obtained results show that. the pre-earthquake gravity variation may due to the density anomaly at deep levels of the earth's crust.

    • AN ENERGY NOTATION TO DISTINGUISH SUCCESSIVE STRONG EARTHQUAKES

      1981, 3(3):21-26.

      Abstract (562) HTML (0) PDF 422.76 K (621) Comment (0) Favorites

      Abstract:In the activity of a seismic sequence, there is often a destructive earthquake after the swarm.It is difficult to say that they belong to the same sequence, but it is possible that they are related each other in mechanism.In this paper, we discuss it from the energy idea. It shows that the volume and the area of the aftershock are related to the energy of the major earthquake.when the released energy is only a little part of the strain energy, then the remained energy is corresponding to the forthcoming strong earthquake.

    • TRAVEL TIME OF P-WAVE AND UPPER MANTLE STRUCTURE IN THE QINGHAI-XIZANG PLATEAU REGION

      1981, 3(3):27-34.

      Abstract (508) HTML (0) PDF 536.64 K (545) Comment (0) Favorites

      Abstract:Using the data of natural earthquakes, we have studied the characteristics of P-wave travel time in Qinghai-Xizang plateau and its vicinity. From 2° to 26°, travel time of p-wave could be approximately described by three sections of straight line, there are remarkable changes for apparent velocities near 10 and 19° Inferred upper mantle structure shows:
      (1)The P-wave velocity in the uppermost part of the mantle beneath the plateau is 8.11±0.04 km/sec;
      (2)In the Tengchong(腾冲)district, there exists a low-velocity layer with a p-wave velocity of 7.59±0.09km/sec. The depth of the low velocity layer is between 40km and 170km;
      (3)The depth of "20° discontinuity" is 450-500km, and the P wave velocity beneath it is about 9.9km/sec;
      (4)P-wave velocities increase, with depth from Moho towards "20± discontinuity".
      Besides, we have discussed the tectonophysical implications of the results in this paper.

    • EARTH-RESISTIVITY, GEOMAGNETIC ANOMALIES AND GROUND SURFACE SUBSIDENCE AND SYNCLINAL BENDING OF THE UPPER CRUST PRIOR TO THE 1976 TANGSHAN EARTHQUAKE

      1981, 3(3):35-42.

      Abstract (502) HTML (0) PDF 634.42 K (730) Comment (0) Favorites

      Abstract:Prior to the M7.8 Tangshan earthquake of 1976, earth-resistivity caused by crustal strain and geomagnetism △Z=Za-Zb showed anomalies over large areas of essentially coinciding geographic extent. According to experiments on the change of electric resistivity of rock (or earth)under artificial compression in situation, it is inferred that the regional decrease of earth-resistivity observed during the period of 1973-1976 was caused by the compaction of the upper layers of the crust near ground surface, amounting to a linear strain of about 3×10-5.It is interesting to note that △Z was also observed to decrease during the period of 1975-1976. As compared with changes in △Z, the variation △F of the total magnetic intensity is smaller, showing that the magnetic dip Ⅰ also decreases. From the fact that magnetic bodies are buried rather deep as evidenced by aeromagnetic surveys, and from the results of experiments, on cemanent magnetization for samples stressed, it is inferred that the changes in △Z and △I are caused by inelastic expansion of magnetic bodies burred 8-25-km deep. The precision levelling over the epicentral area prior to the Tangshan earthquake showed that the ground surface had been subsiding since 1969. According to the mean sea-level at Qinhuangdao the subsidence of the land continued till the occurrence of the Tangshan Earthquake, being greatest near Ninghe (epicentral distance=50 kin)amounting to 82-12 cm.
      By synthesizing the phenomena of ground surface subsidence, compression of the upper layers and expansion of the deep layers, a mechanical model is proposed:The upper crust (0-25km) of the epicentral Zone of the Tangshan earthquake underwent a synclinal bending(a kind of active folding). The occurrence of the Tangshan earthquake might be caused by continued accumulation of the bending strain of the syneline which resulted in fracturing or fault plane sliding. By this model the controversy between the source mechanism of the Tangshan earthquake and the mechanics of the Neocathaysian system can be explained.

    • A PHYSICAL EXPLANATION OF ANNUAL VARIATION OF EARTH RESISTIVITY-OBSERVATIONS AT DABOSHE STATION OF EARTH RESISTIVITY

      1981, 3(3):43-47.

      Abstract (511) HTML (0) PDF 386.73 K (673) Comment (0) Favorites

      Abstract:Through corelation analysis and mathematical model computation of the observed data of earth resistivity with different electrode spacing carried out at Daboshe Station, Longyao County of Hebei province, a physical explanation of the annual variation of earth resistivity is proposed. It is highly probable that the annual variation of earth resistivity is caused by the effect of change in ground water level resulting from the close electrode spacing used. To avoid such interference, the electrodes should be spaced at least 500 meters from one another (the overall dimension should be at least 1500 meters) at Daboshe Station.

    • NUMERICAL ANALYSIS OF HEAT INCREASE IN THE LOWER ATMOSPHERE PRIOR TO THE HAI-CHENG EARTHQUAKE (1975)

      1981, 3(3):48-60.

      Abstract (628) HTML (0) PDF 882.06 K (1193) Comment (0) Favorites

      Abstract:This paper deals with the cause-of heat increase in the lower atmosphere in Hai-Cheng region prior to the earthpuake.
      By means of the temperature tendency equation, each item of heating factors has been Considered. The vertical velocity item's (convection item) value was -8.6℃/day, -3.8℃/day, on 3rd and Feb, respectively in the 1000rob to 970mb level, The radiation item's value was 3.9℃/day, 3.3℃/day on 3rd and 4th Feb. respectively, The horizotal transport item's value was 0.43/day, -0.8℃/day on 3rd and 4th. Feb. respectively. The latent heat item's value was Very small. The Sensible heat value (flux of sensible heat at atmosphere bottom), was calculated from the temperature tendency equation inversely; it seemed to be 7.4℃/day, 3.8℃/day on 3rd and 4th respectively. But the odeservations of the mean air temperture at 1.5m height in Hai-Cheng region showed that it appeared above the average ground temperature during the half period of lst-4th. Feb. It hinted that during the half period the sensible heat was transported from atmosphere to t-he ground. The net sensible heat transport was near zeros.
      The result shows that the heating mode of the lower atmosphere prior to the earthquake is Very different from traditional heating (conduct, eddy transport) It may be concerned with the pollution of gases which overflowed out of ground prior to the earthquake.

    • CHARACTERISTICS OF DEFORMATION BAND OF THE 1937 TUOSUOHU EARTHQUAKE (M=7.5) IN QINGHAI

      1981, 3(3):61-65.

      Abstract (928) HTML (0) PDF 405.07 K (766) Comment (0) Favorites

      Abstract:The deformation band of Tuosuohu earthquake Jan. 7, 1937(M=7.5) was 300km long. Strike as a whole was N70°W, in keeping with Kusaihu and Maqu fracture zone. This deformation band consists of a series of fault scarps, little upheavals, tension fissures, fault ridges and small segs. The combination of all deformation phenomena has shown that earthquake fracture is compressional with anticlockwise torsion characteristics and that the direction of compressional stress of earthquake region stress field is NEE-SWW. The structure of upheavals and segs of NNW direction, has intersected with the fracture Kuma in the earthquake region. The said structure has impeded the anticlockwise torsion of the fracture Kuma. Stresses have been congregated here. That was the essential cause which led to the occurrence of this strong earthquake.

    • THE FAILURE AND THE EVALUATION OF THE STABILITY OF ARTIFICIAL ROCK SLOPE OF CUT IN MACROSEISMIC AREA

      1981, 3(3):66-72.

      Abstract (530) HTML (0) PDF 530.08 K (961) Comment (0) Favorites

      Abstract:The failure of artificial rock slope of cut in macroseismic area always causes enormous damage. From the data of various macroscopic earthquake damages in Tonghai, Zhaotong earthquake areas (Yunnan Provirice) and Haicheng earthquake area (Liaoning Province) and from the point of view of engineering seismogeology, the structure of rock mass, the spatial combinatory relationship between the structure surface of rock mass and the slope orientation, and the effect of seismic intensity on the stability of the slope of cut are discussed in this paper. In addition, some ideas with practical engineering significance are presented for reference.

    • THE PRE-PROCESSING METHOD OF THE OBSERVATION DATA OF EARTH TIDES

      1981, 3(3):73-77.

      Abstract (525) HTML (0) PDF 351.45 K (835) Comment (0) Favorites

      Abstract:This paper deals with the theory and application of the pre-processing method in the harmonic analisis of earth tides. Before using the Venedikov filters, we applied two step error detection to observation data. Forst, the data was smoothed by means of several filters. Then the occidental fault data, jump data or bad reading among the observation data were corrected, and thus the reading errors of observation, data were not more than 1 mm. Secondly, a rough least square adjustment was made on each 48 hour interval, that would be covered by a Venedikov filter {Nakai, 1975}. Then the bad groups of 48 hour interval could be detected out and a smoothing scale for each group could be given. By adopting this method the bad groups caused by anomalous drift in a short time (for example, 3-5 hours) might be corrected. Finally, the rest of bad groups, should be discarded in the computation of final results. Through the two step error detection, the accuracy of the computational results was promoted.

    • TYPE WL 3 CURRENT STABILIZED D. C POWER SUPPLY

      1981, 3(3):78-84.

      Abstract (483) HTML (0) PDF 471.23 K (638) Comment (0) Favorites

      Abstract:During recent years a number of current stabilized D. C power supplies have been designed for earth resisivity measurement in the research of earthquake prediction. Type WL3 current stabilizer is the newest of them to supply power of up to 2.5KW at 5A to non-inductive load.
      The design and basic theory of WL3 current stabilizer are discussed by means of SCR for current control component, and the circuit of WL3 current stabilizer is described. Its current stability against load resistance variations or changes in three phase mains voltage is better than 1 per cent. With an initial load resistance of 100, the measured current stability at 5A is 0.9 per cent for 50 per cent reduction in load resistance and 0.8 per cent for 30 per cent change in mains voitage.
      The question of critical inductance is also discussed.
      It is suitable for geoelectric stations which have three phase mains in our country.

    • CAUSES OF THE VARIATIONS OF GREAT AMPLITUDE OF VELOCITY RATIO OF SEISMIC WAVES IN THE LIN-YI DISTRICT OF SHANDONG PROVINCE

      1981, 3(3):85-89.

      Abstract (521) HTML (0) PDF 292.39 K (391) Comment (0) Favorites

      Abstract:许多地震工作者对地震波速的大量研究工作,已证实了在大地震发生之前,孕震区内及其周围地区,可能会出现地震波速度或波速比的下降异常。例如海域、松潘、新丰江、宁蒗等地震,震前都出现过波速比的异常变化[1、3-6]

    • CHARACTERISTICS OF HISTORICAL EARTHQUAKE ACTIVITIES IN GANSU

      1981, 3(3):90-91.

      Abstract (497) HTML (0) PDF 133.96 K (749) Comment (0) Favorites

      Abstract:无论从地震活动的强度,还是频度看,河西走廊地区都可以说是我国地震比较活动的地区之一,故素称"河西走廊地震带"。据统计,从公元180年秋,高台附近的7.5级地震以来,河西地区发生过的破坏性地震(Ms ≥ 5)就达30多次(见《中国地震目录》一至四册),其中20多次发生在1900年以后的这七十来年间。

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