渤海及其周围地区现代构造应力场特征

THE CHARACTERISTIC OF THE CONTEMPORARY TECTONIC STRESS FIELD IN THE BOHAI SEA AND THE PERIPHERAL AREA

利用地震震源机制解等资料,分析了渤海地区现代构造应力场特征。结果表明,本区应力场总体方向较华北地区稍向右偏转,力的作用方式以近水平和水平为主,主压应力显示一定斜向作用和局部垂向作用;以横贯渤海的两亚板块(黑龙江与华北)分界带—北西向构造带为界,南北两区应力场方向存在差异,地震破裂方式也存在相应差异,这种差异可能与两区的动力源方向不一致有关。主压应力轴方向在其总体稳定的背景上呈现时间尺度不同的波动变化,进一步研究这种波动的成因及规律,对地震预报及岩石圈动力学的研究均有实用意义。

By use of the data of focal-mechanism solutions,the characteristics of the contemporarytectonic stress field in the Bohai Sea area are analysed in the paper.The results show that theoverall orientation of the stress field in the area is a little deflected towards right in comparisonwith that in North China.The stress acts dominantly in the horizontal or near horizontal direc-tion,and the principal compressive stress shows a certain oblique action and local vertical ac-tion.Delimited by a north-west belt which is the boundary of the two subplates across theBohai Sea,there exists differences between the directions of stress fields on both sides and therupture styles display corresponding differences,which appears to be associated with the differ-ent directions of dynamic sources in the two areas.The direction of principal axis ofcompressive stress shows variation with different periods superimposed on the overall stablebackground.A furthur study of the origin and regularity of such variation will be of practicalsignificance in the researches of earthquake prediction and lithosphere dynamics.