金曜セミナー(4月7日)David Mainprice氏 (Université Montpellier 2)

Length and time scales in mineral and rock physics – what relationship to seismology ?

In this talk I will review various methods, and experimental results of mineral and rock physics and their application to the length and time scales relevant to seismology. I will start at the atomic scale and finishing at the planetary scale. The impact of atomic scale modelling has allowed Earth scientist to have estimates of elastic constants at extreme pressures and temperatures that are not yet accessible with experiments. However, experimentalists are advancing to higher temperatures and pressure every year ! Atomic scale modelling has also been applied to crystal defects, such as point defects and dislocations with applications to rheology, crystal preferred orientation and seismic anisotropy. The development of effective media methods in elasticity and plasticity allows the integration of single crystal properties to polycrystalline aggregates. Classical methods for elasticity such as the Voigt-Reuss-Hill averages are appropriate when there are no cracks, pores or fluids present. Other techniques such as the Self-Consistent (SC) and Differential Effective Media (DEM) can be applied to more complex micro-structures. Several more recent methods, such as the Backus, Schoenberg and Muir, Asymptotic Expansion Homogenization (AEH), Dynamic Wave Propagation (DWP) target layered media, but have not been extensively tested using experimental data.