地震前兆形变场研究
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摘要
假设在均匀弹性介质半空间中 ,存在一单一力源 →F ,通过求解弹性静力学方程 ,得到地球表面位移解 3个分量 (u、v,w )的解析表达式。讨论了理论垂直形变场的基本特征。力的大小是决定形变幅度的基本因素 ,力越大 ,形变幅度亦越大 ,反之 ,则越小。力源深度 h越大 ,形变幅度越小 ,影响范围越大 ,反之 ,形变幅度大 ,影响范围小。力源倾角为正时 (向下 ) ,形变中心区下降 ,倾角为负 (向上 )时 ,形变中心区隆起。力的方位角是决定形变场图像形态的重要因素。利用大同地区 (1 984～ 1 987年 )和张北地区 (1 984～ 1 991年 )水准测量资料反演这二个地区震前力学参数 ,结果表明 ,力源中心与实际震中位置相差小于 40 km,力的方位角近于水平 ,理论形变图与实测形变图基本相似
On the hypothesis that there is a single force →F in the homogeneously elastic half space, and through solving elastic statics equation, we got the analytic expression of the 3 components (u, v, w) of displacement solution on the surface of the earth. The basic character of the theoretic vertical deformation field is also discussed. The extent of deformation is directly proportional to the strength of the force, and is inversely proportional to the depth of the origin of the force. When the dip angle of the force is normal (downward), the central deformation area descends. In the contrary, the central deformation area rises. The dip angle is a main factor to decide the image shape of crustal deformation field. Using the leveling data of Datong region (1984～1987) and Zhangbei region (1984～1991) we inversed the dynamic parameters of the two region. The results show the difference between the center of the force system and the real epicenter is less than 40 km. Dip angle of force is nearly horizontal. Theoretical crustal deformation image is basically similar to the observed deformation image.
On the hypothesis that there is a single force →F in the homogeneously elastic half space, and through solving elastic statics equation, we got the analytic expression of the 3 components (u, v, w) of displacement solution on the surface of the earth. The basic character of the theoretic vertical deformation field is also discussed. The extent of deformation is directly proportional to the strength of the force, and is inversely proportional to the depth of the origin of the force. When the dip angle of the force is normal (downward), the central deformation area descends. In the contrary, the central deformation area rises. The dip angle is a main factor to decide the image shape of crustal deformation field. Using the leveling data of Datong region (1984～1987) and Zhangbei region (1984～1991) we inversed the dynamic parameters of the two region. The results show the difference between the center of the force system and the real epicenter is less than 40 km. Dip angle of force is nearly horizontal. Theoretical crustal deformation image is basically similar to the observed deformation image.
引文
[1 ] 罗灼礼 .震源应力场、形变场和倾斜场 [J].地震学报 ,1 980 ,2 (2 ) :1 69- 1 84.
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[3] Alekseev A S,Belonosov A S,Petrenko V E. A mathematical model of determining the stress fieldand dilatant zones by gcodetic data. Bull Nov Comp Center,Math Model,in Geoph,1 998,4:1 5- 2 1 .
[4] 朱传镇 ,王琳瑛 ,林邦慧 .大同 -阳高地震序列特征 [A].张国民 ,马丽 .大同 -阳高地震研究 [C].北京 :地震出版社 ,1 993.1 1 - 1 8.
[5] 张国民 .一九九八年张北地震 [M].北京 :地震出版社 ,1 999
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