Modelling the Micro-physics Underlying Earthquake Nucleation Processes and Rupture

Objectives Modelling microscopic properties of rock allows simulation of non-linear and complex macroscopic behaviour. Rather than specifying a "true" representation of rock at a microscopic scale, models use empirical properties at a mesoscopic scale such that the correct macroscopic behaviour is simulated. The objectives of the session \Modelling the micro-physics underlying earthquake nucleation processes and rupture" were: (1) to explore properties that can be modelled at the grain scale, (2) to explore macroscopic behaviour that can be reproduced by such models and (3) to gain insight from micro/meso-scopic changes to predict macroscopic failure. Plenary Plenary papers: David Place, QUAKES, Modelling rock grain interactions at a meso-scale to study the micro and macro-physics of rocks: simplicity vs. complexity. Modelling rock grain interactions: questions Diierent properties such as elasticity, roughness induced friction, thermal eeects and phase transitions can be modelled at a grain scale. However, emergent properties of a model can be used to specify the material properties. For instance rather than specifying a roughness at the grain scale, an assemblage of smaller grains can be used. What are the properties that need to be modelled at the grain scale? What properties can be simulated without excessive computational cost? What is the impact in the macroscopic behaviour of not modelling a given property? 77