by Giacco Ferdinando, de Arcangelis Lucilla, Pica Ciamarra Massimo, Lippiello Eugenio
Abstract:
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.
Reference:
Synchronized oscillations and acoustic fluidization in confined granular materials (Giacco Ferdinando, de Arcangelis Lucilla, Pica Ciamarra Massimo, Lippiello Eugenio), In PHYSICAL REVIEW. E, volume 97, 2018. (Articolo in rivista)
Bibtex Entry:
@article{nan18,
author = {Giacco Ferdinando, and de Arcangelis Lucilla, and Pica Ciamarra Massimo, and Lippiello Eugenio,},
pages = {5},
title = {Synchronized oscillations and acoustic fluidization in confined granular materials},
volume = {97},
note = {Articolo in rivista},
issn = {2470-0045},
journal = {PHYSICAL REVIEW. E},
year = {2018},
scopusId = {2-s2.0-85040191260},
abstract = {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.}
}