Department of Mathematics and Physics, University of Campania "L. Vanvitelli," 81100 Caserta, Italy.
Department of Industrial and Information Engineering, University of Campania "L. Vanvitelli," 81031 Aversa (CE), Italy.
Phys Rev E. 2018 Jan;97(1-1):010901. doi: 10.1103/PhysRevE.97.010901.
According to the acoustic fluidization hypothesis, elastic waves at a characteristic frequency form inside seismic faults even in the absence of an external perturbation. These waves are able to generate a normal stress which contrasts the confining pressure and promotes failure. Here, we study the mechanisms responsible for this wave activation via numerical simulations of a granular fault model. We observe the particles belonging to the percolating backbone, which sustains the stress, to perform synchronized oscillations over ellipticlike trajectories in the fault plane. These oscillations occur at the characteristic frequency of acoustic fluidization. As the applied shear stress increases, these oscillations become perpendicular to the fault plane just before the system fails, opposing the confining pressure, consistently with the acoustic fluidization scenario. The same change of orientation can be induced by external perturbations at the acoustic fluidization frequency.
根据声流假设，即使没有外部扰动，地震断层内部也会形成具有特征频率的弹性波。这些波能够产生一个法向应力，与围压相反，从而促进破坏。在这里，我们通过对颗粒断层模型的数值模拟来研究这种波激活的机制。我们观察到属于维持应力的渗透骨架的颗粒，在断层平面上沿椭圆形轨迹进行同步振荡。这些振荡发生在声流的特征频率。随着施加的剪切应力增加，这些振荡在系统失效之前变得垂直于断层平面，与围压相反，这与声流化情景一致。在声流化频率下，外部扰动也可以产生相同的取向变化。
