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本文讨论了(1)区域应力场和震源应力场随时间的变化,提出在前兆机制研究的模拟计算中,可将前者看作是定常的,而后者是随时间不断变化的;(2)地震危险区的判别,认为在应变梯度较高同时应力又较集中的区域附近可能易发生中强地震。 作者通过用Max well粘弹性模型对一含壁垒的走滑断层的应力、应变积累过程进行有限元模拟,探讨了震源体发震前形成高应力差和高应变梯度的原因和过程。主要结论是:即使区域应力场是定常的,由于断层内外物质力学性质的不均匀分布,中强震的危险区终将出现在壁垒处及断层端部;断层内软弱带上可能仅发生小震或蠕滑。
This paper discusses (1) the change of regional stress field and source stress field over time, and suggests that in the simulation calculation of precursor mechanism research, the former can be regarded as stationary while the latter is changing with time; (2) Earthquakes Judging from the danger zone, it is considered that moderately strong earthquakes may occur easily in areas with higher strain gradients and more concentrated stress. By using Maxwell’s viscoelastic model, the stress and strain accumulation process of a barrier-containing strike-slip fault is simulated by finite element method. The reason and process of forming high stress difference and high strain gradient before earthquake occurrence are discussed. The main conclusion is that even though the regional stress field is constant, the danger zone of moderately strong earthquakes will eventually appear at the barriers and the ends of the faults due to the non-uniform distribution of the mechanical properties of the material inside and outside the fault. Only small earthquakes may occur in the weak zones within the fault Or creeping.