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报告了正断层破裂的泡沫橡胶模型中质点运动的测量结果,并且与走滑断层的结果进行了对比。一般情况下,正断层地震的强地面运动的标准计算机模拟是使用位错理论。在位错理论中,假设断层滑动遵从某些特殊的时间函数,并用此描述了沿断层浅层部分的滑动。遗憾的是,对正断层来说,基本上没有大地震的断层附近的资料来制约断层模型。在张断裂方式下,沿断层的有效正应力与剪应力在地表接近于零,这样,断层近地表的几公里所积蓄的应变能就比走滑断层可能积累的最大应变能要小。另外,还有几何因素所产生的动力学效应和存在影响断层运动的断层正应力降。断层的物理模型,如泡沫橡胶模型必须保证满足静态的和动态的力学定理,才能用来研究所涉及的物理过程。在本研究中,我们对正断层模式与走滑断层模式的地表加速度进行了对比,结果表明,正断层迹线附近的地表加速度系统地偏低,与模型两侧传感器测得的加速度,即走滑断层的地表加速度相比,平均比例因子约为0.1。这些结果表明,用传统的位错技术对地面运动的运动学模拟对于断层的浅层是不合适的。本研究结果与那些数值模型,诸如动力网格模型和有限元模型所得的结果定性上是一样的。实际的地球可能具有类似的效应。
The measurement of particle motion in the foam-rubber model of a normal fault rupture was reported and compared with the results of strike-slip faults. In general, the standard computer simulations of strong ground motions of normal-fault earthquakes use dislocation theory. In the theory of dislocations, it is assumed that fault slip follows some special time function and describes the slip along the shallow part of the fault. Unfortunately, for normal faulting, there is essentially no data near the fault of a large earthquake to constrain the fault model. In Zhang fracture mode, the effective normal stress and shear stress along the fault are close to zero at the earth’s surface, so that the strain energy accumulated over a few kilometers near the fault surface is smaller than the maximum strain energy that the strike-slip fault may accumulate. In addition, there are geometric factors that produce the kinetic effect and the presence of faults that affect the normal fault movement. The physical model of the fault, such as the foam rubber model, must be guaranteed to satisfy both static and dynamic mechanical theorems in order to study the physical processes involved. In this study, we compared the surface acceleration of the normal fault mode with the strike-slip fault mode. The results show that the surface acceleration near the normal fault line is systematically low, and the acceleration measured by the sensors on both sides of the model Compared to the surface acceleration of the fault, the average scale factor is about 0.1. These results show that the kinematic simulation of ground motion using conventional dislocation techniques is not suitable for shallow faults. The results of this study are qualitatively the same as those obtained from numerical models such as the dynamic grid model and the finite element model. The actual Earth may have a similar effect.