Arresting mechanism of earthquake faulting

地震断层的阻止机制

基本信息

批准号：
08640522
负责人：
YAMASHITA Teruo
金额：
$ 0.9万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08640522/
关键词：
fault boundary integral equation method rupture 亀裂相互作用

项目摘要

Geometrical complexity of earthquake faults will be a manifestation of mechanical inhomogeneities of the earth's crust. It will therefore be closely associated with the arresting mechanism of dynamic earthquake faulting. A detailed study was carried out on the relation between the complexity of earthquake faulting and the arresting mechanism of faulting.High-pressure fluids existing in a fault zone can promote an earthquake rupture. The effect of pore-fluids on the earthquake rupture, especially on the arresting of rupture, is also studied in this research project.We developed new numerical methods to simulate an arbitrary-shaped rupture on the basis of boundary integral equation methods (BIEM). One of the difficulties in such a BIEM treatment is the evaluation of hypersingular integrals. We first made a formulation from the regularization approach, and derived a set of non-hypersingular boundary integral equations, both elastodynamic and elastostatic, for the analysis of arbitrarily s … More haped 2-D cracks. We carried out the simulation of dynamic cracks with side-branches. The results of the simulations show that the stress concentration at the propagating tip of the main crack is lowered by the presence of the side-branches. This suggests that the branching of the crack plays an important role in the deceleration and arresting mechanism of earthquake rupturing.The method based on the regularization approach is somewhat complicated, so that we next developed a more efficient method taking finite parts of hypersingular integrals. Numerical simulation of unsteady dynamic propagation of arbitrarily shaped 2-D cracks will be easily carried out using this method.It is well known from field observations that a fault zone is generally regarded as fluid conduit. If an earthquake rupture takes place, non-linear mechanical interactions occur between the fault fluids and the rupture. Our analysis of the interactions showed that the fluids can a factor to arrest the earthquake rupture if there is a high inhomogeneiry in the distribution of the fluid in the fault zone. Less

地震断层的几何复杂性是地壳力学不均匀性的表现，因此与动力断层的止震机制密切相关，对地震断层的复杂性与止震的关系进行了详细的研究。断裂带中存在的高压流体可以促进地震破裂，本文还研究了孔隙流体对地震破裂的影响，特别是对破裂的抑制作用。我们在边界积分方程方法 (BIEM) 的基础上开发了新的数值方法来模拟任意形状的破裂，这种 BIEM 处理的困难之一是超奇异积分的评估。正则化方法，并导出了一组非超奇异边界积分方程，包括弹性动力学和弹性静力学，用于分析任意形状的二维裂纹我们进行了动态模拟。模拟结果表明，侧枝的存在降低了主裂纹扩展尖端的应力集中，这表明裂纹的枝化在减速中起着重要作用。基于正则化方法的方法有些复杂，因此我们接下来开发了一种采用有限部分超奇异积分的非定常动态传播的数值模拟方法。使用这种方法可以很容易地实现任意形状的二维裂缝。从现场观察可知，断层带通常被视为流体管道，如果发生地震破裂，断层流体之间会发生非线性机械相互作用。我们对相互作用的分析表明，如果断层带中的流体分布高度不均匀，则流体可以成为阻止地震破裂的因素。