地震位移场和板内地震震源力学性质的讨论
ON THE EARTHQUAKE DISPLACEMENT FIELD AND MECHANICAL CHARACTER OF INTRAPLATE EARTHQUAKE SOURCES
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摘要: 本文推导了各类点源和线源（压性、张性、压扭性、张扭性、单力偶和双力偶）的理论地震位移场公式, 讨论了板内地震的震源力学性质.根据实测地震位移场、建筑物破坏和倒塌的优势方向等近场资料与理论结果对比, 作者认为, 1966年邢台地震震源机制符合于张性断裂的模型;1966年东川地震震源机制符合于压扭性断裂的模型.根据理论公式和实际位移资料, 给出了邢台地震的地震矩 M0为6.51026达因厘米, 应力降△为39巴.最后指出大地震的震源力学机制反映了该区域长期构造应力作用的状态, 认为双力偶（剪切位错）不一定是板内地震震源机制的最合适的、唯一的模型.Abstract: In this paper, the formulae for the theoretical earthquake displacement fields of all kinds of point and line sources (compressional, tensional, compressional and torsional, tensional and torsional, single-couple and doublecouple) are derived. The mechanical character of intraplate earthquake sources has been discussed. In comparing the observed earthquake displacement fields and some near field data such as the predominant directions of collapse of buildings with the results of theoretical computation, the present authors have the opinion that the sources mechanism of the Xingtai earthquake of 1966 accords with the model of a tensional fracture, while that of the Dongchuan earthquake of 1966 accords with the model of a compressional and torsional fracture. Based on the theoretical formulae and the actually observed displacement data, the seismic moment M0 and the stress drop △ of the Xingtai earthquake are given to be 6.51026 dynccm and 39 bars respectively.Finally, it is pointed out that the source mechanisms of great earthquakes can reflect the action of the tectonic stress in this region for a long time and the double-couple model (shear dislocation model) may not be the only suitable model for intraplate earthquake.
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[9] 高名修, 华北断块构造区的现代引张应力场, 地震地质, 1, 2, 1979.[1] 陈运泰等, 根据地面形变的观测研究19"年邢台地震的震源过程, 地球物理学报18, 3, 1915.
[2] 王椿铺等, 用地形变资料测定通海地震的地震断层参数, 地球物理学报, 21, 3, 1918.
[3] 时振粱, 建筑物的破坏和断层附近的地面运动, 地球物理学报, 21, 3, 19i8.
[4] 罗灼礼, 震源应力场, 形变场, 倾斜场, 地震学报, 2, 2, 1980.
[5] 国家地震局地震测量队, 19"年邢台地震的地形变, 地球物理学报, 18, 3, 1975.
[6] C. A. Whitten, Geodetic measurements in the Dixie Valley area, B. S. S. A., 47, 4, 1957.
[7] 国家地震局地震测量队, 几个大震的地壳形变, 地震战线, 3, 1975.
[8] 国家地震局地震测量队, 地震形变的主要特征和震源力学模型, 地震战线, 1, 1975.
[9] 高名修, 华北断块构造区的现代引张应力场, 地震地质, 1, 2, 1979.
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