Jamming and Unjamming: from Glasses to Earthquakes
|Research Area||Earth Sciences|
|Principal Investigator(s)||Massimo Pica Ciamarra|
Avalanches and earthquakes occur when a disordered solid assembly of particles fails: it becomes unable to sustain the stress it is subject to, and start flowing. This project aims at providing the first microscopic understanding of the failure process, a problem of paramount importance due to its geophysical implications.
The goal is to comprehend 1) if there are precursors to the failure process, 2) if the approaching of the failure process is revealed by the study of the response of the system to external perturbations, and 3) if the energy released in the next failure process (earthquake) can be estimated.
Previous numerical efforts have mainly focused on very simple SOC (self-organized criticality) models, which reproduces some statistical features of failure processes such as earthquakes, but that are too simple for the study of precursors, as drastically simplify the mechanical nature of the process. On the other hand, experiments have focused on real world faults.
In this project, the focus will be on system of intermediate complexity, which have been surprisingly neglected so-far, where a fault is modelled via the use of granular materials, and the system investigated via molecular dynamics simulations. Concepts like force chains, correlation functions, dynamical susceptibilities, dynamical heterogeneities, force networks, Hessian and others, which have proven to be useful to get a deeper understanding of the jamming and of the glass transition, will be used here to investigate the failure transition. For the first time, precursors will be ’actively’ searched, investigating the response of the system to external perturbations.