地震空区与逼近地震(续)
SEISMIC GAPS AND IMMINENT EARTHQUAKES (CONTINUED)
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摘要: 本文在《地震空区与逼近地震》一文(以下简称上篇)的基础上,分析了1970——1980年间我国大陆上所有资料较完整的6.0级以上的地震,以及60年代的两次7级以上地震的震例.结果表明,上篇所得的关于背景空区、孕震空区及逼近地震的结论具有普遍意义.本文在大量资料的基础上,充实了上篇论文的内容,并重新计算了上篇所得的经验公式.本篇指出,判别孕震空区有三个标志:(1)随着孕震空区的形成,空区及邻近区域的地震应变释放应出现加速;(2)孕震空区内外地震频度比(N外+1)/(N内+1)在孕震空区的形成过程中应出现峰值;(3)在背景空区形成前,未来主震震源区内常常发生一些中等强度的早期前震.此外,本文发现在孕震空区形成的过程中,孕震空区及其邻近区域的地震所释放能量的1/3次方的和 sum;E1/3与孕震空区长轴的对数线性相关,所得经验公式可作为发生逼近地震的时间判据.最后本文讨论了孕震空区尺度的物理解释和逼近地震的成因.Abstract: On the basis of a previous paper of the same title earthquakes of Mge;6 occurred during the period 1970-1980 and two earthquakes of M 7 of the 1960 's on the main land of China, are analysed. It is shown that the conclusions reached about '' background gaps, preparatory gaps and imminent earthquakes in the previous paper have general significance and thus it substantiates the results of the previous paper. The empirical -formula has been recomputed.Three criteria are proposed for the identification of preparatory gaps: 1) Along with the formation of a preparation gap, the seismic strain release should be accelerated in the gap area and its vicinity; 2) The ratio of earthquake frequencyoutside and inside the gap (k=N(out)+1/N(in)+1 ) should reach a maximum value during theprocess of its formation; 3) Some moderate earthquakes in the form of early fore-shocks would occur in the forthcoming epicentral area before the formation of the background gap. Besides, it is found there is a linear relation between Sigma;E1/3 and logarithm of the longer axis of a preparatory gap, where E is the energy release in the preparatory gap and its neighbouring region. The empirical formula obtained can be used as a time criterion of the occurrence of the imminent earthquake. Finally, the physical mechanism of imminent earthquakes and the dimension of the area of preparatory gaps are discussed.
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[1] 陆远忠等,地震空区与逼近地震,地震学报,4, 4, 1982.
[2] 中国科学院数学研究所数理统计组,回归分析方法,科学出版社,1975.
[3] 刘正荣,早期前震与终止破裂点,地震战线,6, 1977.
[4] 坪川家恒,地壳变动の继续时间と地震力规模との关系について,测地学会志,15, 1969.
[5] C. H. Scholz, L. R. Sykes and Y. P. Aggarwal, Earthquake prediction: a physical basis, Science, 181,1973.
[6] T. Rikitake, Earthquake precursors, B. S. S. A., 65, 1975.
[7] J. H. Whitcomb, J. D. Garmany, D. L. Anderson, Earthquake prediction: Variation of seismic veloci——ties before the San Fernando Earthquake, Seience, 180, 4086, 1973.
[8] 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)——一波速异常区及其特性,地球物理学报,20, 2, 1977.
[9] J. R. Rice, Theoty of precursory processes in the inception of earthquake rupture, Gerlands Beitr. Geophysik, Leipzig 88, 2,,.91——127, 1979.
[10] 西南地震烈度队,强弱地震的时空强关系,地震战线,3, 1973.
[11] 吴开统等,海城地震序列的特征,地球物理学报,19, 2, 1976.
[12] 邓起东等,中国地震烈度区划图编制的原则和方法,地震学报,2, 1, 1980.
[13] 郭增建等,震源物理,地震出版社,1979,[1] 陆远忠等,地震空区与逼近地震,地震学报,4, 4, 1982.
[2] 中国科学院数学研究所数理统计组,回归分析方法,科学出版社,1975.
[3] 刘正荣,早期前震与终止破裂点,地震战线,6, 1977.
[4] 坪川家恒,地壳变动の继续时间と地震力规模との关系について,测地学会志,15, 1969.
[5] C. H. Scholz, L. R. Sykes and Y. P. Aggarwal, Earthquake prediction: a physical basis, Science, 181,1973.
[6] T. Rikitake, Earthquake precursors, B. S. S. A., 65, 1975.
[7] J. H. Whitcomb, J. D. Garmany, D. L. Anderson, Earthquake prediction: Variation of seismic veloci——ties before the San Fernando Earthquake, Seience, 180, 4086, 1973.
[8] 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)——一波速异常区及其特性,地球物理学报,20, 2, 1977.
[9] J. R. Rice, Theoty of precursory processes in the inception of earthquake rupture, Gerlands Beitr. Geophysik, Leipzig 88, 2,,.91——127, 1979.
[10] 西南地震烈度队,强弱地震的时空强关系,地震战线,3, 1973.
[11] 吴开统等,海城地震序列的特征,地球物理学报,19, 2, 1976.
[12] 邓起东等,中国地震烈度区划图编制的原则和方法,地震学报,2, 1, 1980.
[13] 郭增建等,震源物理,地震出版社,1979,
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