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DONG SONGSHENGup, HUANG CAIZHONGup2, LIN MINGZHOUup3, ZHOU BAOZHENGup, SUN QINGXUANup3, ZHU HAILINup2, LU ZHENPEIup. 1982: PRECURSORY VELOCITY VARIATIONS BY ARTIFICIAL WAVE SOURCES-TEMPORAL CHANGES OF APPARENT VELOCITY-RATIO PRIOR TO THE LIYANG JIANGSU EARTHQUAKE OF JULY 9, 1979. Acta Seismologica Sinica, 4(1): 1-13.
Citation: DONG SONGSHENGup, HUANG CAIZHONGup2, LIN MINGZHOUup3, ZHOU BAOZHENGup, SUN QINGXUANup3, ZHU HAILINup2, LU ZHENPEIup. 1982: PRECURSORY VELOCITY VARIATIONS BY ARTIFICIAL WAVE SOURCES-TEMPORAL CHANGES OF APPARENT VELOCITY-RATIO PRIOR TO THE LIYANG JIANGSU EARTHQUAKE OF JULY 9, 1979. Acta Seismologica Sinica, 4(1): 1-13.
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PRECURSORY VELOCITY VARIATIONS BY ARTIFICIAL WAVE SOURCES-TEMPORAL CHANGES OF APPARENT VELOCITY-RATIO PRIOR TO THE LIYANG JIANGSU EARTHQUAKE OF JULY 9, 1979

  • 1. Seismological Bureau of Jiangsu Province; 2. Liyang Seismic Station; 3. Seismological Bureau of Shanghai

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  • Published Date: August 31, 2011
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    • Abstract
  • Kelation between apparent velocity-ratio =ts11-ts/tp11-tpand real velocity-ratio of thecrustal medium has been discussed in the present paper. Theoretical values of the apparent velocity-ratio have been calculated supposing that the crust consists of two horizontal layers and that within the upper layer of the crust there exists a zone of anomalous seismic velocity, upper and lower boundaries of which are horizontal. The results obtained indicate that in certain cases the anomaly fails to be detected by horizontally propagating direct waves (as, for example, direct waves do not pass through the anomalous zone, or the horizontal extent of the anomalous zone is rather small and so on). However, on the basis of variations of values it is still possible to be detected if the reflected waves pass through the anomalous zone.Seismic data recorded by seismic station at Liyang, Jiangsu from explosions at Maanshan Iron Mine have been studied using the above mentioned method. Negative anomaly of values is detected prior to the Liyang, Jiangsu earthquake (July 9, 1979, Ms =6.0). Average amplitude and duration of the anomaly are 5% and 15-17 months respectively. The anomaly could well be explained, if the path length of the direct waves within the anomalous zone is rather small, or they do not pass through the anomalous zone at all.The present paper indicates that by means of artificial wave sources in detecting precursory variations of seismic wave velocities the results might be improved, if reflected waves are used.
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    • References (1)
  • [1] Y. P. Aggarwal et al., Spatial and temporal variations in ts/tp and in P wave residuals at Blue Mountain Lake, New York: Application to earthquake prediction, J. Geophys. Res., 80, 5, 718——732, 1975.

    [2] C. H. Cramer et al., P wave travel time variations before the August 1, 1975 Oroville, California earthquake, Bull. Seism.. Soc. d7n., 67, 1, 9——26, 1977.

    [3] T. Utea, Temporal variations in travel time residuals of P wave from Nevada sources, J. Phys.Earth, 2 1, 4, 475——480, 1973.

    [4] N. A, Dolbilkina et al., The study of time variations of elastic——wave parameters: results and problems, Phys. Earth and Planetary Interiors, 8, 4, 319——325, 1979.

    [5] T. V. McEvilly and L. R. Johnson, Stability of P and S velocities from central California quarry blasts, Bull. S'eis7n.. Soc. fan., 64, 2, 343——353, 1974.

    [6] 冯锐等,海城地震前后地震波速比的变化,地球物理学报,19, 4, 295——305, 1976.

    [7] Dung Sung——sheng of al., Earthquake prediction on the basis of Yp/Vs variations——a case history,Phys. of the Earth and Planetary Interiors, 18, 4, 309——318, 1979.

    [8] 姜秀娥,陈非比,用单台四震相法讨论唐山大震的波速异常,地球物理学报,24, 1, 107——116, 1981,

    [9] 曾融生、宋子安,我国境内瑞利波的相速度,地球物理学报,12, 2, 148——165, 1963,

    [10] 曾融生,莫霍界面的重力补偿和地壳结构的基本模式,地球物理学报,16, 1——5, 1973,

    [11] B.古登堡著,王子昌译,傅承义校,地球内部物理学,科学出版社,32——35, 1965,

    [12] 力武常次著,冯锐、周新华译,地震预报,地震出版社,192, 1978,

    [13] 冯德益等,我国西部地区一些强震及中强震前后波速异常的初步研究(二)—波速异常区及其特性,地球物理学报,20,2,115——123,1977.

    [1] Y. P. Aggarwal et al., Spatial and temporal variations in ts/tp and in P wave residuals at Blue Mountain Lake, New York: Application to earthquake prediction, J. Geophys. Res., 80, 5, 718——732, 1975.

    [2] C. H. Cramer et al., P wave travel time variations before the August 1, 1975 Oroville, California earthquake, Bull. Seism.. Soc. d7n., 67, 1, 9——26, 1977.

    [3] T. Utea, Temporal variations in travel time residuals of P wave from Nevada sources, J. Phys.Earth, 2 1, 4, 475——480, 1973.

    [4] N. A, Dolbilkina et al., The study of time variations of elastic——wave parameters: results and problems, Phys. Earth and Planetary Interiors, 8, 4, 319——325, 1979.

    [5] T. V. McEvilly and L. R. Johnson, Stability of P and S velocities from central California quarry blasts, Bull. S'eis7n.. Soc. fan., 64, 2, 343——353, 1974.

    [6] 冯锐等,海城地震前后地震波速比的变化,地球物理学报,19, 4, 295——305, 1976.

    [7] Dung Sung——sheng of al., Earthquake prediction on the basis of Yp/Vs variations——a case history,Phys. of the Earth and Planetary Interiors, 18, 4, 309——318, 1979.

    [8] 姜秀娥,陈非比,用单台四震相法讨论唐山大震的波速异常,地球物理学报,24, 1, 107——116, 1981,

    [9] 曾融生、宋子安,我国境内瑞利波的相速度,地球物理学报,12, 2, 148——165, 1963,

    [10] 曾融生,莫霍界面的重力补偿和地壳结构的基本模式,地球物理学报,16, 1——5, 1973,

    [11] B.古登堡著,王子昌译,傅承义校,地球内部物理学,科学出版社,32——35, 1965,

    [12] 力武常次著,冯锐、周新华译,地震预报,地震出版社,192, 1978,

    [13] 冯德益等,我国西部地区一些强震及中强震前后波速异常的初步研究(二)—波速异常区及其特性,地球物理学报,20,2,115——123,1977.
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