体波震级综合起算函数的研究
STUDY OF THE SYNTHETIC CALIBRATION FUNCTION OF BODY WAVE MAGNITUDE
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摘要: 为了改进中国地震台网体波震级的测定工作,本文利用中国地区地震P波和S波走时表及其相应的地壳地幔速度模型和地球的吸收带Q值模型(简称ABM-Q值模型),讨论了地震波的几何扩散效应和地球介质的吸收效应;通过数值计算,制定了中国地震台网体波震级的综合起算函数。经初步使用检验表明,新的震级起算函数,由于引进了与周期相对应的补偿,使得所测不同周期的体波震级基本趋向一致,改善了Gutenberg和Richter(1956)的起算函数在短周期上低估震级的倾向;而且,ABM-Q值模型较之SL8-Q值模型更加符合体波的衰减特性。Abstract: The synthetic calibration functions of body-wave magnitude for Chinese stations are formulated in terms of P and 8 wave travel times from earthquakes in the Chinese region and its corresponding velocity distribution model in the crust and mantle and absorption band Q model for the earth (abbreviated ABM-Q model), discussing the effects of geometrical spreading of seismic waves and absorption by the medium in the earth. The results obtained demonstrate:(1)A factor T1-a in the synthetic calibration function is introduced through the frequency-dependence of quality factor Q. That isf(△, h, T) = g(△, h) + a(△, h)/T1-aWhere the parameter a characterizes the degree of frequency-dependence of the quality factor Q in the ABM-Q model, but here it represents the period-dependence of the calibration functions. This is a theoretical improvement on the calibration functions of Gutenberg and Riehter (1956) and of Nortmann and Duda (1982).(2)The term a (A, h) characterizing effect of absorption has higher compensation obviously in the upper mantle and the bottom mantle in the new calibration functions, in comparison with Nortmann and Dudas (1982). This is consistent, so far as known with the tendency of Q distribution with depth.(3)The tendency of underestimating magnitude by Gutenberg and Riehter (1956) calibration functions in the short period range and by Nortmann and Duda (1982) calibration function in the long period range is improved in the preliminary practical tests, so that the magnitudes determinated from different seismic wave periods are basically consistent.(4)The new calibration functions can be used as basic data in formulating the calibration function of body-wave spectral magnitude.
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[1] Abe, K., Magnitudes of Iarge shallow earthquakes from 1904——1980, Phys. Earth Planet. Inter,271, 72——92, 1981.
[2] Abe, K. and S. Noguchi, Determination of magnitude for large shallow earthquakes 1898——1917,Phys. Earth Planet. Inter., 32, 1, 45——59, 1983.
[3] Kanamori, H., Magnitude scale and quantification of earthquakes, Tectonophysics, 93, 185——199,1983.
[4] Purcaru, G. and H. Berckhemer, Quantitative relations of seismic source parameters and a classification of earthquakes, Tectonophysics, 84, 1, 57——128, 1982.
[5] Purcaru, G., S. J. Dada, and H. Berckhemer, Earthquake classification using spectral magnitudes,引自1983年德国汉堡IUGG第18届会议(待发表).
[6] Dada, ,. J.,震级与地震定量化,地震地磁观测与研究,阎志德、左兆荣译,4, 9, 69 92,1983
[7] Gutenberg, B. and C. F. Richter, Magnitude and energy of earthquakes, Ann. di Geofss. (Rome),9, 1——15, 1956.
[8] Miyamura, S., Considerations for the body——wave magnitude determination in the recent EarthquakeData Report of the United States Geological Survey, Tectonophysics, 93, 313——318, 1983.
[9] Duda, S. J., TtaveI time and body wave magnitude, Pure Appl. Geophys. 87, 13——37, 1971.
[10] 左兆荣、郭履灿、许忠淮,地震波的几何扩故效应,地震地磁观测与研究,4, 52——63,1983.
[11] Solovieva, O. N., Determination of magnitude of deep——focus earthquakes, Izvestiya AN SSSR, Ser.Fixika Zemli, 1, Moscow, 25——35, 1978.
[12] Christoskov, L., et al., Homogeneous magnitude system of the Eurasian continent, Tectonophysics,49, 131——138, 1978.
[13] Veith, K. F. and G. E. Clawson, Magnitude from short——period P——wave data, BSSA, 62, 435————452.1972.
[14] Nortmann, R. and S. J. Duda, The amplitude spectra of P——and S——wave and the body——wave magnitude of earthquakes, Tectonophysics, 84, 17——32, 1982.
[15] Nortmann, R. and S. J. Duda, Determination of spectral properties of earthquakes from their magnitudes, Tectonophysics, 93, 251——275, 1983.
[16] Anderson, D. L., and R. S. Hart, Q of the Earth, J. Geophys. Res., 83 5869——5882, 1978.
[17] 郭友梅,阎志德等,中国地区地震P波和s波走时丧,地震学报,3, 197——209, 1951.
[18] 阎志德,郭履灿,唐友梅,中国地区地震P波和S波走时表灼实用检验,西北地震学报,3, 13——17,1981,
[19] Minster, J. B. and D. L. Anderson, A model of dislocation——controlled rheology for the mantle,Phil. Tra,as. R. Soc. Lond. A, 299, 319——356, 1981.
[20] Gordon, R. B. and C. D,. Nelson, Anelastic properties of the earth, Rev. Geophys.,457——474.1966.
[21] Anderson, D. L., and R. S. Hart, Attenuation models of the earth, PF,ys. Earth Plaaet. Inter., 16,289——306, 1978.
[22] Dziewonski, A. VI. and D. L. Anderson, Preliminary reference earth model, Phys. Earth Planet. Inter., 25, 297——356, 1981.
[23] Der, Z. A., et al., An investigation of the regional variations and frequency dependence of anelastic attenuation in the mantle under the United States in the O.S——4Hz band, Geophys. J. R. astr. Soc.,69, 1, 67——100, 1982.
[24] CIements, J. R., Intrinsic Q and its frequency dependence, Pfzys. Earth Planet. Inter., 27, 3, 286——299, 1982.
[25] Anderson, D. L. and J. W., Given, Absorption band Q model for the earth, J. Geophys. Res.,87, 3893——3904, 1982.
[26] Bullen, K. E., An Introduction to the Theory of Seismology, Cambridge University Press, London,1963.[1] Abe, K., Magnitudes of Iarge shallow earthquakes from 1904——1980, Phys. Earth Planet. Inter,271, 72——92, 1981.
[2] Abe, K. and S. Noguchi, Determination of magnitude for large shallow earthquakes 1898——1917,Phys. Earth Planet. Inter., 32, 1, 45——59, 1983.
[3] Kanamori, H., Magnitude scale and quantification of earthquakes, Tectonophysics, 93, 185——199,1983.
[4] Purcaru, G. and H. Berckhemer, Quantitative relations of seismic source parameters and a classification of earthquakes, Tectonophysics, 84, 1, 57——128, 1982.
[5] Purcaru, G., S. J. Dada, and H. Berckhemer, Earthquake classification using spectral magnitudes,引自1983年德国汉堡IUGG第18届会议(待发表).
[6] Dada, ,. J.,震级与地震定量化,地震地磁观测与研究,阎志德、左兆荣译,4, 9, 69 92,1983
[7] Gutenberg, B. and C. F. Richter, Magnitude and energy of earthquakes, Ann. di Geofss. (Rome),9, 1——15, 1956.
[8] Miyamura, S., Considerations for the body——wave magnitude determination in the recent EarthquakeData Report of the United States Geological Survey, Tectonophysics, 93, 313——318, 1983.
[9] Duda, S. J., TtaveI time and body wave magnitude, Pure Appl. Geophys. 87, 13——37, 1971.
[10] 左兆荣、郭履灿、许忠淮,地震波的几何扩故效应,地震地磁观测与研究,4, 52——63,1983.
[11] Solovieva, O. N., Determination of magnitude of deep——focus earthquakes, Izvestiya AN SSSR, Ser.Fixika Zemli, 1, Moscow, 25——35, 1978.
[12] Christoskov, L., et al., Homogeneous magnitude system of the Eurasian continent, Tectonophysics,49, 131——138, 1978.
[13] Veith, K. F. and G. E. Clawson, Magnitude from short——period P——wave data, BSSA, 62, 435————452.1972.
[14] Nortmann, R. and S. J. Duda, The amplitude spectra of P——and S——wave and the body——wave magnitude of earthquakes, Tectonophysics, 84, 17——32, 1982.
[15] Nortmann, R. and S. J. Duda, Determination of spectral properties of earthquakes from their magnitudes, Tectonophysics, 93, 251——275, 1983.
[16] Anderson, D. L., and R. S. Hart, Q of the Earth, J. Geophys. Res., 83 5869——5882, 1978.
[17] 郭友梅,阎志德等,中国地区地震P波和s波走时丧,地震学报,3, 197——209, 1951.
[18] 阎志德,郭履灿,唐友梅,中国地区地震P波和S波走时表灼实用检验,西北地震学报,3, 13——17,1981,
[19] Minster, J. B. and D. L. Anderson, A model of dislocation——controlled rheology for the mantle,Phil. Tra,as. R. Soc. Lond. A, 299, 319——356, 1981.
[20] Gordon, R. B. and C. D,. Nelson, Anelastic properties of the earth, Rev. Geophys.,457——474.1966.
[21] Anderson, D. L., and R. S. Hart, Attenuation models of the earth, PF,ys. Earth Plaaet. Inter., 16,289——306, 1978.
[22] Dziewonski, A. VI. and D. L. Anderson, Preliminary reference earth model, Phys. Earth Planet. Inter., 25, 297——356, 1981.
[23] Der, Z. A., et al., An investigation of the regional variations and frequency dependence of anelastic attenuation in the mantle under the United States in the O.S——4Hz band, Geophys. J. R. astr. Soc.,69, 1, 67——100, 1982.
[24] CIements, J. R., Intrinsic Q and its frequency dependence, Pfzys. Earth Planet. Inter., 27, 3, 286——299, 1982.
[25] Anderson, D. L. and J. W., Given, Absorption band Q model for the earth, J. Geophys. Res.,87, 3893——3904, 1982.
[26] Bullen, K. E., An Introduction to the Theory of Seismology, Cambridge University Press, London,1963.
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